A function containing one statement which returns a result:
foo:{x+y}
A function containing many statements which returns a result:
foo:{
a:first x;
b:last x;
a+b}
A multi-line function which does not return a result should always end with an isolated brace.
foo:{
Sum::x+y;
Prod::x*y;
}
A function with one line which does not return a result can be written on a single line, using a semicolon.
foo:{Sum::x+y;}
but consistent use of the isolated brace to mean no result suggests we write:
foo:{
Sum::x+y;
}