[Haskell-cafe] wildcards for type variables?

Brandon S. Allbery KF8NH allbery at ece.cmu.edu
Wed Jan 13 05:59:09 EST 2010

On Jan 13, 2010, at 05:54 , David Virebayre wrote:
> On Wed, Jan 13, 2010 at 12:29 AM, Evan Laforge <qdunkan at gmail.com>  
> wrote:
>> Occasionally I have a function with an unused argument, whose type I
>> don't want to restrict.  Thus:
>> f :: _unused -> A -> B
>> f _ a = b
> I probably misunderstood the problem, why not f:: a -> A -> B

He's looking for the self-documentation aspect of "this argument is  
completely irrelevant".  Neither rolling a random unused type variable  
nor "forall"ing it (my first idea) really accomplishes that.

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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