On 16/09/05, Mark Carter
This is not a troll, honest, so please bear with me ...
I'm a C/C++/VBA programmer (although the former 2 are several years old for me), with a sprinkling of Python. Needless to say, I was looking to see if there were any better ways of doing things. I've given things like Ruby and Scheme a bit of peck, and failed to get particularly enthusiastic about them. Two very interesting choices, though, appear to be Lisp and Haskell. It struck me that Lisp was, perhaps, the Ultimate Programming Language, the One True Language to rule them all; except that I always kept abandoning it for one reason or another (fiddly installation, lack of libraries, compatability problems, cost, possible license issues, etc.). My current foray in Haskell seems encouraging. wxHaskell installed a breeze, and seems quite usable (even though I'm a raw n00b to the language, and admittedly haven't grokked the semantics, and all this cid:part1.01000702.09000407@yahoo.co.uk IO a -> IO () business). On the one hand, it seems kinda academic, but on the other, it looks like it wants to be practical, too.
Bearing this in mind, and hoping you can see where I'm coming from, I think my question is: shouldn't you guys be using Lisp?
Well, there are a number of reasons which people might have for choosing one over the other. I think you'll find that many Haskellites are familiar with one or more variants of lisp and ML. I'll try to provide some reasons that I find Haskell a fun and pleasant programming language to write things in. (Actually, a fair bit moreso than any other language that I've come across.) One is that Haskell is lazily evaluated, and I really find that a lot more natural than strict evaluation. It opens up a lot of ways of writing code and thinking about code which would otherwise be unavailable. In a strict language, you have to jump through some hoops whenever infinite or very large amounts of data come along. You tend to have to use different methods than you would for small data structures in order to compute only small parts at any one time, and throw away the parts that you're done with explicitly. In a lazy language, a list is a list, and a tree is a tree, and the same functions and techniques apply to them. Even if your data are moderately sized, there are often times that the easiest algorithm to write involves a large intermediate data structure, though you'll only look at it one piece at a time, and maybe won't look at all of it. With lazy evaluation, you're not penalized for doing things that way. Of course, there are times when you really want strict evaluation, and Haskell has ways to provide that. I find that they are relatively rare. Another reason is that it is statically type checked. The type system in Haskell is quite expressive, and I find that it helps to catch bugs to an incredible extent, and also to structure the way that you think about code. With algebraic datatypes and the collection of standard data structures in the libraries, you also don't lose very much flexibility over dynamically typed structures. The type system also helps you jump into unfamiliar code. People tend to write Haskell code which uses types in order to distinguish and catch those things which are obviously incorrect. When trying to sort out how a piece of code works, or how to extend it, there is a somewhat more restricted way that things could be fitting together at any one point, so it's easier to figure out what's going on, and pin down the places where you might want to extend things. You can often go quite a long way in understanding code just by looking at the types. I also find that just through using Haskell, and being around the Haskell community, I expose myself to a lot of exciting computer science research. I'm still quite impressed that category theory has found practical applications so quickly. :) Haskell people in general seem to be experimenting with new kinds of abstractions and seeing how far they can be taken in being put to practical use. Haskell itself seems to be developing in directions which serve this experimentation, and at the same time is becoming more and more practical. Anyway, these are just some highlights of what I find fun about it, and of course none of this is meant in any way to detract from all the other great languages out there. Exploring different programming languages is a lot of fun and can really expand the way that you think about code. I encourage you to do so as much as possible. - Cale