[Haskell-cafe] (state) monad and CPS

[wren ng thornton]

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