intersperse package:streamly

Insert a pure value between successive elements of a stream.

>>> Stream.toList $ Stream.intersperse ',' $ Stream.fromList "hello"
"h,e,l,l,o"

Insert an effect and its output before consuming an element of a stream except the first one.

>>> Stream.toList $ Stream.trace putChar $ Stream.intersperseM (putChar '.' >> return ',') $ Stream.fromList "hello"
h.,e.,l.,l.,o"h,e,l,l,o"

Be careful about the order of effects. In the above example we used trace after the intersperse, if we use it before the intersperse the output would be he.l.l.o."h,e,l,l,o".

>>> Stream.toList $ Stream.intersperseM (putChar '.' >> return ',') $ Stream.trace putChar $ Stream.fromList "hello"
he.l.l.o."h,e,l,l,o"

Insert a side effect before consuming an element of a stream.

>>> Stream.toList $ Stream.trace putChar $ Stream.intersperseMPrefix_ (putChar '.' >> return ',') $ Stream.fromList "hello"
.h.e.l.l.o"hello"

Same as trace_ but may be concurrent. Concurrent Pre-release

Insert an effect and its output after consuming an element of a stream.

>>> Stream.toList $ Stream.trace putChar $ intersperseMSuffix (putChar '.' >> return ',') $ Stream.fromList "hello"
h.,e.,l.,l.,o.,"h,e,l,l,o,"

Pre-release

Like intersperseMSuffix but intersperses an effectful action into the input stream after every n elements and after the last element.

>>> Stream.toList $ Stream.intersperseMSuffixWith 2 (return ',') $ Stream.fromList "hello"
"he,ll,o,"

Pre-release

Insert a side effect after consuming an element of a stream.

>>> Stream.mapM_ putChar $ Stream.intersperseMSuffix_ (threadDelay 1000000) $ Stream.fromList "hello"
hello

Pre-release

Intersperse a monadic action into the input stream after every n elements.

> Stream.toList $ Stream.intersperseMWith 2 (return ',') $ Stream.fromList "hello"
"he,ll,o"

Unimplemented

Insert a side effect before consuming an element of a stream except the first one.

>>> Stream.drain $ Stream.trace putChar $ Stream.intersperseM_ (putChar '.') $ Stream.fromList "hello"
h.e.l.l.o

Pre-release