From 0ee94c3bc29f75dd4985340781e3c53a0c867fca Mon Sep 17 00:00:00 2001
From: darkf <lw9k123@gmail.com>
Date: Fri, 18 Oct 2013 13:24:00 -0700
Subject: [PATCH] add a list constant/type

---
 interp.hs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/interp.hs b/interp.hs
index 6382ccb..73ec0cf 100644
--- a/interp.hs
+++ b/interp.hs
@@ -6,6 +6,7 @@ data AST = Add AST AST
 		 | Var String
 		 | Lambda [(Pattern, [AST])]
 		 | Call String [AST]
+		 | ListConst [AST]
 		 | StrConst String
 		 | IntConst Int
 		 deriving (Show, Eq)
@@ -16,6 +17,7 @@ data Pattern = VarP String
 
 data Value = IntV Int
 		   | StrV String
+		   | ListV [Value]
 		   | FnV [(Pattern, [AST])] -- pattern->body bindings
 		   deriving (Show, Eq)
 
@@ -33,6 +35,10 @@ eval :: AST -> InterpState Value
 eval (IntConst i) = return $ IntV i
 eval (StrConst s) = return $ StrV s
 
+eval (ListConst v) =
+	mapM eval v >>= \xs ->
+		return $ ListV xs
+
 eval (Var var) = get >>= \m ->
   case M.lookup var m of
     Just v -> return v
@@ -98,6 +104,7 @@ main = do
 	print $ evalProgram prg
 	print $ evalProgram prg2
 	print $ evalProgram prg3
+	print $ evalProgram prg4
 	where
 		prg = [Def "x" (IntConst 5),
 			   Def "y" (IntConst 3),
@@ -110,4 +117,5 @@ main = do
 				 					(IntP 1, [IntConst 200]),
 				 					(VarP "x", [IntConst 300])
 				 				  ],
-				 Call "f" [IntConst 2]]
\ No newline at end of file
+				 Call "f" [IntConst 2]]
+		prg4 = [ Def "lst" (ListConst [IntConst 1, IntConst 2, IntConst 3]) ]
\ No newline at end of file