Hi,
It seems that I need to distinguish between a theory for Haskell and a
given implementation (GHCi). I have two further queries based on the
replies;
1)
> Obviously I get two different types
> Wrong. You get exactly the same type, it's just that GHCi detected that you
> have a fancy name for this type, so it gives you that name. It's not type
> system, it's just GHCi.
Are you saying there is just one type? (not two isomorphic types because
there is only one of them with two names)
2)
>> In the case of the function Haskells type system seems to pick up enough
>> > information to determine that “ww” is a Name.
>
> Nope. "ww" is still a [Char] for the compiler. And you do not even check for
> the type of "ww".
>
> :t snd . (\x -> (getName x, x)) $ "ww"
> ... :: String
Why are the GHCi commands :t "ww" and :t getName("ww") not a valid type
checks?
Pat
pbrowne wrote:
> Hi,
> I am studying the underlying semantics behind Haskell and to what degree
> those semantics are actually implemented. I need to clarify what a *type
> synonym* actual means in relation to Haskell's logic (or formal
> semantics). I used the following type synonym:
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