That's presumably what it means: the proposal was a syntax change of metalua's pattern matching, and the original stuff is "<pattern> -> <block>", which can be protected with a guard _expression_ (which can prevent the pattern from matching if it returns false): "<pattern> if <guard-_expression_> -> <block".
Clearly this forces a sequential evaluation, unless onw starts to make the compiler really complex. But the intended use case for pattern matching isn't as a simple switch/case, although it happens to cover that case as well.
