[Haskell-cafe] Requesting Feedback: I Love Haskell, but can't find a place to use it

Doug McIlroy doug at cs.dartmouth.edu
Fri Jun 1 15:22:04 CEST 2012


> > I love Haskell. It is my absolute favorite language.
> > But I have a very hard time finding places where I can actually use it!
> 
> have you considered "your head" as such a place that should be easy to find.

Excellent advice.  Haskell shines unusually brightly on
applications that have an algebraic structure. And laziness
relieves a plethora of sequencing concerns.  I particularly
treasure one experience:

I asked a guru about the complexity of converting regular
expressions to finite-state automata without epsilon transitions
(state transitions that don't produce output).  The best he
knew was O(n^3), which is the cost of removing epsilon transitions
from arbitrary automata.  Then I wrote about a dozen lines of Haskell
to do the job--and running time turned out to be O(n^2). Once
I'd written the code, it became clear how to do it in other
languages, but I never would have found the theorem without
the help of Haskell.  (This without even bringing in the heavy
artillery of higher-order functions and monads.)

Doug McIlroy



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