Haskell 2010 Announced 173
paltemalte writes "Simon Marlow has posted an announcement of Haskell 2010, a new revision of the Haskell purely functional programming language. Good news for everyone interested in SMP and concurrency programming."
Re:Is it just me ? (Score:4, Informative)
I'm not sure what you mean by "recursive style", but the biggest commercial users of functional programming languages tend to be companies behind high-traffic websites that need to handle a lot of concurrent requests. Facebook developed their real-time chat application in Erlang, for instance, and Twitter uses Scala to handle its message queue.
Re:Is it just me ? (Score:4, Informative)
> I'm not sure what you mean by "recursive style",
Look at Quicksort in Haskell :
qsort [] = []
qsort (x:xs) = qsort (filter (= x) xs)
This is what I mean, no loops, recursion. I used Prolog and ML to solve logic problems and it is pretty handy. Prolog is especially suited for solving logic problems ( "logic programming" ).
Re:Is it just me ? (Score:4, Informative)
Re:Is it just me ? (Score:5, Informative)
Re:Is it just me ? (Score:5, Informative)
Erlang and Scala are both languages designed to support programming in a functional style, and both are "recursive style" languages in that they optimize tail calls generally (Erlang) or at least in the most important case of self-recursive calls (Scala) and thus make tail-recursive (or, in Erlang's case, more general tail calling with unlimited depth) programming styles efficient.
Neither is a pure functional programming language, true.
Re:Is it just me ? (Score:5, Informative)
I would add a couple other "must have" features in functional languages:
* The ability to pass a function as an argument to another function (i.e. higher order functions, like qsort in the C standard library).
* Support for a points-free programming style in which things can be passed from one function to another without naming them.
Some other features that perhaps aren't technically required but make functional programming a lot easier:
* Closures, local function definitions, garbage collection, partial evaluation of function.
Re:Is it just me ? (Score:3, Informative)
You misunderstand what he means by "getting past" Amdahl's Law. That wouldn't involve somehow changing the fact that only speeding up part of a program can only do so much to speed the whole program- it'd involve radically changing the proportion of various algorithms which can be parallelized. For instance, if somebody were to come up with a constructive proof that P [wikipedia.org]=NC [wikipedia.org] that'd certainly do the trick (though most people's guess is that that's false).
hGetContents is only *technically* typesafe (Score:3, Informative)
Actually hGetContents cheats by using unsafeInterleaveIO. It's a cool hack, but lazy IO is an inherently risk business. For instance, if your program later wrote back changes to your scene file, the result is undefined. There's no guarantee of when the program is done reading the file. If you keep this in mind it's no problem, but if all IO worked this way you'd go insane. (Also consider the problem of error handling if there's a disk error.)
Re:Is it just me ? (Score:3, Informative)
I guess I was thinking more of the fairly universal concept that you can use the result of one function as an argument to another without giving it a name. For instance:
result = f(g(x))
instead of
foo = g(x); result = f(foo)
Haskell applies a points-free style in more cases than we're used to seeing in other languages, which is sometimes useful but I agree it is just as often an annoyance to those who are trying to understand someone else's code. I was thinking of a rather looser definition of points-free, which is present to some degree in all the programming languages I'm familiar with.