Haskell [Was: Re: A few comments about D]

[Jonathan M Davis]

On Wednesday, August 24, 2011 04:22 bearophile wrote:
> Caligo:
> > Haskell is one of the most beautiful languages. I wish I had discovered
> > it sooner.
> 
> I am now able to write small Haskell programs. It has some features and
> parts that I like significantly (and I'd like some of them in D too!), but
> so far I am not appreciating it much on the whole. It feels almost like a
> "puzzle language", as Forth (almost, but not really). Those operators are
> not easy to find in the documentation, the purpose of all those little
> functions is not easy to remember, and its obsession with purity sometimes
> turns easy things into very complex things (I like purity and
> immutability, but not much inside functions, so I prefer D). It's good for
> some kinds of tasks (Euler Puzzles, certain math tasks, certain
> experiments about types), acceptable for other tasks (some generic
> algorithms, some string processing, etc), and bad for many other purposes,
> so it doesn't feel like a general purpose language. I am sometimes able to
> write very short programs with it, but often they are slow. It's not easy
> for me to tell how much efficient a program will be, onc! e compiled with
> GHC. Keep in mind that I am a newbie of Haskell, so don't take my comments
> too much seriously :-)

I like Haskell and have used it a fair bit, but I don't use it a lot these 
days. I think that every serious programmer should study and learn at least 
one functional language. Learning to think functionally can have be very 
helpful even in imperative programming and will make you a better programmer. 
And on top of the kind of stuff that it normally helps with (like 
understanding recursion), in D it helps when dealing with ranges, since ranges 
can be processed like slists a lot of the time.

However, as much as I like Haskell, I find it very hard to work with on 
anything large, and even smaller stuff can be difficult. It just requires too 
much brain-bending to figure out how to do something purely functionally for 
it to be easy, and Haskell's laziness makes debugging it very difficult.

So, I definitely recommend learning a functional lanugage (and Haskell is a 
good one), but I wouldn't program in it as my primary language. The main 
reason that I've used it as much as I have is that it has a fantastic parsing 
library (Parsec). And actually, I've been working on trying to port it to D, 
though it'll probably be a while before I finish it, and the lack of laziness 
could actually be a performance impediment in this case, since you risk having 
to copy the parsing state too often. Hopefully I can get that sorted out 
though. I still have a ways to go with it regardless.

- Jonathan M Davis