Hi,
The pipes-group and streaming libraries both give you functions like
"group", "groupBy" and "chunksOf" that let you segment a stream while
preserving streaming. I was thinking of implementing these two additional
functions:
delimit :: (x -> a -> (x,NonEmpty [b]))
-> x
-> (x -> NonEmpty [b])
-> Stream (Of a) m r
-> Stream (Stream (Of b) m) m r
delimitM :: (x -> a -> Stream (Of b) m (Stream (Stream (Of b) m) m x))
-> m x
-> (x -> Stream (Of b) m (Stream (Stream (Of b) m) m ()))
-> Stream (Of a) m r
-> Stream (Stream (Of b) m) m r
For "delimit", the idea is that every step produces a NonEmpty list of
lists along with the new internal state. The list at the head would consist
of elements belonging to the "current open group". If there are more lists
afterwards, they represent new groups which have been detected in the
stream. For streams comprising one single continuous group, the NonEmptys
would *always* contain just one list.
"delimitM" is the monadic version, although here the types start getting
quite scary.
What do you think? Would "delimit" make sense, or at this level of
complexity it would be better to build the splitting function by
single-stepping the source stream?
(Extra semi-related question: could the FreeT trick used in pipes-group
also be applied to Sources from the conduit library?)
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