c8h10n4o2 wrote:
The problem is there. A function in Hai would be function-name, arg1,argn=body. Func stores function name,arguments and body as Strings(I was thinking to put Func String String String). The parser func that I wrote so far try to parse a function definition, not a function call. But when I try to store the function on my Map I get a error with somthing called 'functional dependencies'(which I don't know what is).
You mean: hai1.hs:41:6: Couldn't match expected type `Hai' against inferred type `[Hai]' Expected type: Map.Map Hai Hai Inferred type: Map.Map [Hai] Hai When using functional dependencies to combine MonadState (Map.Map [Hai] Hai) m, arising from a use of `get' at hai1.hs:52:17-19 MonadState (Map.Map Hai Hai) m, arising from a use of `get' at hai1.hs:47:16-18 When generalising the type(s) for `w' The type checker tells you that you are using the same Map with different key types: at 52:17-19 the key has type [Hai], whereas at 47:16-18 it has type Hai. The latter is in your Func case: e <-return $ Map.insert (a :[b]) c d where you use a :[b] which is the same as [a,b] for the key. Everywhere else, the key has type Hai. This in itself is questionable: do you really want to use arbitrary expressions as keys? Usually one would have a Map String Hai representing a map from variable (or function) names to expressions. For functions you then want data Hai = ... | Func [String] Hai | ... so that Func args body represents the (anonymous) function with the formal arguments args and the resulting expression body . The function gets a name by inserting it into the variable map. This means that a definition function-name,arg1,...,argn=body actually defines a variable named "function-name" which, when it gets looked up in the environment, yields the value Func [arg1,...,argn] body . Cheers Ben