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Re^3: regex and "Functional Programming"

by FoxtrotUniform (Prior)
on Oct 23, 2004 at 21:16 UTC ( #401887=note: print w/ replies, xml ) Need Help??

in reply to Re^2: regex and "Functional Programming"
in thread regex and "Functional Programming"

There's a whole lot of iterating going on in functional languages; it's just going to tend to look like perl map or foreach loops and not like a while or C-style for loop.

Heh. I can't speak for all functional languages, but the map function in Haskell is defined recursively in the Haskell Standard Prelude. So is iterate (which really means "repeat-compose"), as well as the folds. Hell, even the "iterative" sequenced monad operations are defined recursively. Mostly, this follows from the recursive definition of lists: a list is either an empty list, or a datum consed onto a list.

There's probably some iteration going on in even the most standards-compilant Haskell implementation, but as far as I can tell none of it happens at the language level. Feel free to correct me, though, if you find any in the Prelude; I don't know it as well as I ought.

Of course, the first example in my copy of ANSI Common Lisp isn't very "functional" at all:

(defun sum (n) (let ((s 0)) (dotimes (i n s) (incf s i))))

Yours in pedantry,
F o x t r o t U n i f o r m

"Lines of code don't matter as long as I'm not writing them." -- merlyn

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