Lambda

[fp.git] / Lambda.hs

diff --git a/lambda.hs b/Lambda.hs
similarity index 77%
rename from lambda.hs
rename to Lambda.hs
index 356412d..d9bdaee 100644 (file)
--- a/lambda.hs
+++ b/Lambda.hs
@@ -1,15 +1,19 @@
+module Lambda where
+

 import Data.Text as T
 import Data.Attoparsec.Text
 import Control.Applicative
 
 import Data.Text as T
 import Data.Attoparsec.Text
 import Control.Applicative
 

-data Term = Var String | Lambda Term Term | App Term Term
+type VarName = String
+data Term = Var VarName | Lambda VarName Term | App Term Term

 
 instance Show Term where
   show (Var x) = x
 
 instance Show Term where
   show (Var x) = x

-  show (Lambda (Var x) t) = "\\" ++ x ++ "." ++ show t
+  show (Lambda x t) = "\\" ++ x ++ "." ++ show t

   show (App t r) = "(" ++ show t ++ " " ++ show r ++ ")"
 
 --instance Read Term where
   show (App t r) = "(" ++ show t ++ " " ++ show r ++ ")"
 
 --instance Read Term where

+tRead :: String -> Term

 tRead s = case parseOnly (parseTerm <* endOfInput) (T.pack s) of
     (Right t) -> t
     (Left e) -> error e
 tRead s = case parseOnly (parseTerm <* endOfInput) (T.pack s) of
     (Right t) -> t
     (Left e) -> error e


@@ -22,12 +26,11 @@ parseVar = do
 parseLambda :: Parser Term
 parseLambda = do
   char '\\'
 parseLambda :: Parser Term
 parseLambda = do
   char '\\'

-  x <- parseVar
+  (Var x) <- parseVar

   char '.'
   t <- parseTerm
   return $! Lambda x t
 
   char '.'
   t <- parseTerm
   return $! Lambda x t
 

-

 parseApp :: Parser Term
 parseApp = do
   char '('
 parseApp :: Parser Term
 parseApp = do
   char '('