Re: [Haskell-beginners] Good style on "." and "$" pipeline?

On Wed, Aug 22, 2012 at 3:41 AM, Felipe Almeida Lessa wrote:

On Tue, Aug 21, 2012 at 10:34 PM, koomi wrote:

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On 21.08.2012 22:43, Brent Yorgey wrote:

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Having more than one $, like (f1 $ f2 $ fn $ arg), is frowned upon. Care to explain why this is considered bad? I don't see anything wrong with this.

It's just a matter of taste. Personally, I usually prefer using many ($)s rather than combining (.)s and ($)s on the same "phrase".

It is a bit more than a matter of taste : the (.)s then one ($) style allows easier and clearer refactoring because each part of the function pipeline can be just copy pasted somewhere else, for instance you can get from :

bigFunc = f1 . f2 . f3 . f4 $ arg

to

bigFunc = f1 . meaningfulFunc . f4 $ arg

meaningfulFunc = f2 . f3

without rewriting a bit of your pipeline to change $ to . or add a point to meaningfulFunc (note that I ignore the monomorphism restriction here, I would give those function signatures anyway since they're top-level). I find this style makes it easier to reason about in a purely "pipelinesque" way (focused on functions and their combinations). -- Jedaï