From c71774e0dfd81df81f2de5a7f2c9a5f703bac9b2 Mon Sep 17 00:00:00 2001
From: Jed Barber <jjbarber@y7mail.com>
Date: Tue, 11 Mar 2014 19:39:23 +1100
Subject: Added support for @,|,?

---
 Unlambda/Interpreter.hs | 64 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 39 insertions(+), 25 deletions(-)

diff --git a/Unlambda/Interpreter.hs b/Unlambda/Interpreter.hs
index c9820f0..362d57a 100644
--- a/Unlambda/Interpreter.hs
+++ b/Unlambda/Interpreter.hs
@@ -3,6 +3,7 @@ module Unlambda.Interpreter (
     ) where
 
 
+import System.IO.Error
 import Control.Exception( Exception(..), Handler(..), throw, catches )
 import Data.Typeable
 import Unlambda.Parser
@@ -19,61 +20,74 @@ instance Control.Exception.Exception UnlambdaException
 
 unlambda :: UnlambdaTerm -> IO UnlambdaTerm
 unlambda term = 
-    catches (eval term)
+    catches (eval Nothing term)
             [ Handler ((\e -> return (endTerm e)) :: UnlambdaException -> IO UnlambdaTerm) ]
 
 
 
-eval :: UnlambdaTerm -> IO UnlambdaTerm
-eval term =
+eval :: Maybe Char -> UnlambdaTerm -> IO UnlambdaTerm
+eval ch term =
     case term of
         App f x -> do
-            t <- eval f
-            apply t x
+            t <- eval ch f
+            apply ch t x
         _ -> return term
 
 
 
-apply :: UnlambdaTerm -> UnlambdaTerm -> IO UnlambdaTerm
-apply firstTerm secondTerm =
+apply :: Maybe Char -> UnlambdaTerm -> UnlambdaTerm -> IO UnlambdaTerm
+apply ch firstTerm secondTerm =
     case firstTerm of
-        K -> eval secondTerm >>= return . Kpartial
+        K -> eval ch secondTerm >>= return . Kpartial
 
-        Kpartial x -> eval secondTerm >> return x
+        Kpartial x -> eval ch secondTerm >> return x
 
-        S -> eval secondTerm >>= return . Spartial
+        S -> eval ch secondTerm >>= return . Spartial
 
-        Spartial x -> eval secondTerm >>= return . (Sapp x)
+        Spartial x -> eval ch secondTerm >>= return . (Sapp x)
 
         Sapp x y -> do
-            z <- eval secondTerm
-            result <- eval (App (App x z) (App y z))
+            z <- eval ch secondTerm
+            result <- eval ch (App (App x z) (App y z))
             return result
 
-        I -> eval secondTerm
+        I -> eval ch secondTerm
 
-        V -> eval secondTerm >> return V
+        V -> eval ch secondTerm >> return V
 
         C -> return I --placeholder
 
         D -> return (Promise secondTerm)
 
         Promise x -> do
-            y <- eval secondTerm
-            result <- eval (App x y)
+            y <- eval ch secondTerm
+            result <- eval ch (App x y)
             return result
 
-        Dot c -> putChar c >> eval secondTerm
+        Dot c -> putChar c >> eval ch secondTerm
 
-        R -> putChar '\n' >> eval secondTerm
+        R -> putChar '\n' >> eval ch secondTerm
 
         E -> do
-            t <- eval secondTerm
+            t <- eval ch secondTerm
             throw (UnlambdaException t)
 
-        Reed -> return I --placeholder
-
-        Bar -> return I --placeholder
-
-        Compare c -> return I --placeholder
+        Reed -> do
+            t <- eval ch secondTerm
+            catchIOError (do
+                ch' <- getChar
+                eval (Just ch') (App t I)
+                ) (\e -> eval Nothing (App t V))
+
+        Bar -> do
+            t <- eval ch secondTerm
+            case ch of
+                Just x -> eval ch (App t (Dot x))
+                Nothing -> eval ch (App t V)
+
+        Compare c -> do
+            t <- eval ch secondTerm
+            case (ch == Just c) of
+                True -> eval ch (App t I)
+                False -> eval ch (App t V)
 
-- 
cgit