12 Nov
2009
12 Nov
'09
2:17 a.m.
Nicolas Pouillard wrote:
Excerpts from jean-christophe mincke's message of Tue Nov 10 21:18:34 +0100 2009:
do acc <- get put (acc+1) ...
Since this pattern occurs often 'modify' is a combination of get and put:
do modify (+1) ...
Though the caveat about laziness applies here as well. modify is famously lazy which can lead to space leaks and stack overflows. Better would be to define and use your own strict version: modify' f = get >>= \x -> put $! f x -- Live well, ~wren