[Haskell-cafe] understanding typeable
Anatoly Yakovenko
aeyakovenko at gmail.com
Mon Apr 13 01:18:40 EDT 2009
ah, Int vs Integer, i didn't see that at all. Thats kind of weird, i
thought 1 could be either one. This works
> funResultTy (typeOf FooC) (typeOf (1::Int))
Just ParseG.Foo
but
> funResultTy (typeOf FooC) (typeOf $ fromIntegral 1)
Nothing
doesn't
so, how do i actually do something with this? is there a way that i
can pull out the computation? Like there is a -> TypeRep, is there a
TypeRep -> a function? cast doesn't seem to do what i want
> let a::Foo = fromJust $ cast $ fromJust $ funResultTy (typeOf FooC) (typeOf (1::Int))
> a
*** Exception: Maybe.fromJust: Nothing
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