mapM_ -package:conduit

Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. mapM_ is just like traverse_, but specialised to monadic actions.

Perform a computation on each Word8 in a stream. Since 1.0.10

Consume all values using a monadic function

Converts an effectful function to a fold. Specialized version of sink.

Maps a side effect over an InputStream. mapM_ f s produces a new input stream that passes all output from s through the side-effecting IO action f. Example:

ghci> Streams.fromList [1,2,3] >>=
Streams.mapM_ (putStrLn . show . (*2)) >>=
Streams.toList
2
4
6
[1,2,3]

A side-effecting map over the key-value records of a hash table. O(n).

See the documentation for this function in mapM_.

See the documentation for this function in mapM_.

See the documentation for this function in mapM_.

See the documentation for this function in Data.HashTable.Class#v:mapM_.

Reduce a stream to its return value with a monadic action.

>>> S.mapM_ Prelude.print $ each [1..3]
1
2
3

>>> rest <- S.mapM_ Prelude.print $ S.splitAt 3 $ each [1..10]
1
2
3

>>> S.sum rest
49 :> ()

Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. As of base 4.8.0.0, mapM_ is just traverse_, specialized to Monad.

O(n) Apply the monadic action to all elements of a vector and ignore the results

O(n) Apply the monadic action to all elements of a vector and ignore the results

O(n) Apply the monadic action to all elements of a vector and ignore the results

O(n) Apply the monadic action to all elements of a vector and ignore the results

Synonym for omapM_

A map in monad space, discarding results.

mapM_ = Stream.drain . Stream.mapM

Apply a monadic action to each element of the stream and discard the output of the action. This is not really a pure transformation operation but a transformation followed by fold.

A mapM_ equivalent.

Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. mapM_ = traverse_

Like mapM_, but applying the function to the individual list items in parallel.

Constrained to Container version of mapM_.

>>> mapM_ print [True, False]
True
False