[Haskell-cafe] Point-free style (Was: Things to avoid)
jmaessen at alum.mit.edu
Thu Feb 10 09:23:11 EST 2005
On Feb 10, 2005, at 6:50 AM, Henning Thielemann wrote:
> On Thu, 10 Feb 2005, [ISO-8859-1] Thomas Jäger wrote:
>> Altogether, the spirit of the page seems to be "use as little
>> syntactic sugar as possible" which maybe appropriate if it is aimed at
>> newbies, who often overuse syntactic sugar (do-notation).
> This overuse is what I observed and what I like to reduce. There are
> people advocating Haskell just because of the sugar, which let
> people fail to see what's essential for Haskell. When someone says to
> that there is a new language which I should know of because it supports
> definition of infix operators and list comprehension, I shake my head
> wonder why he don't simply stick to Perl, Python, C++ or whatever.
If you're trying to avoid obscurity, why advocate point-free style?
I ask this question to be deliberately provocative; I'm not trying to
single you out in particular. So, to everybody: What's so great about
Is it really clear or obvious what
> map . (+)
means? Contrast this with
> \n -> map (+n)
> \n xs -> map (+n) xs
I submit that, while it is possible to develop a reading knowledge of
point-free style, non-trivial use of point-free
computations---compositions of functions with arity greater than 1, as
above, compositions of sections of composition or application, arrow
notation without the sugar, and so forth---will always be more
difficult to read and understand than the direct version. I submit
that this is true even if one is familiar with point-free programming
and skilled in its use.
Even something as simple as eta-reduction (as in the second and third
functions above) can seriously obscure the meaning of program code by
concealing the natural arity of a function.
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