what is the purpose of arrows?

Posted by Simon on Programmers See other posts from Programmers or by Simon
Published on 2011-10-17T11:40:20Z Indexed on 2012/10/09 15:54 UTC
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functional-programming

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haskell

I am learning functionnal programming with Haskell, and I try to grab concepts by first understanding why do I need them.

I would like to know the goal of arrows in functional programming languages. What problem do they solve? I checked http://en.wikibooks.org/wiki/Haskell/Understanding_arrows and http://www.cse.chalmers.se/~rjmh/afp-arrows.pdf. All I understand is that they are used to describe graphs for computations, and that they allow easier point free style coding.

The article assume that point free style is generally easier to understand and to write. This seems quite subjective to me. In another article (http://en.wikibooks.org/wiki/Haskell/StephensArrowTutorial#Hangman:_Main_program), a hangman game is implemented, but I cannot see how arrows makes this implementation natural.

I could find a lot of papers describing the concept, but nothing about the motivation.

What I am missing?

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