Re: [Haskell-cafe] How to spot Monads, Applicatives ...

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martin writes:

I am at a stage, where I can use some of the Monads and Applicatives which are out there. But I hardly ever wrote my own instances. I am curious to learn about the thought processes which lead to the insight "hey that can be written nicely as an Applicative Functor"

When I realize Monad might be useful: If it makes sense for a "Foo of Foos" (over some type) to be reduced to a Foo. When I realize Applicative might be useful: If it makes sense to apply a "Foo of functions" to a value, or a function taking two or more arguments to two or more Foos, throughout those Foos. -- John Wiegley GPG fingerprint = 4710 CF98 AF9B 327B B80F http://newartisans.com 60E1 46C4 BD1A 7AC1 4BA2