From: Louis J Scoras <louis.j.scoras@...>
Date: 2005-10-20T04:22:48+09:00
Subject: Re: Functional with Ruby

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> But inject *is* functional! It's equivalent to Lisp's accumulate. It
> doesn't modify the list at all or have any side-effects.


Exactly.

Incidentally, the original example isn't really the best way to do this in
Haskell either. I haven't written any Haskell for a while, so some of this
might not be syntactically correct, but you get the idea. Please correct me
if any of this is wrong.

The above would best be expressed something like this (Iike I said, it's
been a while, so the parameter order might be wrong):

foldr + 0 list

foldr does exactly the same thing as inject. It takes a binary function, a
starting value, and a list. The neat thing about Haskell is that the
addition operator--actually any function--is automatically curried.

I'd make the claim here that the use of the higher order function is
actually better functional style than the explicit recursion.

If I recall correctly, many of the list functions in the Hugs standard
library are actually implemented this manner.

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