Executes a body if a test expression is true, and does nothing if the test is false. This macro behaves identically to Dylan’s standard if statement macro, except that there is no alternative flow of execution when the test is false.
when (x < 0)
~ x;
end;
when ( (test) )
(consequent)
end when
| test | An expression. |
| consequent | A body; a series of semicolon-separated expressions. |