added imptest.y, other small changes

#Imp.ast#

-module AST where
-type ID = String
-
-data Prog = Prog [AST]
-
-data AST = Expression Exp 
-         | TopLevlDec Dec 
-
-data Exp = SET ID Exp  
-    | IF SimpleExp Exp (Maybe Exp)  
-    | WHILE SimpleExp Exp  
-    | BEGIN (List1 Exp)
-    | LET [(String, Exp)] Exp
-    
-data BinOp = Plus SimpleExp SimpleExp  
-           | Mult SimpleExp SimpleExp  
-           | Div SimpleExp SimpleExp  
-           | Minus SimpleExp SimpleExp  
-           | CheckExpect SimpleExp SimpleExp  
-    
-data SimpleExp = 
-        Lit Int  
-      | Var ID  
-      | Apply ID (List0 Exp)
-      | BinOp BinOp
---      | AGet SimpleExp SimpleExp --(arr[i])
---      | ASet SimpleExp SimpleExp SimpleExp --(set arr[i] j)
---      | AMake ID SimpleExp  --(new arr size)
-
-data Dec = Val ID Exp

.#Imp.ast

-matt@hal.2957:1457926303
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