@mut

The @mut keyword reads or writes the mutator attribute for the next block.

Forms

• @mut reads the current mutator function or <> when no mutator is active.
• <@mut> also reads the current mutator.
• <@mut = expr> writes the current attribute frame.
• @mut expr: { ... } applies a mutator to the block that follows immediately.

The assigned value must be a function or <> to clear the mutator.

@mut [?: elem] { [elem]! }: {foo}

foo!

Mutators run once per selected block element and receive the element as a callback parameter.