- | ps wp ^"/" ws e
-psx ::= psy ^"?=>" e /ws
- | psy ^"!=>" e /ws
- > psy
-sequence ::= quoted => "qprod"
- > psx
- | psx ^"=>" (word|quoted) /ws
-
-ec ::= [~\-\]\\\~]
+ | ps !wp ^"/" !ws e
+psx ::= psy => "psy"
+// | e "<-" psy /ws => "psyl"
+ | psy "->" e /ws => "psyr"
+// | e "<-" psy "->" e /ws => "psylr"
+Sequence ::= Quoted => "qprod"
+ > psx => "psx"
+ | psx "=>" ^"[]" /ws
+ | psx ^"=>" ("()"|word|Quoted) /ws
+
+ec ::= ~[\-\]\\]