Made Interpreter exportable

With multistep, stepText, interpretText functions

Author: cadsit

Grammar.y

@@ -1,5 +1,5 @@
 {
-module Parser (Exp(..), AppExp(..), Value(..), Var(..), parseFromFile) where
+module Parser (Exp(..), AppExp(..), Value(..), Var(..), parse, parseFromFile) where
 import Scanner
 }
 
@@ -113,5 +113,5 @@ instance Show Value where
 parseFromFile fil =
    do
       toks <- Scanner.lexFromFile fil
-      return (p_lam toks)
+      return (parse toks)
 }

Interpreter.hs

@@ -6,7 +6,8 @@
    Provides Operational Semantics for basic Lambda Calculus
 -}
 
-module Interpreter where
+module Interpreter (stepExp, multistepExp, stepText, interpretText) where
+import Scanner
 import Parser
 
 -- Checks to see if an expression cannot be evaluated more
@@ -234,3 +235,22 @@ stepAppExp ae =
                            Just val -> Nothing
      -- A value cannot take a step
      Parser.Value v -> Nothing
+
+multistepExp :: Parser.Exp -> Parser.Exp
+multistepExp exp =
+   let exp' = stepExp exp
+   in case exp' of
+      Nothing    -> exp
+      Just exp'' -> multistepExp exp''
+
+stepText :: String -> Maybe Parser.Exp
+stepText str = 
+   let toks = Scanner.alexScanTokens str
+       exp = Parser.parse toks
+   in stepExp exp
+
+interpretText :: String -> Parser.Exp
+interpretText str =
+   let toks = Scanner.alexScanTokens str
+       exp = Parser.parse toks
+   in multistepExp exp

Lexer.x

@@ -43,10 +43,10 @@ data Token =
    deriving (Eq,Show)
 
 lexFromFile fil = 
-   do
-      s <- readFile fil
-      let toks = (alexScanTokens s)
-      return toks
+      do 
+         s <- readFile fil
+	 let toks = (alexScanTokens s)
+	 return toks
 
 lexFromFileToFile infile outfile = 
    do

Parser.hs

@@ -1,5 +1,5 @@
 {-# OPTIONS_GHC -w #-}
-module Parser (Exp(..), AppExp(..), Value(..), Var(..), parseFromFile) where
+module Parser (Exp(..), AppExp(..), Value(..), Var(..), parse, parseFromFile) where
 import Scanner
 
 -- parser produced by Happy Version 1.18.9
@@ -355,7 +355,7 @@ happyReturn1 = \a tks -> (return) a
 happyError' :: () => [(Scanner.Token)] -> HappyIdentity a
 happyError' = HappyIdentity . parseError
 
-p_lam tks = happyRunIdentity happySomeParser where
+parse tks = happyRunIdentity happySomeParser where
   happySomeParser = happyThen (happyParse action_0 tks) (\x -> case x of {HappyAbsSyn4 z -> happyReturn z; _other -> notHappyAtAll })
 
 happySeq = happyDontSeq
@@ -426,7 +426,7 @@ instance Show Value where
 parseFromFile fil =
    do
       toks <- Scanner.lexFromFile fil
-      return (p_lam toks)
+      return (parse toks)
 {-# LINE 1 "templates/GenericTemplate.hs" #-}
 {-# LINE 1 "templates/GenericTemplate.hs" #-}
 {-# LINE 1 "<built-in>" #-}

Scanner.hs

@@ -177,10 +177,10 @@ data Token =
    deriving (Eq,Show)
 
 lexFromFile fil = 
-   do
-      s <- readFile fil
-      let toks = (alexScanTokens s)
-      return toks
+      do 
+         s <- readFile fil
+	 let toks = (alexScanTokens s)
+	 return toks
 
 lexFromFileToFile infile outfile = 
    do

test-files/test0.lc

@@ -0,0 +1 @@
+&&&