[Haskell-beginners] Question about recursion

[Brent Yorgey]

On Tue, Nov 09, 2010 at 06:14:49PM +0200, Nadav Chernin wrote:
> 
> There is problem that in each step of recursion this function sort list
> of indexes ( in last line)
> 
> How can I write this code that sorting will be executed only once (in
> first step)?

Just write a helper function that does all the actual work, and have
delIndexes pass it a sorted index list as input:

  delIndexes inds l = delIndexes' (sort ind) l
    where delIndexes' ...

-Brent