self describing parser language

parser.prs

ident::& ([$_A-Za-z]*);;
pat  ::& (\(.*\))     ;;
item ::| ident pat    ;;
stmt ::& expr (\;\;)  ;;
list ::* item         ;;
and  ::& (\:\:\&) list;;
or   ::& (\:\:\|) list;;
arr  ::& (\:\:\*) list;;
expr ::| and or arr   ;;
prog ::* expr         ;;

parser.yml

prog:
  ident: [ "&", "[$_A-Za-z]*"]
  pat  : [ "&", "\\(.*\\)"   ]
  item : [ "|", ident, pat   ]
  stmt : [ "&", expr, ";;"   ]
  list : [ "*", item         ]
  and  : [ "&", "::&", list  ]
  or   : [ "&", "::|", list  ]
  arr  : [ "&", "::*", list  ]
  expr : [ "|", and, or, arr ]
  prog : [ "*", expr         ]