Statements and Control Flow

This page defines executable statements. See the shorter Statements guide.

Blocks

The canonical form begins a block with : and closes it with a matching end... keyword such as endif, endwhile, endfor, endfunc, or endtry. Supported statements may alternatively use braces. One block must use one closing style consistently.

Declaration and Assignment Statements

Variable and constant declarations are statements. = assigns; modify-assign forms such as +=, -=, and the typed operator variants update an existing assignable destination. Assignment is not an expression.

A property setter can be the destination of plain or modify assignment. The getter must also exist for a modify assignment because the current value is read before the result is written.

Conditional Statements

if and elif conditions must be bool. At most one branch executes.

if ready:
    Run()
elif retry:
    TryAgain()
else:
    Stop()
endif

While

while condition evaluates a Boolean condition before each iteration. continue starts the next iteration and break exits the nearest loop.

Numeric For Loops

The implemented forms are:

for i : int = first to last step amount:
endfor

for i : int = first downto last step amount:
endfor

for i : int = first count iterations step amount:
endfor

for i : int = first downcount iterations step amount:
endfor

for i : int = first while condition step amount:
endfor

to and downto use inclusive endpoints. count and downcount execute the requested number of iterations. Their explicit step magnitude must be positive; the direction comes from the loop form. The while form applies its step after the body and permits an expression appropriate to its condition.

The initial value, limit/count, and step are evaluated according to the loop's entry semantics rather than being arbitrary assignment expressions in the body.

Return

return leaves the current function. A value-returning function may use return expression or assign its built-in result variable before falling through or returning.

Exceptions

raise expression raises an exception object. try may have typed except clauses and a finally clause.

try:
    ReadData()
except EFile as error:
    error.PrintMessage()
except Exception:
    raise
finally:
    CloseData()
endtry

Exception clauses are checked in source order. A clause matches its declared object type and derived types. A bare raise inside a handler re-raises the active exception.

finally executes whenever control leaves the protected statement, including normal completion, propagation, return, break, and continue. If code in finally raises another exception, that new exception becomes the active failure.

During unwinding, initialized owned locals are cleaned up in reverse lifetime order. A top-level unhandled exception prints its message and captured backtrace through the hosted runtime before terminating.

Method-Local Use

An object method may use the restricted local forms use . and an available module namespace to opt selected module-scope values into method lookup. This does not create a general function-local import facility.