how do I abstract this pattern ?
Brandon S. Allbery KF8NH
allbery at ece.cmu.edu
Wed May 21 16:55:32 EDT 2008
On 2008 May 21, at 12:31, Bulat Ziganshin wrote:
> Wednesday, May 21, 2008, 8:11:56 PM, you wrote:
>> Suppose p1, p2, p3 are 3 predicates
>> that take an input -- say, a String.
>> They return either (True, result)
>> or False.
> if they return Just result or Nothing - yes, use Maybe as monad:
> combine p1 p2 p3 x= do x1 <- p1 x
> x2 <- p2 x1
> x3 <- p3 x2
> return x3
S/He's not passing on r (the result), but s (the argument). Monad ((-
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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