[Haskell-cafe] Cal, Clojure, Groovy, Haskell, OCaml, etc.

[Michael Snoyman]

On Wed, Sep 30, 2009 at 6:45 PM, namekuseijin <namekuseijin at gmail.com>wrote:

> On Mon, Sep 28, 2009 at 11:50 PM, Hong Yang <hyangfji at gmail.com> wrote:
> > learn and use. In my humble opinion, Haskell has a lot of libraries, but
> > most of them offer few examples of how to use the modules. In this
> regards,
> > Perl is much much better.
>
> The Perl call is spot on.  Specially because Haskell has been
> incorporating so much syntatic sugar that it's almost looking Perlish
> noise already:
>
> import Data.Array.Diff
> import Data.IArray
>
> update :: (Char -> [Int]) -> DiffArray Int ModP -> Char -> DiffArray Int
> ModP
> update lookup arr c = arr // (map calc . lookup $ c)
>  where
>   calc i = (i, (arr ! i) + (arr ! (i-1)))
>
> solve line sol = (foldl' (update lookup) iArray line) ! snd (bounds iArray)
>  where
>   iArray = listArray (0, length sol) $ 1 : map (const 0) sol
>   lookup c = map (+1) . findIndices (== c) $ sol
>
>
> I've not been following Haskell too much and am completely lost when
> reading code like that.  I understand (+1), : and ! but what the hell
> are . and $ for?
> And that weird monad symbol in the Haskell logo is not even used! >>=
> Not quite the worst example of such line noise much of Haskell
> idiomatic code uses nowadays, though.
>
> Point is:  >>= . $ : ! `` and meaningful whitespace are all nice
> shortcuts, but also hairy confusing...
>
>
I overall agree with the sentiment (I avoid declaring operators at all
costs), but the example is a bad one. $, ., and >>= are all very basic to
Haskell, and should be picked up almost immediately. As far as becoming line
noise like Perl, well, I happen to like Perl :).

Michael
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