map()

map([<object>/]<attribute>, <list>[, <delim>[, <osep>[, <arg1>, ... , <argN>]]])

This function works much like ITER(). The given <attribute> is evaluated once for each element of <list>, and the results of the evaluations are returned. For each evaluation, the current list element is passed to the attribute as %0, and its position in the list as %1. Elements of <list> are separated by <delim>, or a space if none is given, and the results are returned separated by <osep>, if given, or the delimiter otherwise. An empty <osep> puts nothing between them.

It is like this, but slightly faster:

iter(<list>, ulambda(<object>/<attribute>, %i0, inum(0)), <delim>, <osep>)

map arguments: passing extra arguments to the attribute
map examples: doubling a list with and without a delimiter

Extra arguments

Any arguments after <osep> are passed to the attribute as %1, %2 and so on, in place of the position. Passing them comes from RhostMUSH, and so does reading an empty <osep> before them as a space. With the rhost_map_args option on, %1 is empty when there are none, as on RhostMUSH, rather than the position (see compatibility config).

> &show_args me=<%0:%1:%2>
> think map(show_args, a b,,, x, y)
<a:x:y> <b:x:y>

Examples

> &times_two me=mul(%0,2)
> say map(times_two, 5 4 3 2 1)
You say, "10 8 6 4 2"
> say map(times_two,1;2;3;4;5,;)
You say, "2;4;6;8;10"

::: seealso