method flatmap
Documentation for method flatmap
assembled from the following types:
class Any
From Any
(Any) method flatmap
Defined as:
method flatmap(, :)
DEPRECATION NOTICE: This method is deprecated in 6.d and will be removed in 6.e. Use .map
followed by .flat
instead.
Applies map
to every element with the block and Label
used as an argument and flattens out the result using .flat
.
say "aabbccc".comb.Mix.flatmap: "→ " ~ *; # OUTPUT: «(→ b␉2 → c␉3 → a␉2)»
In this case, the elements of the Mix
are itemized to key␉value, and then mapped and flattened. Same result as
say "aabbccc".comb.Mix.map( "→ " ~ * ).flat
Which is why it is deprecated in 6.d and will be eventually eliminated in 6.e.
class List
From List
(List) method flatmap
Defined as:
method flatmap(List: --> Seq)
Like map
iterates over the elements of the invocant list, feeding each element in turn to the code reference, and assembling the return values from these invocations in a result list.
The use of flatmap
is strongly discouraged. Instead of .flatmap( )
, please use .map( ).flat
as it is clear when the .flat
is called and is not confusing like .flatmap
.
Unlike map
it flattens non-itemized lists and arrays, so
## flatmapmy = ('first1', ('second2', ('third3', 'third4'), 'second5'), 'first6');say .flatmap().perl;# OUTPUT «("first1", "second5", "third3", "third4", "second2", "first6").Seq»## mapsay .map().perl;# OUTPUT «("first1 was a Str", "second2 third3 third4 second5 was a List", "first6 was a Str").Seq»## .map .flat has the same output as .flatmapsay .map().flat.perl# OUTPUT «("first1", "second5", "third3", "third4", "second2", "first6").Seq»