[Haskell-cafe] Comments from OCaml Hacker Brian Hurt

Lennart Augustsson lennart at augustsson.net
Sat Jan 17 10:33:07 EST 2009

Thinking that Functor allows you to apply a function to all elements
in a collection is a good intuitive understanding.  But fmap also
allows applying a function on "elements" of things that can't really
be called collections, e.g., the continuation monad.

  -- Lennart

On Sat, Jan 17, 2009 at 11:17 AM, Andrew Coppin
<andrewcoppin at btinternet.com> wrote:
> Cory Knapp wrote:
>> Actually, that was part of my point: When I mention Haskell to people, and
>> when I start describing it, they're generally frightened enough by the focus
>> on pure code and lazy evaluation-- add to this the inherently abstract
>> nature, and we can name typeclasses "cuddlyKitten", and the language is
>> still going to scare J. R. Programmer. By "inherently mathematical nature",
>> I didn't mean names like "monoid" and "functor", I meant *concepts* like
>> monoid and functor. Not that either of them are actually terribly difficult;
>> the problem is that they are terribly abstract. That draws a lot of people
>> (especially mathematicians), but most people who aren' drawn by that are
>> hugely put off-- whatever the name is. So, I guess my point is that the name
>> is irrelevant: the language is going to intimidate a lot of people who are
>> intimidated by the vocabulary.
> Oh, I don't know. I have no idea what the mathematical definition of
> "functor" is, but as far as I can tell, the Haskell typeclass merely allows
> you to apply a function simultaneously to all elements of a collection.
> That's pretty concrete - and trivial. If it weren't for the seemingly
> cryptic name, nobody would think twice about it. (Not sure exactly what
> you'd call it though...)
> A monoid is a rather more vague concept. (And I'm still not really sure why
> it's useful on its own. Maybe I just haven't had need of it yet?)
> I think, as somebody suggested about "monad", the name does tend to inspire
> a feeling of "hey, this must be really complicated" so that even after
> you've understood it, you end up wondering whether there's still something
> more to it than that.
> But yes, some people are definitely put off by the whole "abstraction of
> abstractions of abstraction" thing. I think we probably just need some more
> concrete examples to weight it down and make it seem like something
> applicable to the real world.
> (Thus far, I have convinced exactly *one* person to start learning Haskell.
> This person being something of a maths nerd, their main complaint was not
> about naming or abstraction, but about the "implicitness" of the language,
> and the extreme difficulty of visually parsing it. Perhaps not surprising
> comming from a professional C++ programmer...)
>> At the same time, I think everyone is arguing *for* better documentation.
>> And you're probably right: better documentation will bring the abstract
>> nonsense down to earth somewhat.
> Amen!
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