diff options
Diffstat (limited to 'project/templates/steelman.xhtml')
| -rw-r--r-- | project/templates/steelman.xhtml | 2437 |
1 files changed, 2437 insertions, 0 deletions
diff --git a/project/templates/steelman.xhtml b/project/templates/steelman.xhtml new file mode 100644 index 0000000..11136cf --- /dev/null +++ b/project/templates/steelman.xhtml @@ -0,0 +1,2437 @@ + +{%- extends "base.xhtml" -%} + + + +{%- block title -%}D, Parasail, Pascal and Rust vs The Steelman{%- endblock -%} + + + +{%- block style %} + <link href="/css/steelman.css" rel="stylesheet" /> +{% endblock -%} + + + +{%- block content %} +<h4>D, Parasail, Pascal, and Rust vs The Steelman</h4> + +<h5>29/10/2017</h5> + + +<h5>Overview</h5> + +<p>From 1975 to 1978 the United States Department of Defense sought to establish a set of +requirements for a single high level programming language that would also be appropriate for use in +Defense embedded systems. After successively more refined versions of the requirements from Strawman +through to Ironman, this effort culminated in Steelman. The Ada programming language, possibly the +gold standard language for writing safe and secure software, was designed to comply with Steelman. +</p> + +<p>In 1996 David A. Wheeler <a href="http://www.adahome.com/History/Steelman/steeltab.htm" +class="external">wrote a paper</a> that compared Ada, C, C++, and Java against the Steelman. This +served to highlight the strengths and weaknesses of those languages, areas that could be improved, +and a scant few requirement points that perhaps aren't even applicable anymore. Since then several +more programming languages capable of systems work have been created, so it's time for an update. +More datapoints! Hence, this article will conduct a similar comparison, instead using D, Parasail, +Pascal, and Rust.</p> + + +<h5>The Languages</h5> + +<p><a href="https://dlang.org/" class="external">D</a> was created originally as a reworking of C++ +in 2000-2001. It serves to represent a progression of the C language family, adding features +including contracts, optional garbage collection, and a standard threading model.</p> + +<p><a href="https://forge.open-do.org/plugins/moinmoin/parasail/" class="external">Parasail</a> is a +research language created in 2009 by AdaCore, the main vendor of Ada compiler tooling today. The +language is designed with implicit parallelism throughout, <a href="https://www.embedded.com/design/programming-languages-and-tools/4375616/1/ParaSail--Less-is-more-with-multicore" +class="external">simplifying and adding static checking</a> to eliminate as many sources of errors +as possible. It represents a possible future direction for Ada derived languages.</p> + +<p><a href="https://en.wikipedia.org/wiki/Pascal_(programming_language)" class="external">Pascal +</a>, like C, predates the Steelman requirements and so they cannot have had any influence at all on +the language. It was designed for formal specification and +<a href="https://www.tutorialspoint.com/pascal/pascal_overview.htm" class="external">teaching +algorithms</a>. Later dialects were used to develop several high profile software projects, +including Skype, Photoshop, and the original Mac OS. It is useful to consider as a precusor of Ada, +sharing many points of functionality and style.</p> + +<p><a href="https://www.rust-lang.org/" class="external">Rust</a> is the newest language here, +created in 2010. It is an odd mix of C and ML influence, placing more emphasis on the functional +paradigm than other systems languages. Its main claim to fame is adding another method of heap +memory safety via <a href="https://en.wikipedia.org/wiki/Substructural_type_system" +class="external">affine typing</a>.</p> + +<table id="lang"> + <tr> + <td> + <div class="figure"> + <img src="/img/logo_d_small.png" + alt="Logo for the D programming language" + height="124" + width="164" /> + <div class="figcaption">D</div> + </div> + </td> + <td> + <div class="figure"> + <img src="/img/logo_parasail_small.png" + alt="Logo for the Parasail programming language" + height="144" + width="149" /> + <div class="figcaption">Parasail</div> + </div> + </td> + </tr> + <tr> + <td> + <div class="figure"> + <img src="/img/logo_pascal_small.png" + alt="A picture of Blaise Pascal to stand in as a logo for the Pascal programming language" + height="144" + width="142" /> + <div class="figcaption">Pascal*</div> + </div> + </td> + <td> + <div class="figure"> + <img src="/img/logo_rust_small.png" + alt="Logo for the Rust programming language" + height="144" + width="144" /> + <div class="figcaption">Rust</div> + </div> + </td> + </tr> +</table> + +<p>* Pascal does not have an official logo, so a picture of +<a href="https://en.wikipedia.org/wiki/Blaise_Pascal" class="external">Blaise Pascal</a>, in whose +honour the language is named, will have to do.</p> + + +<h5>Rules for Comparison</h5> + +<p>The rule used for this article is that a language provides a feature if:</p> +<ol> + <li>that feature is defined in the documents widely regarded as the language's defining + document(s), <b>or</b></li> + <li>that feature is widely implemented by compilers typically used for that language with + essentially the same semantics.</li> +</ol> + +<p>Note the bolded difference from the rules in Wheeler's paper. This is so later dialects of Pascal +can be considered, rather than strictly adhering to the ISO standard. The other three languages are +unaffected by this change. Aside from that, effort has been made to keep the evaluation as similar +as practical to the previous work.</p> + +<p>The defining documents used for each of these languages are as follows:</p> +<ul> + <li>D: The <a href="https://dlang.org/spec/spec.html" class="external">D Language + Specification</a> and the accompanying <a href="https://dlang.org/phobos/index.html" + class="external">Library Reference</a>.</li> + <li>Parasail: The <a href="https://forge.open-do.org/plugins/moinmoin/parasail/FrontPage?action=AttachFile&do=view&target=parasail_ref_manual.pdf" + class="external">Parasail Reference Manual</a>. Parasail is still a work in progress, and no + efforts to standardise it have yet been started.</li> + <li>Pascal: ISO 7185 details Standard Pascal, and is available at several places in various + formats. The copy used here was retrieved from <a href="http://www.pascal-central.com/standards.html" + class="external">Pascal Central</a>. Checking for features of more recent Pascal dialects is + done on a more ad hoc basis.</li> + <li>Rust: The closest there is to a definition of the language is given in + <a href="https://doc.rust-lang.org/reference/" class="external">The Rust Reference</a>. It + should be noted that this document is not complete, nor stable. Supplementary information was + obtained from <a href="https://rustbyexample.com/" class="external">Rust by Example</a>. No work + to standardise Rust has been started yet either.</li> +</ul> + + +<h5>Results and Conclusions</h5> + +<p>The appendix lists the Steelman requirements and how well each language supports them. The +following table shows a summary:</p> + +<table id="results"> + <tr> + <th>Language</th> + <th>"No"</th> + <th>"Partial"</th> + <th>"Mostly"</th> + <th>"Yes"</th> + <th>Percentage with "Mostly" or "Yes"</th> + </tr> + <tr> + <td>D</td> + <td>7</td> + <td>15</td> + <td>25</td> + <td>66</td> + <td>81%</td> + </tr> + <tr> + <td>Parasail</td> + <td>11</td> + <td>6</td> + <td>11</td> + <td>85</td> + <td>85%</td> + </tr> + <tr> + <td>Pascal</td> + <td>19</td> + <td>16</td> + <td>11</td> + <td>67</td> + <td>69%</td> + </tr> + <tr> + <td>Rust</td> + <td>12</td> + <td>19</td> + <td>23</td> + <td>59</td> + <td>73%</td> + </tr> +</table> + +<p>Note that these raw numbers should not be taken at face value. They are a summary of how well the +overall requirements are met, no more, no less. Attention should be directed towards specific +requirements to determine the strengths and weaknesses of each language and the suitability for a +particular purpose. Furthermore, some features are not covered by Steelman at all, such as support +for functional programming or object oriented programming.</p> + +<p>The following are high level comments on these programming languages and how they relate:</p> +<ul> + <li>All of these languages suffer from either not being standardised or, in the case of Pascal, + having fragmented into multiple non-standard dialects afterwards. This impacts their scores for + requirements 1H, 13A, 13B.</li> + <li>Requirements 2A, 5D, 5E are perhaps not suitable to apply to today's programming languages, + due to the presence of Unicode, functional programming, and use of initial values for safety + guarantees respectively.</li> + <li>Parasail scores very well on the Steelman, as expected from its Ada heritage and Ada having + been explicitly designed to fit these requirements. Most of the "no" and "partial" items for + Parasail are due to the lack of low level interfaces and pragmas (likely due to its experimental + nature) and due to the pervasive implicit parallelism and increased static guarantees.</li> + <li>D does significantly better than C, C++, or Java from the previous comparison due to the + inclusion of new features such as parallelism into the language. Contracts in particular allow + the subtyping requirements 3B, 3C, 3D to be at least partially satisfied. Most of its failures + here can be attributed to its C legacy, including syntax, grammar, number of operator precedence + levels, pointers, primitive type flexibility, and integer overflow handling. Noteworthy is the + lack of a preprocessor.</li> + <li>Pascal, at least the ISO standard variety, does not support parallelism and leaves a lot of + error handling and floating point details up to implementation. Nonetheless its syntax, grammar, + and more expressive type system (aside from the well known string length issue) contribute to + its higher score compared to C.</li> + <li>Rust lacks subtyping or contracts to emulate the requirements 3B, 3D, and its use of return + values instead of exceptions leads to lower scores on 10A through 10G. The syntax is already + notorious and the presence of macros may cause further issues. But it is definitely a + significant improvement on C with an emphasis on immutability from its functional roots. The + central failure of the language is the myopic focus on the affine typing solution to heap + allocation and thread safety. The creators do not seem to realise that other solutions already + exist, and that dynamic memory allocation is not the only safety issue a programmer has to cope + with.</li> + <li>Parasail and Ada remain the only languages so far considered that support fixed point types + in the core language.</li> + <li>Rust has by far the most support for the functional programming paradigm.</li> +</ul> + + +<h5>Appendix: Table Comparing the Languages to Steelman</h5> + +<p>As in Wheeler's paper, this table shows each Steelman requirement on the left and then how well +each of the four languages considered meet that requirement on the right. Some explanatory notes are +included for a few of the requirements.</p> + +<p>Note that due to the standardisation issues each of these languages has, a (fortunately quite +low) number of these turned out to be educated guesses. Fairness was the goal, but nonetheless +reader discretion is advised.</p> + + +<div class="accordian"> + <input type="checkbox" name="collapse" id="handle1" /> + <label for="handle1">Toggle Appendix Table</label> + <div class="hidden_content"> + +<table id="appendix"> + <tr> + <th style="width: 30em">Requirement</th> + <th style="width: 7.5em">D</th> + <th style="width: 7.5em">Parasail</th> + <th style="width: 7.5em">Pascal</th> + <th style="width: 7.5em">Rust</th> + </tr> + + <tr> + <td rowspan="2"> + 1A. Generality. The language shall provide generality only to the extent necessary + to satisfy the needs of embedded computer applications. Such applications involve + real time control, self diagnostics, input-output to nonstandard peripheral devices, + parallel processing, numeric computation, and file processing. + </td> + <td class="yn">yes</td> + <td class="yn">no?</td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + Parasail does not specify ways to directly control hardware, nor any interfaces to other + languages. + </td> + </tr> + + <tr> + <td rowspan="2"> + 1B. Reliability. The language should aid the design and development of reliable + programs. The language shall be designed to avoid error prone features and to + maximize automatic detection of programming errors. The language shall require some + redundant, but not duplicative, specifications in programs. Translators shall produce + explanatory diagnostic and warning messages, but shall not attempt to correct + programming errors. + </td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + <td class="yn">partial?</td> + <td class="yn">mostly?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 1C. Maintainability. The language should promote ease of program maintenance. It + should emphasize program readability (i.e., clarity, understandability, and + modifiability of programs). The language should encourage user documentation of + programs. It shall require explicit specification of programmer decisions and shall + provide defaults only for instances where the default is stated in the language + definition, is always meaningful, reflects the most frequent usage in programs, and may + be explicitly overridden. + </td> + <td class="yn">partial?</td> + <td class="yn">yes?</td> + <td class="yn">mostly?</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + Parasail was designed with readability in mind, although it suffers slightly from having + several different ways to do something. Pascal was designed for teaching structured + programming. D inherits a lot of the syntactical traps of C-family languages. Rust has + exceedingly terse and difficult to read syntax. + </td> + </tr> + + <tr> + <td rowspan="2"> + 1D. Efficiency. The language design should aid the production of efficient object + programs. Constructs that have unexpectedly expensive implementations should be easily + recognizable by translators and by users. Features should be chosen to have a simple and + efficient implementation in many object machines, to avoid execution costs for available + generality where it is not needed, to maximize the number of safe optimizations + available to translators, and to ensure that unused and constant portions of programs + will not add to execution costs. Execution time support packages of the language shall + not be included in object code unless they are called. + </td> + <td class="yn">partial?</td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + D incorporates garbage collection to some extent. Parasail is designed to allow as much + implicit parallelism as possible. + </td> + </tr> + + <tr> + <td rowspan="2"> + 1E. Simplicity. The language should not contain unnecessary complexity. It should have a + consistent semantic structure that minimizes the number of underlying concepts. It + should be as small as possible consistent with the needs of the intended applications. + It should have few special cases and should be composed from features that are + individually simple in their semantics. The language should have uniform syntactic + conventions and should not provide several notations for the same concept. No arbitrary + restriction should be imposed on a language feature. + </td> + <td class="yn">yes?</td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + Parasail allows several syntactical forms that are identical in meaning. + </td> + </tr> + + <tr> + <td rowspan="2"> + 1F. Implementability. The language shall be composed from features that are understood + and can be implemented. The semantics of each feature should be sufficiently well + specified and understandable that it will be possible to predict its interaction with + other features. To the extent that it does not interfere with other requirements, the + language shall facilitate the production of translators that are easy to implement and + are efficient during translation. There shall be no language restrictions that are not + enforceable by translators. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + All of these languages have been reasonably implemented. + </td> + </tr> + + <tr> + <td rowspan="2"> + 1G. Machine Independence. The design of the language should strive for machine + independence. It shall not dictate the characteristics of object machines or operating + systems except to the extent that such characteristics are implied by the semantics of + control structures and built-in operations. It shall attempt to avoid features whose + semantics depend on characteristics of the object machine or of the object machine + operating system. Nevertheless, there shall be a facility for defining those portions of + programs that are dependent on the object machine configuration and for conditionally + compiling programs depending on the actual configuration. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 1H. Complete Definition. The language shall be completely and unambiguously defined. To + the extent that a formal definition assists in achieving the above goals (i.e., all of + section 1), the language shall be formally defined. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">mostly?</td> + <td class="yn">mostly?</td> + </tr> + <tr> + <td colspan="4"> + While Pascal is the only one of these languages with an ISO standard, most Pascal + programming is done with more recent extended dialects. Rust reference material does not + completely describe the language. + </td> + </tr> + + <tr> + <td rowspan="2"> + 2A. Character Set. The full set of character graphics that may be used in source + programs shall be given in the language definition. Every source program shall also have + a representation that uses only the following 55 character subset of the ASCII graphics: + %&'()*+,-./:;<=>? 0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ_ Each additional + graphic (i.e., one in the full set but not in the 55 character set) may be replaced by a + sequence of (one or more) characters from the 55 character set without altering the + semantics of the program. The replacement sequence shall be specified in the language + definition. + </td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 2B. Grammar. The language should have a simple, uniform, and easily parsed grammar and + lexical structure. The language shall have free form syntax and should use familiar + notations where such use does not conflict with other goals. + </td> + <td class="yn">partial?</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + Use of familiar notations is something that Parasail arguably takes too far, see 1E. D + inherits some grammar issues from C/C++. Rust has less borrowing from that source but is + still very ad hoc. + </td> + </tr> + + <tr> + <td rowspan="2"> + 2C. Syntactic Extensions. The user shall not be able to modify the source language + syntax. In particular the user shall not be able to introduce new precedence rules or to + define new syntactic forms. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + Rust has macros, which can be used to add new syntax to the language. + </td> + </tr> + + <tr> + <td rowspan="2"> + 2D. Other Syntactic Issues. Multiple occurrences of a language defined symbol appearing + in the same context shall not have essentially different meanings. Lexical units (i.e., + identifiers, reserved words, single and multicharacter symbols, numeric and string + literals, and comments) may not cross line boundaries of a source program. All key word + forms that contain declarations or statements shall be bracketed (i.e., shall have a + closing as well as an opening key word). Programs may not contain unmatched brackets of + any kind. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D, Pascal, and Rust permit multi line comments. D and Rust use opening and closing + braces rather than key words. + </td> + </tr> + + <tr> + <td rowspan="2"> + 2E. Mnemonic Identifiers. Mnemonically significant identifiers shall be allowed. There + shall be a break character for use within identifiers. The language and its translators + shall not permit identifiers or reserved words to be abbreviated. (Note that this does + not preclude reserved words that are abbreviations of natural language words.) + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 2F. Reserved Words. The only reserved words shall be those that introduce special + syntactic forms (such as control structures and declarations) or that are otherwise used + as delimiters. Words that may be replaced by identifiers, shall not be reserved (e.g., + names of functions, types, constants, and variables shall not be reserved). All reserved + words shall be listed in the language definition. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 2G. Numeric Literals. There shall be built-in decimal literals. There shall be no + implicit truncation or rounding of integer and fixed point literals. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">mostly?</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + Parasail Univ_Integer and Univ_Real types provide arbitrary precision. Rust provides + configurable ways to treat integer overflow, with the default release mode being + wrapping by two's complement. D allows implicit wrapping of integers. Pascal real types + are implementation defined. Only Parasail supports fixed point types. + </td> + </tr> + + <tr> + <td rowspan="2"> + 2H. String Literals. There shall be a built-in facility for fixed length string + literals. String literals shall be interpreted as one-dimensional character arrays. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + Univ_Strings in Parasail are vectors of Univ_Character, not arrays. + </td> + </tr> + + <tr> + <td rowspan="2"> + 2I. Comments. The language shall permit comments that are introduced by a special (one + or two character) symbol and terminated by the next line boundary of the source program. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + Line comments were introduced in Turbo Pascal, but are not part of the ISO standard. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3A. Strong Typing. The language shall be strongly typed. The type of each variable, + array and record component, expression, function, and parameter shall be determinable + during translation. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + Some implicit conversion is allowed in D, such as booleans to integral types, one way + conversion from enums to integers, and some automatic promotion of integer types. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3B. Type Conversions. The language shall distinguish the concepts of type (specifying + data elements with common properties, including operations), subtype (i.e., a subset of + the elements of a type, that is characterized by further constraints), and + representations (i.e., implementation characteristics). There shall be no implicit + conversions between types. Explicit conversion operations shall be automatically defined + between types that are characterized by the same logical properties. + </td> + <td class="yn">partial?</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + D, Rust do not have subtypes, although class structures in D can be used with contract + programming to provide the same functionality. D allows implicit promotion of integer + types. D, Rust have primitive types that are tightly coupled to the typical + implementation characteristics of computer hardware. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3C. Type Definitions. It shall be possible to define new data types in programs. A type + may be defined as an enumeration, an array or record type, an indirect type, an existing + type, or a subtype of an existing type. It shall be possible to process type definitions + entirely during translation. An identifier may be associated with each type. No + restriction shall be imposed on user defined types unless it is imposed on all types. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D, Rust do not have subtypes. D however can emulate similar functionality with type + invariant contracts for user defined classes. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3D. Subtype Constraints. The constraints that characterize subtypes shall include range, + precision, scale, index ranges, and user defined constraints. The value of a subtype + constraint for a variable may be specified when the variable is declared. The language + should encourage such specifications. [Note that such specifications can aid the + clarity, efficiency, maintainability, and provability of programs.] + </td> + <td class="yn">partial</td> + <td class="yn">yes?</td> + <td class="yn">mostly?</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + D does not have subtypes but has similar functionality with class type invariants. Rust + doesn't have subtypes at all. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1A. Numeric Values. The language shall provide distinct numeric types for exact and + for approximate computation. Numeric operations and assignment that would cause the most + significant digits of numeric values to be truncated (e.g., when overflow occurs) shall + constitute an exception situation. + </td> + <td class="yn">partial?</td> + <td class="yn">yes</td> + <td class="yn">partial?</td> + <td class="yn">mostly?</td> + </tr> + <tr> + <td colspan="4"> + Numeric overflow does not cause an exception in D, but the language provides standard + ways to check for the situation. Overflow error handling in Pascal is implementation + defined. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1B. Numeric Operations. There shall be built-in operations (i.e., functions) for + conversion between the numeric types. There shall be operations for addition, + subtraction, multiplication, division, negation, absolute value, and exponentiation to + integer powers for each numeric type. There shall be built-in equality (i.e., equal and + unequal) and ordering operations (i.e., less than, greater than, less than or equal, and + greater than or equal) between elements of each numeric type. Numeric values shall be + equal if and only if they have exactly the same abstract value. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D uses a library abs() function instead of a built-in operator. Pascal does not have + built-in operators for absolute value or exponentiation. Rust uses library abs() and + pow() functions instead of built-in absolute value and exponentiation operators. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1C. Numeric Variables. The range of each numeric variable must be specified in + programs and shall be determined by the time of its allocation. Such specifications + shall be interpreted as the minimum range to be implemented and as the maximum range + needed by the application. Explicit conversion operations shall not be required between + numeric ranges. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + Counting built-in integer types as specifying a range, all these languages do so to some + extent. Parasail is the only one that supports user defined custom ranges. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1D. Precision. The precision (of the mantissa) of each expression result and variable + in approximate computations must be specified in programs, and shall be determinable + during translation. Precision specifications shall be required for each such variable. + Such specifications shall be interpreted as the minimum accuracy (not significance) to + be implemented. Approximate results shall be implicitly rounded to the implemented + precision. Explicit conversions shall not be required between precisions. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">no</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D defines specific precisions for double and float, along with a minimum precision for + real. Custom precisions can be defined for storage only, but all operations happen on + doubles/floats/reals. In Standard Pascal precision of real number types is entirely + implementation defined. Rust defines specific precisions for 32 and 64 bit floats, but + no other control over precision. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1E. Approximate Arithmetic Implementation. Approximate arithmetic will be implemented + using the actual precisions, radix, and exponent range available in the object machine. + There shall be built-in operations to access the actual precision, radix, and exponent + range of the implementation. + </td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">partial</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + In Standard Pascal the values taken by real number types are entirely implementation + defined. In practice, this usually means implementation using the actual precisions + available in the object machine. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1F. Integer and Fixed Point Numbers. Integer and fixed point numbers shall be treated + as exact numeric values. There shall be no implicit truncation or rounding in integer + and fixed point computations. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D, Pascal, Rust don't support fixed point numbers, and permit implicit wrapping with + integer calculations. Dealing with overflow, wrapping, and other error conditions in + Pascal is implementation defined. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1G. Fixed Point Scale. The scale or step size (i.e., the minimal representable + difference between values) of each fixed point variable must be specified in programs + and be determinable during translation. Scales shall not be restricted to powers of two. + </td> + <td class="yn">no</td> + <td class="yn">yes</td> + <td class="yn">no</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + Of these four languages, only Parasail supports fixed point types. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-1H. Integer and Fixed Point Operations. There shall be integer and fixed point + operations for modulo and integer division and for conversion between values with + different scales. All built-in and predefined operations for exact arithmetic shall + apply between arbitrary scales. Additional operations between arbitrary scales shall be + definable within programs. + </td> + <td class="yn">no</td> + <td class="yn">yes</td> + <td class="yn">no</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + All support "modulo" operators; D, Pascal, Rust don't support fixed point numbers. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-2A. Enumeration Type Definitions. There shall be types that are definable in programs + by enumeration of their elements. The elements of an enumeration type may be identifiers + or character literals. Each variable of an enumeration type may be restricted to a + contiguous subsequence of the enumeration. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D does not permit character literals in an enumeration, nor restriction to a + subsequence. Rust enums are more flexible in content, but still don't support + restriction to a subsequence. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-2B. Operations on Enumeration Types. Equality, inequality, and the ordering operations + shall be automatically defined between elements of each enumeration type. Sufficient + additional operations shall be automatically defined so that the successor, predecessor, + the position of any element, and the first and last element of the type may be computed. + </td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + <td class="yn">mostly?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-2C. Boolean Type. There shall be a predefined type for Boolean values. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D's boolean type is weakly typed. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-2D. Character Types. Character sets shall be definable as enumeration types. Character + types may contain both printable and control characters. The ASCII character set shall + be predefined. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3A. Composite Type Definitions. It shall be possible to define types that are + Cartesian products of other types. Composite types shall include arrays (i.e., composite + data with indexable components of homogeneous types) and records (i.e., composite data + with labeled components of heterogeneous type). + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + All have arrays and records. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3B. Component Specifications. For elements of composite types, the type of each + component (i.e., field) must be explicitly specified in programs and determinable during + translation. Components may be of any type (including array and record types). Range, + precision, and scale specifications shall be required for each component of appropriate + numeric type. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + Range, precision, and scale specifications are included in numeric type definitions + (with support varying, see 3-1). + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3C. Operations on Composite Types. A value accessing operation shall be automatically + defined for each component of composite data elements. Assignment shall be automatically + defined for components that have alterable values. A constructor operation (i.e., an + operation that constructs an element of a type from its constituent parts) shall be + automatically defined for each composite type. An assignable component may be used + anywhere in a program that a variable of the component's type is permitted. There shall + be no automatically defined equivalence operations between values of elements of a + composite type. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3D. Array Specifications. Arrays that differ in number of dimensions or in component + type shall be of different types. The range of subscript values for each dimension must + be specified in programs and may be determinable at the time of array allocation. The + range of each subscript value must be restricted to a contiguous sequence of integers or + to a contiguous sequence from an enumeration type. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D and Rust array indexes can only start at zero and cannot use enumerations. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3E. Operations on Subarrays. There shall be built-in operations for value access, + assignment, and catenation of contiguous sections of one-dimensional arrays of the same + component type. The results of such access and catenation operations may be used as + actual input parameter. + </td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">no</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + Pascal has extremely limited array slicing and does not have a built-in array + concatenation operator. Rust has array slicing facilities, but lacks a built-in array + concatenation operator. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3F. Nonassignable Record Components. It shall be possible to declare constants and + (unary) functions that may be thought of as record components and may be referenced + using the same notation as for accessing record components. Assignment shall not be + permitted to such components. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">no?</td> + <td class="yn">no?</td> + </tr> + <tr> + <td colspan="4"> + D classes can include constants and functions. Parasail type inferfaces can include + constants and functions. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3G. Variants. It shall be possible to define types with alternative record structures + (i.e., variants). The structure of each variant shall be determinable during + translation. + </td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D classes can be used to simulate runtime variants. D also has untagged unions. Pascal + has variant records. Rust has tagged unions called "sum types". + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3H. Tag Fields. Each variant must have a nonassignable tag field (i.e., a component + that can be used to discriminate among the variants during execution). It shall not be + possible to alter a tag field without replacing the entire variant. + </td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3I. Indirect Types. It shall be possible to define types whose elements are indirectly + accessed. Elements of such types may have components of their own type, may have + substructure that can be altered during execution, and may be distinct while having + identical component values. Such types shall be distinguishable from other composite + types in their definitions. An element of an indirect type shall remain allocated as + long as it can be referenced by the program. [Note that indirect types require pointers + and sometimes heap storage in their implementation.] + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-3J. Operations on Indirect Types. Each execution of the constructor operation for an + indirect type shall create a distinct element of the type. An operation that + distinguishes between different elements, an operation that replaces all of the + component values of an element without altering the element's identity, and an operation + that produces a new element having the same component values as its argument, shall be + automatically defined for each indirect type. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-4A. Bit Strings (i.e., Set Types). It shall be possible to define types whose elements + are one-dimensional Boolean arrays represented in maximally packed form (i.e, whose + elements are sets). + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + D provides bit arrays in the standard library in std.bitmanip. It is easy enough to + construct bit strings in Rust using structs or integer types, but the language itself + does not provide them as built in functionality. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-4B. Bit String Operations. Set construction, membership (i.e., subscription), set + equivalence and nonequivalence, and also complement, intersection, union, and symmetric + difference (i.e., component-by-component negation, conjunction, inclusive disjunction, + and exclusive disjunction respectively) operations shall be defined automatically for + each set type. + </td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-5A. Encapsulated Definitions. It shall be possible to encapsulate definitions. An + encapsulation may contain declarations of anything (including the data elements and + operations comprising a type) that is definable in programs. The language shall permit + multiple explicit instantiations of an encapsulation. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + All of these languages have modules as their unit of encapsulation. + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-5B. Effect of Encapsulation. An encapsulation may be used to inhibit external access + to implementation properties of the definition. In particular, it shall be possible to + prevent external reference to any declaration within the encapsulation including + automatically defined operations such as type conversions and equality. Definitions that + are made within an encapsulation and are externally accessible may be renamed before use + outside the encapsulation. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 3-5C. Own Variables. Variables declared within an encapsulation, but not within a + function, procedure, or process of the encapsulation, shall remain allocated and retain + their values throughout the scope in which the encapsulation is instantiated. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 4A. Form of Expressions. The parsing of correct expressions shall not depend on the + types of their operands or on whether the types of the operands are built into the + language. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 4B. Type of Expressions. It shall be possible to specify the type of any expression + explicitly. The use of such specifications shall be required only where the type of the + expression cannot be uniquely determined during translation from the context of its use + (as might be the case with a literal). + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 4C. Side Effects. The language shall attempt to minimize side effects in expressions, + but shall not prohibit all side effects. A side effect shall not be allowed if it would + alter the value of a variable that can be accessed at the point of the expression. Side + effects shall be limited to own variables of encapsulations. The language shall permit + side effects that are necessary to instrument functions and to do storage management + within functions. The order of side effects within an expression shall not be + guaranteed. [Note that the latter implies that any program that depends on the order of + side effects is erroneous.] + </td> + <td class="yn">mostly?</td> + <td class="yn">yes?</td> + <td class="yn">mostly?</td> + <td class="yn">mostly?</td> + </tr> + <tr> + <td colspan="4"> + Parasail does not permit global variables. + </td> + </tr> + + <tr> + <td rowspan="2"> + 4D. Allowed Usage. Expressions of a given type shall be allowed wherever both constants + and variables of the type are allowed. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 4E. Translation Time Expressions. Expressions that can be evaluated during translation + shall be permitted wherever literals of the type are permitted. Translation time + expressions that include only literals and the use of translation time facilities (see + 11C) shall be evaluated during translation. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 4F. Operator Precedence Levels. The precedence levels (i.e., binding strengths) of all + (prefix and infix) operators shall be specified in the language definition, shall not be + alterable by the user, shall be few in number, and shall not depend on the types of the + operands. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + Pascal has 5 levels, Parasail has 7, Rust has 13 and D has 15-19 depending on how you + count them. For comparison, Ada has 6. + </td> + </tr> + + <tr> + <td rowspan="2"> + 4G. Effect of Parentheses. If present, explicit parentheses shall dictate the + association of operands with operators. The language shall specify where explicit + parentheses are required and shall attempt to minimize the psychological ambiguity in + expressions. [Note that this might be accomplished by requiring explicit parentheses to + resolve the operator-operand association whenever a nonassociative operator appears to + the left of an operator of the same precedence at the least-binding precedence level of + any subexpression.] + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 5A. Declarations of Constants. It shall be possible to declare constants of any type. + Such constants shall include both those whose values-are determined during translation + and those whose value cannot be determined until allocation. Programs may not assign to + constants. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 5B. Declarations of Variables. Each variable must be declared explicitly. Variables may + be of any type. The type of each variable must be specified as part of its declaration + and must be determinable during translation. [Note, "variable" throughout this document + refers not only to simple variables but also to composite variables and to components of + arrays and records.] + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + D permits "void *" as a type, which is really a pointer to an unknown type and subverts + the type system. Rust does not require the type of each variable to be explicitly + specified and will infer types instead. + </td> + </tr> + + <tr> + <td rowspan="2"> + 5C. Scope of Declarations. Everything (including operators) declared in a program shall + have a scope (i.e., a portion of the program in which it can be referenced). Scopes + shall be determinable during translation. Scopes may be nested (i.e., lexically + embedded). A declaration may be made in any scope. Anything other than a variable shall + be accessable within any nested scope of its definition. + </td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 5D. Restrictions on Values. Procedures, functions, types, labels, exception situations, + and statements shall not be assignable to variables, be computable as values of + expressions, or be usable as nongeneric parameters to procedures or functions. + </td> + <td class="yn">no</td> + <td class="yn">no</td> + <td class="yn">no?</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + D and Pascal allow pointers to functions. Parasail allows lambda expressions. Rust has + first class functions. + </td> + </tr> + + <tr> + <td rowspan="2"> + 5E. Initial Values. There shall be no default initial-values for variables. + </td> + <td class="yn">partial</td> + <td class="yn">partial</td> + <td class="yn">partial?</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + D defines initial values for all types. Parasail sets initial values of all 'optional' + types to null. Rust does not assign default initial values, but instead requires the + programmer to always provide an initial value. All of these instances are done to + support reliability. + </td> + </tr> + + <tr> + <td rowspan="2"> + 5F. Operations on Variables. Assignment and an implicit value access operation shall be + automatically defined for each variable. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 5G. Scope of Variables. The language shall distinguish between open scopes (i.e., those + that are automatically included in the scope of more globally declared variables) and + closed scopes (i.e., those in which nonlocal variables must be explicitly Imported). + Bodies of functions, procedures, and processes shall be closed scopes. Bodies of + classical control structures shall be open scopes. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 6A. Basic Control Facility. The (built-in) control mechanisms should be of minimal + number and complexity. Each shall provide a single capability and shall have a + distinguishing syntax. Nesting of control structures shall be allowed. There shall be no + control definition facility. Local scopes shall be allowed within the bodies of control + statements. Control structures shall have only one entry point and shall exit to a + single point unless exited via an explicit transfer of control (where permitted, see + 6G), or the raising of an exception (see 10C). + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 6B. Sequential Control. There shall be a control mechanism for sequencing statements. + The language shall not impose arbitrary restrictions on programming style, such as the + choice between statement terminators and statement separators, unless the restriction + makes programming errors less likely. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D and Rust use statement terminators. Pascal and Parasail use statement separators. + </td> + </tr> + + <tr> + <td rowspan="2"> + 6C. Conditional Control. There shall be conditional control structures that permit + selection among alternative control paths. The selected path may depend on the value of + a Boolean expression, on a computed choice among labeled alternatives, or on the true + condition in a set of conditions. The language shall define the control action for all + values of the discriminating condition that are not specified by the program. The user + may supply a single control path to be used when no other path is selected. Only the + selected branch shall be compiled when the discriminating condition is a translation + time expression. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 6D. Short Circuit Evaluation. There shall be infix control operations for short circuit + conjunction and disjunction of the controlling Boolean expression in conditional and + iterative control structures. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + Standard Pascal does not provide infix control operations, but both Extended Pascal and + Turbo Pascal do. + </td> + </tr> + + <tr> + <td rowspan="2"> + 6E. Iterative Control. There shall be an iterative control structure. The iterative + control may be exited (without reentry) at an unrestricted number of places. A + succession of values from an enumeration type or the integers may be associated with + successive iterations and the value for the current iteration accessed as a constant + throughout the loop body. + </td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + In D, the loop control variable is not considered a constant. + </td> + </tr> + + <tr> + <td rowspan="2"> + 6G. Explicit Control Transfer. There shall be a mechanism for control transfer (i.e., + the go to). It shall not be possible to transfer out of closed scopes, into narrower + scopes, or into control structures. It shall be possible to transfer out of classical + control structures. There shall be no control transfer mechanisms in the form of + switches, designational expressions, label variables, label parameters, or alter + statements. + </td> + <td class="yn">yes?</td> + <td class="yn">partial</td> + <td class="yn">yes</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + Neither Parasail nor Rust support goto. However both support break/continue statements + that serve the same purpose in many cases. + </td> + </tr> + + <tr> + <td rowspan="2"> + 7A. Function and Procedure Definitions. Functions (which return values to expressions) + and procedures (which can be called as statements) shall be definable in programs. + Functions or procedures that differ in the number or types of their parameters may be + denoted by the same identifier or operator (i.e., overloading shall be permitted). [Note + that redefinition, as opposed to overloading, of an existing function or procedure is + often error prone.] + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + Rust does not support ad-hoc polymorphism. It must be emulated using the trait system. + </td> + </tr> + + <tr> + <td rowspan="2"> + 7B. Recursion. It shall be possible to call functions and procedures recursively. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> +   + </td> + </tr> + + <tr> + <td rowspan="2"> + 7C. Scope Rules. A reference to an identifier that is not declared in the most local + scope shall refer to a program element that is lexically global, rather than to one that + is global through the dynamic calling structure. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 7D. Function Declarations. The type of the result for each function must be specified in + its declaration and shall be determinable during translation. The results of functions + may be of any type. If a result is of a nonindirect array or record type then the number + of its components must be determinable by the time of function call. + </td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + <td class="yn">mostly?</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 7F. Formal Parameter Classes. There shall be three classes of formal data parameters: + (a) input parameters, which act as constants that are initialized to the value of + corresponding actual parameters at the time of call, (b) input-output parameters, which + enable access and assignment to the corresponding actual parameters, either throughout + execution or only upon call and prior to any exit, and (c) output parameters, whose + values are transferred to the corresponding actual parameter only at the time of normal + exit. In the latter two cases the corresponding actual parameter shall be determined at + time of call and must be a variable or an assignable component of a composite type. + </td> + <td class="yn">partial</td> + <td class="yn">yes</td> + <td class="yn">partial?</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + D, Pascal and Rust do not identify in, in-out and out parameters. D, Pascal and Rust can + support in-only parameters. + </td> + </tr> + + <tr> + <td rowspan="2"> + 7G. Parameter Specifications. The type of each formal parameter must be explicitly + specified in programs and shall be determinable during translation. Parameters may be of + any type. The language shall not require user specification of subtype constraints for + formal parameters. If such constraints are permitted they shall be interpreted as + assertions and not as additional overloading. Corresponding formal and actual parameters + must be of the same type. + </td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 7H. Formal Array Parameters. The number of dimensions for formal array parameters must + be specified in programs and shall be determinable during translation. Determination of + the subscript range for formal array parameters may be delayed until invocation and may + vary from call to call. Subscript ranges shall be accessible within function and + procedure bodies without being passed as explicit parameters. + </td> + <td class="yn">no</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + Subscript ranges are not accessible in D or Rust. + </td> + </tr> + + <tr> + <td rowspan="2"> + 7I. Restrictions to Prevent Aliasing. The language shall attempt to prevent aliasing + (i.e., multiple access paths to the same variable or record component) that is not + intended, but shall not prohibit all aliasing. Aliasing shall not be permitted between + output parameters nor between an input-output parameter and a nonlocal variable. + Unintended aliasing shall not be permitted between input-output parameters. A + restriction limiting actual input-output parameters to variables that are nowhere + referenced as nonlocals within a function or routine, is not prohibited. All aliasing of + components of elements of an indirect type shall be considered intentional. + </td> + <td class="yn">no</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 8A. Low Level Input-Output. There shall be a few low level input-output operations that + send and receive control information to and from physical channels and devices. The low + level operations shall be chosen to insure that all user level input-output operations + can be defined within the language. + </td> + <td class="yn">partial?</td> + <td class="yn">no?</td> + <td class="yn">partial?</td> + <td class="yn">no?</td> + </tr> + <tr> + <td colspan="4"> + D and some Pascal dialects permit access to memory mapped locations. + </td> + </tr> + + <tr> + <td rowspan="2"> + 8B. User Level Input-Output. The language shall specify (i.e., give calling format and + general semantics) a recommended set of user level input-output operations. These shall + include operations to create, delete, open, close, read, write, position, and + interrogate both sequential and random access files and to alter the association between + logical files and physical devices. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 8C. Input Restrictions. User level input shall be restricted to data whose record + representations are known to the translator (i.e., data that is created and written + entirely within the program or data whose representation is explicitly specified in the + program). + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 8D. Operating System Independence. The language shall not require the presence of an + operating system. [Note that on many machines it will be necessary to provide run-time + procedures to implement some features of the language.] + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 8E. Resource Control. There shall be a few low level operations to interrogate and + control physical resources (e.g., memory or processors) that are managed (e.g., + allocated or scheduled) by built-in features of the language. + </td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + <td class="yn">partial</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + D supports custom garbage collection and thread priorities. Standard Pascal does not + define ways to control physical resources, but popular implementations such as Free + Pascal provide both custom memory management and thread facilities. + </td> + </tr> + + <tr> + <td rowspan="2"> + 8F. Formating. There shall be predefined operations to convert between the symbolic and + internal representation of all types that have literal forms in the language (e.g., + strings of digits to integers, or an enumeration element to its symbolic form). These + conversion operations shall have the same semantics as those specified for literals in + programs. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + In Rust, operations to convert between enumerations and strings are not predefined. + </td> + </tr> + + <tr> + <td rowspan="2"> + 9A. Parallel Processing. It shall be possible to define parallel processes. Processes + (i.e., activation instances of such a definition) may be initiated at any point within + the scope of the definition. Each process (activation) must have a name. It shall not be + possible to exit the scope of a process name unless the process is terminated (or + uninitiated). + </td> + <td class="yn">yes</td> + <td class="yn">mostly</td> + <td class="yn">no</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D provides this functionality with the std.parallelism and core.thread libraries. Rust + provides this with the std::thread library. Parasail is designed to be implicitly + parallel by default, and thus the lightweight threads used do not have names. Pascal + does not have built in thread or process facilities, and must rely on operating system + specific libraries. + </td> + </tr> + + <tr> + <td rowspan="2"> + 9B. Parallel Process Implementation. The parallel processing facility shall be designed + to minimize execution time and space. Processes shall have consistent semantics whether + implemented on multicomputers, multiprocessors, or with interleaved execution on a + single processor. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">no</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 9C. Shared Variables and Mutual Exclusion. It shall be.possible to mark variables that + are shared among parallel processes. An unmarked variable that is assigned on one path + and used on another shall cause a warning. It shall be possible efficiently to perform + mutual exclusion in programs. The language shall not require any use of mutual + exclusion. + </td> + <td class="yn">partial?</td> + <td class="yn">yes</td> + <td class="yn">no</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D supports shared variables and atomic operations, however the idiomatic way of + threading is to rely on immutable data and message passing. + </td> + </tr> + + <tr> + <td rowspan="2"> + 9D. Scheduling. The semantics of the built-in scheduling algorithm shall be + first-in-first-out within priorities. A process may alter its own priority. If the + language provides a default priority for new processes it shall be the priority of its + initiating process. The built-in scheduling algorithm shall not require that + simultaneously executed processes on different processors have the same priority. [Note + that this rule gives maximum scheduling control to the user without loss of efficiency. + Note also that priority specification does not impose a specific execution order among + parallel paths and thus does not provide a means for mutual exclusion.] + </td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + <td class="yn">no</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 9E. Real Time. It shall be possible to access a real time clock. There shall be + translation time constants to convert between the implementation units and the program + units for real time. On any control path, it shall be possible to delay until at least a + specified time before continuing execution. A process may have an accessible clock + giving the cumulative processing time (i.e., CPU time) for that process. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + D provides this in core.time. Parasail provides this in its standard library. + </td> + </tr> + + <tr> + <td rowspan="2"> + 9G. Asynchronous Termination. It shall be possible to terminate another process. The + terminated process may designate the sequence of statements it will execute in response + to the induced termination. + </td> + <td class="yn">yes</td> + <td class="yn">no?</td> + <td class="yn">no</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D achieves this with std.parallelism and std.process. Pascal programs call an operating + system dependent library to perform this. Parasail is structured around implicit + pervasive parallelism so it's questionable how applicable this requirement is. Rust + achieves this with std::process::Child. + </td> + </tr> + + <tr> + <td rowspan="2"> + 9H. Passing Data. It shall be possible to pass data between processes that do not share + variables. It shall be possible to delay such data transfers until both the sending and + receiving processes have requested the transfer. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">no</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D synchronized calls allow this. Rust achieves this with std::sync::mpsc. + </td> + </tr> + + <tr> + <td rowspan="2"> + 9I. Signalling. It shall be possible to set a signal (without waiting), and to wait for + a signal (without delay, if it is already set). Setting a signal, that is not already + set, shall cause exactly one waiting path to continue. + </td> + <td class="yn">mostly?</td> + <td class="yn">mostly?</td> + <td class="yn">no</td> + <td class="yn">mostly?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 9J. Waiting. It shall be possible to wait for, determine, and act upon the first + completed of several wait operations (including those used for data passing, signalling, + and real time). + </td> + <td class="yn">mostly?</td> + <td class="yn">mostly?</td> + <td class="yn">no</td> + <td class="yn">mostly?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 10A. Exception Handling Facility. There shall be an exception handling mechanism for + responding to unplanned error situations detected in declarations and statements during + execution. The exception situations shall include errors detected by hardware, software + errors detected during execution, error situations in built-in operations, and user + defined exceptions. Exception identifiers shall have a scope. Exceptions should add to + the execution time of programs only if they are raised. + </td> + <td class="yn">yes</td> + <td class="yn">partial?</td> + <td class="yn">partial?</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + Standard Pascal does not specify how to treat errors, whether with exceptions or + otherwise. However later variations including FreePascal and Delphi support exceptions. + Parasail attempts to check for all possible errors at compile time, however it is + unclear from the reference manual how hardware problems are handled. Rust opts for using + return value types to show errors rather than exceptions. + </td> + </tr> + + <tr> + <td rowspan="2"> + 10B. Error Situations. The errors detectable during execution shall include exceeding + the specified range of an array subscript, exceeding the specified range of a variable, + exceeding the implemented range of a variable, attempting to access an uninitialized + variable, attempting to access a field of a variant that is not present, requesting a + resource (such as stack or heap storage) when an insufficient quantity remains, and + failing to satisfy a program specified assertion. [Note that some are very expensive to + detect unless aided by special hardware, and consequently their detection will often be + suppressed (see 10G).] + </td> + <td class="yn">partial?</td> + <td class="yn">mostly</td> + <td class="yn">partial</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + Parasail is constructed to detect all of these mentioned errors, except the out of + memory error, at compile time. + </td> + </tr> + + <tr> + <td rowspan="2"> + 10C. Raising Exceptions. There shall be an operation that raises an exception. Raising + an exception shall cause transfer of control to the most local enclosing exception + handler for that exception without completing execution of the current statement or + declaration, but shall not of itself cause transfer out of a function, procedure, or + process. Exceptions that are not handled within a function or procedure shall be raised + again at the point of call in their callers. Exceptions that are not handled within a + process shall terminate the process. Exceptions that can be raised by built-in + operations shall be given in the language definition. + </td> + <td class="yn">yes</td> + <td class="yn">partial</td> + <td class="yn">partial</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + Standard Pascal does not specify how to handle errors, whether exceptions or otherwise, + see 10A. It is unclear from the Parasail reference manual whether actual exceptions are + used in the language, but similar functionality is achieved with compile time + annotations. Rust opts for using return value types to show errors rather than + exceptions. Various functions and macros are provided that more or less covers the same + thing, but not in a way that satisfies this requirement. + </td> + </tr> + + <tr> + <td rowspan="2"> + 10D. Exception Handling. There shall be a control structure for discriminating among the + exceptions that can occur in a specified statement sequence. The user may supply a + single control path for all exceptions not otherwise mentioned in such a discrimination. + It shall be possible to raise the exception that selected the current handler when + exiting the handler. + </td> + <td class="yn">yes</td> + <td class="yn">no?</td> + <td class="yn">partial</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + Standard Pascal does not specify how to handle errors, whether exceptions or otherwise, + see 10A. + </td> + </tr> + + <tr> + <td rowspan="2"> + 10E. Order of Exceptions. The order in which exceptions in different parts of an + expression are detected shall not be guaranteed by the language or by the translator. + </td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 10F. Assertions. It shall be possible to include assertions in programs. If an assertion + is false when encountered during execution, it shall raise an exception. It shall also + be possible to include assertions, such as the expected frequency for selection of a + conditional path, that cannot be verified. [Note that assertions can be used to aid + optimization and maintenance.] + </td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + <td class="yn">no</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + None? of these languages permit assertions of frequency. + </td> + </tr> + + <tr> + <td rowspan="2"> + 10G. Suppressing Exceptions. It shall be possible during translation to suppress + individually the execution time detection of exceptions within a given scope. The + language shall not guarantee the integrity of the values produced when a suppressed + exception occurs. [Note that suppression of an exception is not an assertion that the + corresponding error will not occur.] + </td> + <td class="yn">partial</td> + <td class="yn">no</td> + <td class="yn">no</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + It is possible to statically disallow code from throwing exceptions in D, but that + doesn't fulfil the same function as this requirement. + </td> + </tr> + + <tr> + <td rowspan="2"> + 11A. Data Representation. The language shall permit but not require programs to specify + a single physical representation for the elements of a type. These specifications shall + be separate from the logical descriptions. Physical representation shall include object + representation of enumeration elements, order of fields, width of fields, presence of + "don't care" fields, positions of word boundaries, and object machine addresses. In + particular, the facility shall be sufficient to specify the physical representation of + any record whose format is determined by considerations that are entirely external to + the program, translator, and language. The language and its translators shall not + guarantee any particular choice for those aspects of physical representation that are + unspecified by the program. It shall be possible to specify the association of physical + resources (e.g., interrupts) to program elements (e.g., exceptions or signals). + </td> + <td class="yn">partial?</td> + <td class="yn">no?</td> + <td class="yn">no</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 11C. Translation Time Facilities. To aid conditional compilation, it shall be possible + to interrogate properties that are known during translation including characteristics of + the object configuration, of function and procedure calling environments, and of actual + parameters. For example, it shall be possible to determine whether the caller has + suppressed a given exception, the callers optimization criteria, whether an actual + parameter is a translation time expression, the type of actual generic parameters, and + the values of constraints characterizing the subtype of actual parameters. + </td> + <td class="yn">partial</td> + <td class="yn">partial?</td> + <td class="yn">no</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 11D. Object System Configuration. The object system configuration must be explicitly + specified in each separately translated unit. Such specifications must include the + object machine model, the operating system if present, peripheral equipment, and the + device configuration, and may include special hardware options and memory size. The + translator will use such specifications when generating object code. [Note that programs + that depend on the specific characteristics of the object machine, may be made more + portable by enclosing those portions in branches of conditionals on the object machine + configuration.] + </td> + <td class="yn">no?</td> + <td class="yn">no?</td> + <td class="yn">no</td> + <td class="yn">no?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 11E. Interface to Other Languages. There shall be a machine independent interface to + other programming languages including assembly languages. Any program element that is + referenced in both the source language program and foreign code must be identified in + the interface. The source language of the foreign code must also be identified. + </td> + <td class="yn">yes</td> + <td class="yn">no</td> + <td class="yn">mostly</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + D provides interfaces to C, C++ and assembly. Many Pascal implementations provide + interfaces to C and assembly. Parasail provides no interfaces to other languages. Rust + provides an interface to C and assembly. + </td> + </tr> + + <tr> + <td rowspan="2"> + 11F. Optimization. Programs may advise translators on the optimization criteria to be + used in a scope. It shall be possible in programs to specify whether minimum translation + costs or minimum execution costs are more important, and whether execution time or + memory space is to be given preference. All such specifications shall be optional. + Except for the amount of time and space required during execution, approximate values + beyond the specified precision, the order in which exceptions are detected, and the + occurrence of side effects within an expression, optimization shall not alter the + semantics of correct programs, (e.g., the semantics of parameters will be unaffected by + the choice between open and closed calls). + </td> + <td class="yn">partial?</td> + <td class="yn">no?</td> + <td class="yn">partial?</td> + <td class="yn">partial?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 12A. Library. There shall be an easily accessible library of generic definitions and + separately translated units. All predefined definitions shall be in the library. Library + entries may include those used as input-output packages, common pools of shared + declarations, application oriented software packages, encapsulations, and machine + configuration specifications. The library shall be structured to allow entries to be + associated with particular applications, projects, and users. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 12B. Separately Translated Units. Separately translated units may be assembled into + operational systems. It shall be possible for a separately translated unit to reference + exported definitions of other units. All language imposed restrictions shall be enforced + across such interfaces. Separate translation shall not change the semantics of a correct + program. + </td> + <td class="yn">mostly?</td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 12D. Generic Definitions. Functions, procedures, types, and encapsulations may have + generic parameters. Generic parameters shall be instantiated during translation and + shall be interpreted in the context of the instantiation. An actual generic parameter + may be any defined identifier (including those for variables, functions, procedures, + processes, and types) or the value of any expression. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + Rust only accepts types as generic parameters. Standard Pascal does not support + generics, but later Pascal derivatives such as Free Pascal and Delphi both do. + </td> + </tr> + + <tr> + <td rowspan="2"> + 13A. Defining Documents. The language shall have a complete and unambiguous defining + document. It should be possible to predict the possible actions of any syntactically + correct program from the language definition. The language documentation shall include + the syntax, semantics, and appropriate examples of each built-in and predefined feature. + A recommended set of translation diagnostic and warning messages shall be included in + the language definition. + </td> + <td class="yn">mostly?</td> + <td class="yn">mostly?</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 13B. Standards. There will be a standard definition of the language. Procedures will be + established for standards control and for certification that translators meet the + standard. + </td> + <td class="yn">no</td> + <td class="yn">no</td> + <td class="yn">yes</td> + <td class="yn">no</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 13C. Completeness of Implementations. Translators shall implement the standard + definition. Every translator shall be able to process any syntactically correct program. + Every feature that is available to the user shall be defined in the standard, in an + accessible library, or in the source program. + </td> + <td class="yn">mostly?</td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 13D. Translator Diagnostics. Translators shall be responsible for reporting errors that + are detectable during translation and for optimizing object code. Translators shall be + responsible for the integrity of object code in affected translation units when any + separately translated unit is modified, and shall ensure that shared definitions have + compatible representations in all translation units. Translators shall do full syntax + and type checking, shall check that all language imposed restrictions are met, and + should provide warnings where constructs will be dangerous or unusually expensive in + execution and shall attempt to detect exceptions during translation. If the translator + determines that a call on a routine will not terminate normally, the exception shall be + reported as a translation error at the point of call. + </td> + <td class="yn">mostly?</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes?</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 13E. Translator Characteristics. Translators for the language will be written in the + language and will be able to produce code for a variety of object machines. The machine + independent parts of translators should be separate from code generators. Although it is + desirable, translators need not be able to execute on every object machine. The internal + characteristics of the translator (i.e., the translation method) shall not be specified + by the language definition or standards. + </td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + <td class="yn">mostly</td> + </tr> + <tr> + <td colspan="4"> + Many, but not all, compilers are written in their own language. Parasail and Rust both + have one compiler each, both written in their respective language. + </td> + </tr> + + <tr> + <td rowspan="2"> + 13F. Restrictions on Translators. Translators shall fail to translate otherwise correct + programs only when the program requires more resources during translation than are + available on the host machine or when the program calls for resources that are + unavailable in the specified object system configuration. Neither the language nor its + translators shall impose arbitrary restrictions on language features. For example, they + shall not impose restrictions on the number of array dimensions, on the number of + identifiers, on the length of identifiers, or on the number of nested parentheses + levels. + </td> + <td class="yn">yes</td> + <td class="yn">yes</td> + <td class="yn">yes?</td> + <td class="yn">yes</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> + + <tr> + <td rowspan="2"> + 13G. Software Tools and Application Packages. The language should be designed to work in + conjunction with a variety of useful software tools and application support packages. + These will be developed as early as possible and will include editors, interpreters, + diagnostic aids, program analyzers, documentation aids, testing aids, software + maintenance tools, optimizers, and application libraries. There will be a consistent + user interface for these tools. Where practical software tools and aids will be written + in the language. Support for the design, implementation, distribution, and maintenance + of translators, software tools and aids, and application libraries will be provided + independently of the individual projects that use them. + </td> + <td class="yn">mostly</td> + <td class="yn">partial</td> + <td class="yn">yes</td> + <td class="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> +</table> + + </div> +</div> +{% endblock -%} + + |