# Counting occurrences question

**Hal Daume III
**
hdaume@ISI.EDU

*Wed, 5 Jun 2002 11:08:42 -0700 (PDT)*

Probably is a homework question, so HINT:
you can do it using 2 and only 2 prelude functions and no additional
function definitions of your own.
--
Hal Daume III
"Computer science is no more about computers | hdaume@isi.edu
than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume
On Wed, 5 Jun 2002, Andy Fugard wrote:
>* >===== Original Message From "xoo" <ixoo21@hotmail.com> =====
*>* >hi.. i was just wondering if some body could give a simple equation for the
*>* following situation.other than recursion plz..
*>* >
*>* >occurrences :: Eq a => a -> [a] -> [a]
*>* >--occurrences xs ys returns the number of times that xs occurs in ys
*>*
*>*
*>* You may find it easier if you make
*>*
*>* occurrences :: Eq a => a -> [a] -> Integer
*>*
*>* since it would seem it is to return a number, and not another list!
*>*
*>* Also I would guess the function will have a form something like
*>*
*>* occurrences x xs = foldr (countOp x) 0 xs
*>* where countOp :: Eq a => a -> a -> Integer -> Integer
*>* ...
*>*
*>* I'm not sure if I should go any further, in case this is a homework
*>* question...
*>*
*>* Andy
*>*
*>* --
*>* [ Andy Fugard ]
*>* [ +44 (0)7901 603075 ]
*>*
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