# mapcat
Apply a function to each element of a collection and concatenate the results (flat map).
## Syntax
[mapcat $coll $f] [mapcat $f]
## Parameters
- `$coll` — Collection to transform (2-arg form).
- `$f` — Function returning a collection for each element.
## Examples
[mapcat @{ 1 2 3 } { @{$it $it} }] # @{ 1 1 2 2 3 3 }
[mapcat @{ "ab" "cd" } { chars $it }] # @{ "a" "b" "c" "d" }
## Returns
2-arg: a list (concatenated). 1-arg: a transducer.
## See Also
`map`, `comp`, `transduce`, `collect`