Re: Haskell, anyone?

[Mark Carroll <mtbc@bcs.org>]

On 17 Nov 2015, Dmitry A. Kazakov wrote:

> On Mon, 16 Nov 2015 15:23:16 -0800, Paul Rubin wrote:
>
>> Hadrien Grasland <hadrien.grasland@gmail.com> writes:
>
>>> "The compiler and the user are both clever enough". 
>> 
>> It's true that there are FP idioms you have to get used to if you're
>> coming from imperative programming.
>
> Because declarative programming is non-algorithmic and no programming at
> all, if taken seriously. It is like the idea of stateless programming, just
> a fiction.

Chris Okasaki's "Purely Functional Data Structures" is a great
introduction to the basics of what one can do with algorithms when one
takes declarative programming seriously, regardless of if one deems it
"non-algorithmic and no programming at all". I do generally find it
possible to translate algorithms from books like CLR(S) -- longest
common subsequence or directed graph maximum flow or whatever -- to
being purely declarative, it just means that I have to step back and
really understand the idea and approach of the algorithm, rather than
just mechanically translating their for loops and arrays and whatever
into the appropriate syntax. For instance, with Haskell the elements of
an array of an imperative algorithm may become return values from some
recursive lazily evaluated function. (It is still possible to use an
imperative approach when it fits best, for instance I often did when
translating my simple sysadmin Perl 5 scripts to Haskell.) But I fear
we're drifting off-topic so I'll again return to lurking here and look
out for any queries in comp.lang.haskell.

-- Mark