Shell to C translator (using new intermediate represantation)

task2.hs

import IR

type C = String

genC x = helper "" "" 0 x
  where helper :: C -> C -> Int -> Statement -> C
        
        helper defs code n (Sequence (x:[])) = helper (defs ++ genDefs n True x) (code ++ genCode n True x) (n + countDefs x) (Sequence [])
        helper defs code n (Sequence (x:xs)) = helper (defs ++ genDefs n False x) (code ++ genCode n False x) (n + countDefs x) (Sequence xs)
        helper defs code n (Sequence _     ) = "#include \"routines.h\"\nint main(){" ++ defs ++ code ++ "}"

        helper defs code n (Command x xs) = "#include \"routines.h\"\nint main(){" ++ genDefs 0 True (Command x xs) ++ genCode 0 True (Command x xs) ++ "}"

        countDefs :: Statement -> Int
        countDefs (Command _ _) = 1
        countDefs _ = 0

        genDefs :: Int -> Bool -> Statement -> C
        genDefs n return (Command (ConcatA x) _) = "const char* cmd" ++ show n ++ "[] = { " ++ fromConcatA x ++ "NULL };" ++ (if return then "int retval;" else "")
        genDefs n return (Command x _) = "const char* cmd" ++ show n ++ "[] = { " ++ fromArray x ++ "NULL };" ++ (if return then "int retval;" else "")
        genDefs n return x = "genDefs: n=" ++ show n ++ ", x=" ++ show x ++ ""

        fromConcatA :: [Array] -> C
        fromConcatA ((Field x):[]) = "\"" ++ parseExpression x ++ "\", "
        fromConcatA ((Field x):xs) = "\"" ++ parseExpression x ++ "\", " ++ fromConcatA xs
        fromConcatA _         = ""

        fromArray :: Array -> C
        fromArray (Field x) = "\"" ++ parseExpression x ++ "\", "
        fromArray _ = ""

        parseExpression :: Expression -> C
        parseExpression (Const x) = x
        parseExpression _         = ""

        genCode :: Int -> Bool -> Statement -> C
        genCode n return (Command (ConcatA x) _) = (if return then "retval=" else "") ++ "exec_command (cmd" ++ show n ++ ");" ++ (if return then "return retval;" else "")
        genCode n return (Command x _) = (if return then "retval=" else "") ++ "exec_command (cmd" ++ show n ++ ");" ++ (if return then "return retval;" else "")
        genCode n return x = "genCode: n=" ++ show n ++ ", x=" ++ show x ++ ""


main = putStr (genC ( Sequence [ Command (ConcatA [Field (Const "ping"),Field (Const "-c5"),Field (Const "google.com")]) [], Command (Field (Const "date")) [], Command (ConcatA [Field (Const "tuch"),Field (Const "example.file")]) [], Command (Field (Const "ncal")) [], Command (ConcatA [Field (Const "echo"),Field (Const "Hello, world!")]) [] ] ) )
--main = putStr (genC (Command (Field (Const "date")) []))
--main = putStr (genC (Sequence [(Command (ConcatA [Field (Const "ping"),Field (Const "google.com")]) [])]))