Counting occurrences question

[Hal Daume III]

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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