Conditionals

You can write if-then-else statements that evaluate to values as in

if 1 > 0 then 1 else 0 end;

which evaluates to 1. The ``then'' and ``else'' parts of the statement must have the same types and the ``if'' part must be a boolean expression. Thus, the following produce type errors:

if 1 then 1 else 0 end;
if 1 < 0 then 1 else "oops" end;

It is important to remember that, if-statements evaluate to values (kind of like the a ? b : c syntax in C). So for example, the following is perfectly legal:

"ccl is " <> ( if true 
                 then "strange but beautiful" 
                 else "just strange" 
               end );

which you can probably evaluate in your head.