Statements

Every statement is an expression, optionally followed by a modifier, and terminated by a semicolon. The semicolon may be omitted if the statement is the final one in a BLOCK.

Execution of expressions can depend on other expressions using one of the modifiers if, unless, while or until, for example:

EXPR1 if EXPR2 ;
EXPR1 until EXPR2 ;

The logical operators ||, && or ?: also allow conditional execution:

EXPR1 || EXPR2 ;
EXPR1 ? EXPR2 : EXPR3 ;

Statements can be combined to form a BLOCK when enclosed in {}. Blocks may be used to control flow:

if (EXPR) BLOCK [ [ elsif (EXPR) BLOCK ... ] else BLOCK ]
unless (EXPR) BLOCK [ else BLOCK ]
[ LABEL: ] while (EXPR) BLOCK [ continue BLOCK ]
[ LABEL: ] until (EXPR) BLOCK [ continue BLOCK ]
[ LABEL: ] for (EXPR; EXPR; EXPR) BLOCK
[ LABEL: ] foreach VAR† (LIST) BLOCK
[ LABEL: ] BLOCK [ continue BLOCK ]

Program flow can be controlled with:

goto LABEL Continue execution at the specified label. last [ LABEL ] Immediately exits the loop in question. Skips continue block. next [ LABEL ] Starts the next iteration of the loop. redo [ LABEL ]   Restarts the loop block without evaluating the conditional again.

Special forms are:

do BLOCK while EXPR ;
do BLOCK until EXPR ;

which are guaranteed to perform BLOCK once before testing EXPR, and

do BLOCK

which effectively turns BLOCK into an expression.