[Haskell-cafe] Toy application advice wanted

Ben Lippmeier Ben.Lippmeier at anu.edu.au
Wed May 5 13:46:58 EDT 2004


> I'm evaluating several high-level languages as development 
> vehicles for our next suite of applications. 

> .. just code some really simple problems.
> Like the Sieve of Eratosthenes, in all three languages.
> Or a simple publish/subscribe framework with a "master"
> state holder and many slaves. Or quicksort.  Etc. etc.

I would be careful about using your experience with these toy programs 
as an indication of how suitable functional languages (and lazy ones 
in-particular) are as 'development vehicles' for your applications.

A functional programmer's idea of a 'toy' program tends to be somewhat 
different from a C++/GUI programmers one. Lazy functional languages lend 
themselves nicely to parsing, list processing, search trees and the like 
- but if you're planning to load a wave file, apply a filter and then 
display the result on the screen .. then let's just say that you've got 
an adventure ahead of you, and it's not going to take 2 weeks.

... as far as GUIs are concerned, check out 
http://www.haskell.org/libraries and look at how many seperate GUI 
libraries there are - I counted 16 - then ask what made the developer 
for the 16th one choose to start over.

> Haskell is lazy all the time.  That's awfully nice...I'm not sure if
> there's a performance penalty somewhere, but assuming there isn't, kudos
> to it.

There is.. and its name is 'space leak'.. and the function
mapAccumL :: (acc -> x -> (acc, y)) -> acc -> [x] -> (acc, [y])
is by far the most elegant way of expressing it :)

BTW: I've just dedicated the next 3 years of my life to trying to write 
non-toy programs in lazy functional languages... "adventure" is the 
operative word.. not "can't".


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