On Dec 25, 2007 4:27 PM, Henning Thielemann
<[EMAIL PROTECTED]> 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.
$ cat t.hs
module Main where
instance Integral Double
test :: (Integral a, RealFrac a) => a
test =
let c = undefined
in asTypeOf (round c) c
main = print (test :: Double)
$ ghc --make t.hs
[1 of 1] Compiling Main ( t.hs, t.o )
t.hs:3:0:
Warning: No explicit method nor default method for `quotRem'
In the instance declaration for `Integral Double'
t.hs:3:0:
Warning: No explicit method nor default method for `toInteger'
In the instance declaration for `Integral Double'
Linking t ...
$ ./t
t: Prelude.undefined
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.6.1
--
Felipe.
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