27 May
2012
27 May
'12
7:33 p.m.
Hi Chris, On 05/27/2012 10:04 AM, Chris Wong wrote:
I just came up with a way of executing multiple folds in a single pass. In short, we can write code like this:
average = foldLeft $ (/)<$> sumF<*> lengthF
and it will only traverse the input list once.
The code is at: https://gist.github.com/2802644
My question is: has anyone done this already? If not, I might release this on Hackage -- it seems quite useful.
This is (a special case of) the main point in the design of iteratees. See e.g. the definition of the 'Iteratee' type in the enumeratee library. - Looks pretty much like your 'Fold' type with an additional state (done or not yet done). Also, the pipe package seems to provide something similar. -- Steffen