[Haskell-cafe] First time haskell - parse error!

[Sebastian Fischer]

On Mar 10, 2010, at 12:21 PM, Ketil Malde wrote:

> Introducing names means that I need to keep the temporary  
> definitions in my
> head, and I think "takeWhile (<10000)" is as clear as it can get.  And
> while a name can be misleading (belowLimit is a boolean, no?) or flat
> out wrong, the definition has its semantics¹.

I agree that composition chains are acceptable (and preferable) if  
they are clear. And I won't argue about wether the example from  
LYAHFGG is sufficiently clear in pointfree style (because I'm biased,  
to me it is certainly clear).

I do not agree that introducing names locally for compositions is  
*always* a bad idea, even if used only once. (Choosing names that are  
"misleading or flat out wrong" is of course always a bad idea.)

> Named values are just like comments

While you wanted to degrade named values by this statement I think it  
can serve as justification. A sensible comment for the example program  
might be

     -- computes the sum of all odd squares below a certain limit

With the names in the rewritten example this comment is no longer  
necessary. I think only an average Haskell programmer understands the  
original pointfree program as quickly as this comment.

Good names can help making comments less important.

Sebastian

-- 
Underestimating the novelty of the future is a time-honored tradition.
(D.G.)