dmajda/pegjs — Issue #66: Make &... and !... not return any value
Author: dmajda
Created: 2012-02-03 07:42:33+00:00
State: open
Labels: Feature

In sequences, returning a value from predicates only confuses users. For example, `start = "a" &. "b"` returns `["a", "", "b"]`, on input "ab", but users expect `["a", "b"]`.

This means predicates won’t be allowed outside of sequences or in one-element sequences because such expressions would have undefined value.