s ::= ws grammar ws => "gram"
-ws !::= w**
+ws !::= w**
+wp !::= w++
grammar ::= r +/ ws => "grammar"
r ::= word ^"::=" alternatives /ws
ps ::= e*/ws => "ps"
| (e+/ws ws)? "^" quoted (ws e+/ws)? => "ps2"
psx ::= ps
- > ps ^"/" e /ws
+ | ps wp ^"/" ws e
sequence ::= psx
| psx ^"=>" (word|quoted) /ws