[Haskell-cafe] ambiguous types although 'asTypeOf'

[Henning Thielemann]

On Tue, 25 Dec 2007, Felipe Lessa wrote:

> On Dec 25, 2007 4:27 PM, Henning Thielemann
> <lemming at henning-thielemann.de> wrote:
> > test :: (Integral a, RealFrac a) => a
> > test =
> >    let c = undefined
> >    in  asTypeOf (round c) c
> >
> >
> > When compiling I get:
> >
> > Compiling StorableInstance ( src/StorableInstance.hs, interpreted )
> >
> > src/StorableInstance.hs:38:17:
> >     Warning: Defaulting the following constraint(s) to type `Double'
> >              `RealFrac a' arising from use of `round' at src/StorableInstance.hs:38:17-21
> >              In the first argument of `asTypeOf', namely `(round c)'
> >              In the definition of `test1': test1 = let c = undefined in asTypeOf (round c) c
>
> Interesting, I don't see this behaviour at all.

Of course, I use -Wall all the time. :-)