Make Prelude's map = fmap

Andrew Butterfield Andrew.Butterfield at
Fri Jun 21 11:59:03 CEST 2013

On 21 Jun 2013, at 10:51, Nikita Volkov wrote:

> Since there's been so many suggestions concerning radically changing the Prelude recently, I'd like to start a poll on a subject.
> I know that "map" is limited to lists for the beginners, but then we're already making a lot of unbeginnerish changes to Prelude. Also it's not a monad transformer, but just a functor - how can a person learn Haskell without understanding what a Functor is?

!!!! No one needs to know what a functor is in order to learn Haskell.
No one needs to know any category theory ideas to learn Haskell.

Haskell is a very good vehicle to introduce such category-theoretic concepts,
and as someone learns Haskell, learning about Haskell classes(*) such as Functor,
etc, is very important and useful. 

My main reason for this sudden and abrupt response is that I would be worried if
any Prelude re-design was predicated on the idea that Haskell beginners need to understand Functors
 - they don't, but hopefully they will learn...

(*) as distinct from learning about the category theoretic notion of functor.

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Andrew Butterfield     Tel: +353-1-896-2517     Fax: +353-1-677-2204
Lero at TCD, Head of Foundations & Methods Research Group
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School of Computer Science and Statistics,
Room G.39, O'Reilly Institute, Trinity College, University of Dublin

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