[Haskell-cafe] Very crazy
Brandon S. Allbery KF8NH
allbery at ece.cmu.edu
Tue Sep 25 09:25:23 EDT 2007
On Sep 25, 2007, at 7:25 , Andrew Coppin wrote:
> Chaddaï Fouché wrote:
>> 2007/9/25, Andrew Coppin <andrewcoppin at btinternet.com>:
>>>> printf don't always perform IO : if you ask it for a String it will
>>>> happily turn into sprintf for you, if you use it in the IO
>>>> Monad, it
>>>> will indeed perform IO, but there's nothing fundamentally IO
>>>> bound in
>>>> printf logic.
>>> That's even *more* impossible... o_O
>> Why ?
> How can one function have more than one type signature?
Polymorphism via typeclasses. PrintfType is rather hairy, as I said,
but it can do the job by having instances for IsString (itself a hack
of sorts) and IO.
brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery at kf8nh.com
system administrator [openafs,heimdal,too many hats] allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university KF8NH
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