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| author | Jed Barber <jjbarber@y7mail.com> | 2017-10-29 14:36:03 +1100 |
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| committer | Jed Barber <jjbarber@y7mail.com> | 2017-10-29 14:36:03 +1100 |
| commit | 3600dd56ee6d7d9bfff3e7f8f8a327e601be5ca3 (patch) | |
| tree | bfb57da410b0c9efa789e9d0e8a9d333a064ac61 /project/templates | |
| parent | 2a0b860b4febe9af9bcaa07e0b1f64371dd326fb (diff) | |
Article for D, Parasail, Pascal, and Rust vs The Steelman added
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diff --git a/project/templates/index.html b/project/templates/index.html index 7180af6..df1de33 100644 --- a/project/templates/index.html +++ b/project/templates/index.html @@ -16,6 +16,9 @@ {% block content %} <ul class="index"> + <li><a href="/steelman.html">D, Parasail, Pascal, and Rust vs The Steelman</a><br> + <span class="post">(Posted 29/10/2017)</span></li> + <li><a href="/sokoban.html">Sokoban Clone</a><br> <span class="post">(Posted 8/8/2017)</span></li> diff --git a/project/templates/steelman.html b/project/templates/steelman.html new file mode 100644 index 0000000..175076f --- /dev/null +++ b/project/templates/steelman.html @@ -0,0 +1,2318 @@ + +{% extends "base.html" %} + + + +{% 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" target="_blank">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/" target="_blank">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/" target="_blank">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-multicoreIt provides an example of a possible" target="_blank">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)" target="_blank">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" target="_blank">teaching algorithms</a>. +Later dialects were used to develop several high profile software projects, including Skype, Photoshop, and parts of +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/" target="_blank">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" target="_blank">affine typing</a>.</p> + +<table id="lang"> + <tr> + <td> + <figure> + <img src="/img/logo_d_small.png" + alt="Logo for the D programming language" + height="124" + width="164"> + <figcaption>D</figcaption> + </figure> + </td> + <td> + <figure> + <img src="/img/logo_parasail_small.png" + alt="Logo for the Parasail programming language" + height="144" + width="149"> + <figcaption>Parasail</figcaption> + </figure> + </td> + </tr> + <tr> + <td> + <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"> + <figcaption>Pascal*</figcaption> + </figure> + </td> + <td> + <figure> + <img src="/img/logo_rust_small.png" + alt="Logo for the Rust programming language" + height="144" + width="144"> + <figcaption>Rust</figcaption> + </figure> + </td> + </tr> +</table> + +<p>* Pascal does not have an official logo, so a picture of <a href="https://en.wikipedia.org/wiki/Blaise_Pascal" target="_blank">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" target="_blank">D Language Specification</a> and the + accompanying <a href="https://dlang.org/phobos/index.html" target="_blank">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" target="_blank">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" target="_blank">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/" target="_blank">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/" target="_blank">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> + +<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 id="yn">yes</td> + <td id="yn">no?</td> + <td id="yn">yes?</td> + <td id="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 id="yn">yes?</td> + <td id="yn">yes</td> + <td id="yn">partial?</td> + <td id="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 id="yn">partial?</td> + <td id="yn">yes?</td> + <td id="yn">mostly?</td> + <td id="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 id="yn">partial?</td> + <td id="yn">yes?</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes?</td> + <td id="yn">mostly</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">mostly?</td> + <td id="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 id="yn">mostly</td> + <td id="yn">mostly</td> + <td id="yn">mostly</td> + <td id="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 id="yn">partial?</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">mostly</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">mostly?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">partial</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">partial?</td> + <td id="yn">yes</td> + <td id="yn">yes?</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">yes?</td> + <td id="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 id="yn">partial</td> + <td id="yn">yes?</td> + <td id="yn">mostly?</td> + <td id="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 id="yn">partial?</td> + <td id="yn">yes</td> + <td id="yn">partial?</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">mostly</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">no</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes?</td> + <td id="yn">partial</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">partial</td> + <td id="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 id="yn">no</td> + <td id="yn">yes</td> + <td id="yn">no</td> + <td id="yn">no</td> + </tr> + <tr> + <td colspan="4"> + Of these four languages, inly 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 id="yn">no</td> + <td id="yn">yes</td> + <td id="yn">no</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes?</td> + <td id="yn">yes?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes?</td> + <td id="yn">no</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">no?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes?</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes?</td> + <td id="yn">yes?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes?</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly?</td> + <td id="yn">yes?</td> + <td id="yn">mostly?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes?</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">no</td> + <td id="yn">no</td> + <td id="yn">no?</td> + <td id="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 id="yn">partial</td> + <td id="yn">partial</td> + <td id="yn">partial?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">partial</td> + <td id="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 id="yn">mostly</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes?</td> + <td id="yn">partial</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">mostly</td> + <td id="yn">mostly?</td> + <td id="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 id="yn">partial</td> + <td id="yn">yes</td> + <td id="yn">partial?</td> + <td id="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 id="yn">yes?</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">no</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 (l.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 id="yn">no</td> + <td id="yn">yes</td> + <td id="yn">yes?</td> + <td id="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 id="yn">partial?</td> + <td id="yn">no?</td> + <td id="yn">partial?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">mostly</td> + <td id="yn">partial</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">yes</td> + <td id="yn">mostly</td> + <td id="yn">no</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">no</td> + <td id="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 id="yn">partial?</td> + <td id="yn">yes</td> + <td id="yn">no</td> + <td id="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 id="yn">yes?</td> + <td id="yn">yes?</td> + <td id="yn">no</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes?</td> + <td id="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 id="yn">yes</td> + <td id="yn">no?</td> + <td id="yn">no</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">no</td> + <td id="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 id="yn">mostly?</td> + <td id="yn">mostly?</td> + <td id="yn">no</td> + <td id="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 id="yn">mostly?</td> + <td id="yn">mostly?</td> + <td id="yn">no</td> + <td id="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 id="yn">yes</td> + <td id="yn">partial?</td> + <td id="yn">partial?</td> + <td id="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 id="yn">partial?</td> + <td id="yn">mostly</td> + <td id="yn">partial</td> + <td id="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 id="yn">yes</td> + <td id="yn">partial</td> + <td id="yn">partial</td> + <td id="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 id="yn">yes</td> + <td id="yn">no?</td> + <td id="yn">partial</td> + <td id="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 id="yn">yes?</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly</td> + <td id="yn">mostly</td> + <td id="yn">no</td> + <td id="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 id="yn">partial</td> + <td id="yn">no</td> + <td id="yn">no</td> + <td id="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 id="yn">partial?</td> + <td id="yn">no?</td> + <td id="yn">no</td> + <td id="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 id="yn">partial</td> + <td id="yn">partial?</td> + <td id="yn">no</td> + <td id="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 id="yn">no?</td> + <td id="yn">no?</td> + <td id="yn">no</td> + <td id="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 id="yn">yes</td> + <td id="yn">no</td> + <td id="yn">mostly</td> + <td id="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 id="yn">partial?</td> + <td id="yn">no?</td> + <td id="yn">partial?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly?</td> + <td id="yn">yes?</td> + <td id="yn">yes?</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">partial</td> + <td id="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 id="yn">mostly?</td> + <td id="yn">mostly?</td> + <td id="yn">yes</td> + <td id="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 id="yn">no</td> + <td id="yn">no</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly?</td> + <td id="yn">yes</td> + <td id="yn">yes</td> + <td id="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 id="yn">mostly?</td> + <td id="yn">yes</td> + <td id="yn">yes?</td> + <td id="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 id="yn">mostly</td> + <td id="yn">mostly</td> + <td id="yn">mostly</td> + <td id="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 id="yn">yes</td> + <td id="yn">yes</td> + <td id="yn">yes?</td> + <td id="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 id="yn">mostly</td> + <td id="yn">partial</td> + <td id="yn">yes</td> + <td id="yn">partial</td> + </tr> + <tr> + <td colspan="4"> + </td> + </tr> +</table> + +{% endblock %} + + |