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Template std.algorithm.iteration.map
Implements the homonym function (also known as transform
) present
in many languages of functional flavor. The call map!(fun)(range)
returns a range of which elements are obtained by applying fun(a)
left to right for all elements a
in range
. The original ranges are
not changed. Evaluation is done lazily.
template map(fun...)
;
Contained Functions
Name | Description |
---|---|
map |
Parameters
Name | Description |
---|---|
fun | one or more transformation functions |
See Also
Example
import std .algorithm .comparison : equal;
import std .range : chain;
int[] arr1 = [ 1, 2, 3, 4 ];
int[] arr2 = [ 5, 6 ];
auto squares = map!(a => a * a)(chain(arr1, arr2));
assert(equal(squares, [ 1, 4, 9, 16, 25, 36 ]));
Example
Multiple functions can be passed to map
. In that case, the
element type of map
is a tuple containing one element for each
function.
auto sums = [2, 4, 6, 8];
auto products = [1, 4, 9, 16];
size_t i = 0;
foreach (result; [ 1, 2, 3, 4 ] .map!("a + a", "a * a"))
{
writeln(result[0]); // sums[i]
writeln(result[1]); // products[i]
++i;
}
Example
You may alias map
with some function(s) to a symbol and use
it separately:
import std .algorithm .comparison : equal;
import std .conv : to;
alias stringize = map!(to!string);
assert(equal(stringize([ 1, 2, 3, 4 ]), [ "1", "2", "3", "4" ]));
Authors
License
Copyright © 1999-2022 by the D Language Foundation | Page generated by ddox.