This article is from the FAQ, by with numerous contributions by others.
Often the following If statement is used:
do (if b//TRUE then ... else ... if);
The current version of the compiler supports an extension to the BETA
language called Simple If. This extension means, that the case-selector //
may be omitted, if the evaluation on the left hand side exits a boolean.
That is, the above may be written
do (if b then ... else ... if);
Like in the general if-statement, the else part if optional.