more language stuff

gistfile1.hs

data BExp = TRUE 
          | FALSE 
          | AND BExp BExp 
          | OR BExp BExp
          | NOT BExp
          | QUANT QExp

beval :: BExp -> Bool

beval TRUE = True
beval FALSE = False

beval (AND left right) = (beval left) && (beval right)
beval (OR left right) = (beval left) || (beval right)
beval (NOT ex) = not (beval ex)

beval (QUANT ex) = (qeval ex)


data AExp = I Integer 
          | PLUS AExp AExp 
          | SUB AExp AExp 
          | MULTI AExp AExp 
          | DIV AExp AExp

aeval :: AExp -> Integer

aeval (I i) = i

aeval (PLUS left right) = (aeval left) + (aeval right)
aeval (SUB left right) = (aeval left) - (aeval right)
aeval (MULTI left right) = (aeval left) * (aeval right)
aeval (DIV left right) = (aeval left) `div` (aeval right)

data QExp = GR AExp AExp
          | LE AExp AExp
          | EQU AExp AExp
          | NEQ AExp AExp
          | LEQ AExp AExp
          | GEQ AExp AExp

qeval :: QExp -> Bool

qeval (GR left right) = (aeval left) > (aeval right)
qeval (LE left right) = (aeval left) < (aeval right)
qeval (EQU left right) = (aeval left) == (aeval right)
qeval (NEQ left right) = (aeval left) /= (aeval right)
qeval (LEQ left right) = (aeval left) <= (aeval right)
qeval (GEQ left right) = (aeval left) >= (aeval right)


data CExp = IF BExp AExp AExp

ceval :: CExp -> Integer

ceval (IF pred valid invalid) | (beval pred) = (aeval valid)
                              | otherwise = (aeval invalid)


test =  (ceval 
            (IF 
                (NOT 
                    (QUANT 
                        (GR 
                            (PLUS (I 1) (I 1)) 
                            (MULTI (I 2) (I 1))
                        )
                    )
                )
                (SUB (I 3) (I 2))
                (DIV (I 6) (I 2))
            )
        )