diff --git a/extra/peg/ebnf/ebnf-tests.factor b/extra/peg/ebnf/ebnf-tests.factor
index 0eeab7c4dc..a308b9af52 100644
--- a/extra/peg/ebnf/ebnf-tests.factor
+++ b/extra/peg/ebnf/ebnf-tests.factor
@@ -9,27 +9,91 @@ IN: temporary
 ] unit-test
 
 { T{ ebnf-terminal f "55" } } [
-  "\"55\"" 'terminal' parse parse-result-ast 
+  "'55'" 'terminal' parse parse-result-ast 
+] unit-test
+
+{
+  T{ ebnf-rule f 
+     "digit"
+     V{ 
+       T{ ebnf-choice f
+          V{ T{ ebnf-terminal f "1" } T{ ebnf-terminal f "2" } }
+       }
+       f
+     }
+  } 
+} [
+  "digit = '1' | '2'" 'rule' parse parse-result-ast
 ] unit-test
 
 {
   T{ ebnf-rule f 
      "digit" 
-     T{ ebnf-choice f
-        V{ T{ ebnf-terminal f "1" } T{ ebnf-terminal f "2" } }
+     V{
+       T{ ebnf-sequence f
+          V{ T{ ebnf-terminal f "1" } T{ ebnf-terminal f "2" } }
+       }
+       f
      }
-  } 
+  }   
 } [
-  "digit = \"1\" | \"2\"" 'rule' parse parse-result-ast
+  "digit = '1' '2'" 'rule' parse parse-result-ast
 ] unit-test
 
 {
-  T{ ebnf-rule f 
-     "digit" 
-     T{ ebnf-sequence f
-        V{ T{ ebnf-terminal f "1" } T{ ebnf-terminal f "2" } }
+  T{ ebnf-choice f
+     V{ 
+       T{ ebnf-sequence f
+          V{ T{ ebnf-non-terminal f "one" } T{ ebnf-non-terminal f "two" } }
+       }
+       T{ ebnf-non-terminal f "three" }
      }
   } 
 } [
-  "digit = \"1\" \"2\"" 'rule' parse parse-result-ast
-] unit-test
\ No newline at end of file
+  "one two | three" 'choice' parse parse-result-ast
+] unit-test
+
+{
+  T{ ebnf-sequence f
+     V{ 
+       T{ ebnf-non-terminal f "one" }
+       T{ ebnf-choice f
+          V{ T{ ebnf-non-terminal f "two" } T{ ebnf-non-terminal f "three" } }
+       }
+     }
+  } 
+} [
+  "one (two | three)" 'choice' parse parse-result-ast
+] unit-test
+
+{
+  T{ ebnf-sequence f
+     V{ 
+       T{ ebnf-non-terminal f "one" }
+       T{ ebnf-repeat0 f
+          T{ ebnf-sequence f
+             V{
+                T{ ebnf-choice f
+                   V{ T{ ebnf-non-terminal f "two" } T{ ebnf-non-terminal f "three" } }
+                }
+                T{ ebnf-non-terminal f "four" }
+             }
+          }
+        }
+     }
+  } 
+} [
+  "one {(two | three) four}" 'choice' parse parse-result-ast
+] unit-test
+
+{
+  T{ ebnf-sequence f
+     V{ 
+         T{ ebnf-non-terminal f "one" } 
+         T{ ebnf-optional f T{ ebnf-non-terminal f "two" } }
+         T{ ebnf-non-terminal f "three" }
+     }
+  } 
+} [
+  "one [ two ] three" 'choice' parse parse-result-ast
+] unit-test
diff --git a/extra/peg/ebnf/ebnf.factor b/extra/peg/ebnf/ebnf.factor
index 8726581488..e55ee9d852 100644
--- a/extra/peg/ebnf/ebnf.factor
+++ b/extra/peg/ebnf/ebnf.factor
@@ -1,6 +1,7 @@
 ! Copyright (C) 2007 Chris Double.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel parser words arrays strings math.parser sequences namespaces peg ;
+USING: kernel parser words arrays strings math.parser sequences 
+       quotations vectors namespaces math assocs continuations peg ;
 IN: peg.ebnf
 
 TUPLE: ebnf-non-terminal symbol ;
@@ -8,7 +9,9 @@ TUPLE: ebnf-terminal symbol ;
 TUPLE: ebnf-choice options ;
 TUPLE: ebnf-sequence elements ;
 TUPLE: ebnf-repeat0 group ;
+TUPLE: ebnf-optional elements ;
 TUPLE: ebnf-rule symbol elements ;
+TUPLE: ebnf-action word ;
 TUPLE: ebnf rules ;
 
 C: <ebnf-non-terminal> ebnf-non-terminal
@@ -16,58 +19,82 @@ C: <ebnf-terminal> ebnf-terminal
 C: <ebnf-choice> ebnf-choice
 C: <ebnf-sequence> ebnf-sequence
 C: <ebnf-repeat0> ebnf-repeat0
+C: <ebnf-optional> ebnf-optional
 C: <ebnf-rule> ebnf-rule
+C: <ebnf-action> ebnf-action
 C: <ebnf> ebnf
 
-GENERIC: ebnf-compile ( ast -- quot )
+SYMBOL: parsers
+SYMBOL: non-terminals
+SYMBOL: last-parser
 
-M: ebnf-terminal ebnf-compile ( ast -- quot )
-  [
-    ebnf-terminal-symbol , \ token ,
-  ] [ ] make ;
+: reset-parser-generation ( -- ) 
+  V{ } clone parsers set 
+  H{ } clone non-terminals set 
+  f last-parser set ;
 
-M: ebnf-non-terminal ebnf-compile ( ast -- quot )
-  [
-    ebnf-non-terminal-symbol , \ in , \ get , \ lookup , \ execute ,
-  ] [ ] make ;
+: store-parser ( parser -- number )
+  parsers get [ push ] keep length 1- ;
 
-M: ebnf-choice ebnf-compile ( ast -- quot )
-  [
-    [
-      ebnf-choice-options [
-        ebnf-compile ,
-      ] each
-    ] { } make ,
-    [ call ] , \ map , \ choice , 
-  ] [ ] make ;
+: get-parser ( index -- parser )
+  parsers get nth ;
+  
+: non-terminal-index ( name -- number )
+  dup non-terminals get at [
+    nip
+  ] [
+    f store-parser [ swap non-terminals get set-at ] keep
+  ] if* ;
 
-M: ebnf-sequence ebnf-compile ( ast -- quot )
-  [
-    [
-      ebnf-sequence-elements [
-        ebnf-compile ,
-      ] each
-    ] { } make ,
-    [ call ] , \ map , \ seq , 
-  ] [ ] make ;
+GENERIC: (generate-parser) ( ast -- id )
 
-M: ebnf-repeat0 ebnf-compile ( ast -- quot )
-  [
-    ebnf-repeat0-group ebnf-compile % \ repeat0 , 
-  ] [ ] make ;
+: generate-parser ( ast -- id )
+  (generate-parser) dup last-parser set ;
 
-M: ebnf-rule ebnf-compile ( ast -- quot )
-  [
-    dup ebnf-rule-symbol , \ in , \ get , \ create , 
-    ebnf-rule-elements ebnf-compile , \ define-compound , 
-  ] [ ] make ;
+M: ebnf-terminal (generate-parser) ( ast -- id )
+  ebnf-terminal-symbol token sp store-parser ;
 
-M: ebnf ebnf-compile ( ast -- quot )
+M: ebnf-non-terminal (generate-parser) ( ast -- id )
   [
-    ebnf-rules [
-      ebnf-compile %
-    ] each 
-  ] [ ] make ;
+    ebnf-non-terminal-symbol dup non-terminal-index , 
+    parsers get , \ nth , [ search ] [ 2drop f ] recover , \ or ,
+  ] [ ] make delay sp store-parser ;
+
+M: ebnf-choice (generate-parser) ( ast -- id )
+  ebnf-choice-options [
+    generate-parser get-parser 
+  ] map choice store-parser ;
+
+M: ebnf-sequence (generate-parser) ( ast -- id )
+  ebnf-sequence-elements [
+    generate-parser get-parser
+  ] map seq store-parser ;
+
+M: ebnf-repeat0 (generate-parser) ( ast -- id )
+  ebnf-repeat0-group generate-parser get-parser repeat0 store-parser ;
+
+M: ebnf-optional (generate-parser) ( ast -- id )
+  ebnf-optional-elements generate-parser get-parser optional store-parser ;
+
+M: ebnf-rule (generate-parser) ( ast -- id )
+  dup ebnf-rule-symbol non-terminal-index swap 
+  ebnf-rule-elements generate-parser get-parser ! nt-id body
+  swap [ parsers get set-nth ] keep ;
+
+M: ebnf-action (generate-parser) ( ast -- id )
+  ebnf-action-word search 1quotation 
+  last-parser get get-parser swap action store-parser ;
+
+M: vector (generate-parser) ( ast -- id )
+  [ generate-parser ] map peek ;
+
+M: f (generate-parser) ( ast -- id )
+  drop last-parser get ;
+
+M: ebnf (generate-parser) ( ast -- id )
+  ebnf-rules [
+    generate-parser 
+  ] map peek ;
 
 DEFER: 'rhs'
 
@@ -75,32 +102,55 @@ DEFER: 'rhs'
   CHAR: a CHAR: z range repeat1 [ >string <ebnf-non-terminal> ] action ;
 
 : 'terminal' ( -- parser )
-  "\"" token hide [ CHAR: " = not ] satisfy repeat1 "\"" token hide 3array seq [ first >string <ebnf-terminal> ] action ;
+  "'" token hide [ CHAR: ' = not ] satisfy repeat1 "'" token hide 3array seq [ first >string <ebnf-terminal> ] action ;
 
 : 'element' ( -- parser )
   'non-terminal' 'terminal' 2array choice ;
 
-: 'sequence' ( -- parser )
-  'element' sp 
-  "|" token sp ensure-not 2array seq [ first ] action 
-   repeat1 [ <ebnf-sequence> ] action ;
-  
-: 'choice' ( -- parser )
-  'element' sp "|" token sp list-of [ <ebnf-choice> ] action ;
+DEFER: 'choice'
+
+: 'group' ( -- parser )
+  "(" token sp hide
+  [ 'choice' sp ] delay
+  ")" token sp hide 
+  3array seq [ first ] action ;
 
 : 'repeat0' ( -- parser )
   "{" token sp hide
-  [ 'rhs' sp ] delay
+  [ 'choice' sp ] delay
   "}" token sp hide 
   3array seq [ first <ebnf-repeat0> ] action ;
 
-: 'rhs' ( -- parser )
-  'repeat0'
-  'sequence'
-  'choice'
-  'element' 
-  4array choice ;
+: 'optional' ( -- parser )
+  "[" token sp hide
+  [ 'choice' sp ] delay
+  "]" token sp hide 
+  3array seq [ first <ebnf-optional> ] action ;
+
+: 'sequence' ( -- parser )
+  [ 
+    'element' sp ,
+    'group' sp , 
+    'repeat0' sp ,
+    'optional' sp , 
+   ] { } make  choice  
+   repeat1 [ 
+     dup length 1 = [ first ] [ <ebnf-sequence> ] if
+   ] action ;  
+
+: 'choice' ( -- parser )
+  'sequence' sp "|" token sp list-of [ 
+    dup length 1 = [ first ] [ <ebnf-choice> ] if
+   ] action ;
+
+: 'action' ( -- parser )
+  "=>" token hide
+  [ blank? ] satisfy ensure-not [ drop t ] satisfy 2array seq [ first ] action repeat1 [ >string ] action sp
+  2array seq [ first <ebnf-action> ] action ;
   
+: 'rhs' ( -- parser )
+  'choice' 'action' sp optional 2array seq ;
+ 
 : 'rule' ( -- parser )
   'non-terminal' [ ebnf-non-terminal-symbol ] action 
   "=" token sp hide 
@@ -112,9 +162,23 @@ DEFER: 'rhs'
 
 : ebnf>quot ( string -- quot )
   'ebnf' parse [
-     parse-result-ast ebnf-compile  
+     parse-result-ast [
+         reset-parser-generation
+         generate-parser drop
+         [
+             non-terminals get
+             [
+               get-parser [
+                 swap , \ in , \ get , \ create ,
+                 1quotation , \ define-compound , 
+               ] [
+                 drop
+               ] if*
+             ] assoc-each
+         ] [ ] make
+     ] with-scope
    ] [
     f
    ] if* ;
 
-: <EBNF "EBNF>" parse-tokens "" join ebnf>quot call ; parsing
\ No newline at end of file
+: <EBNF "EBNF>" parse-tokens " " join ebnf>quot call ; parsing
\ No newline at end of file
diff --git a/extra/peg/peg.factor b/extra/peg/peg.factor
index a9e08f6024..8940fc87c6 100644
--- a/extra/peg/peg.factor
+++ b/extra/peg/peg.factor
@@ -1,14 +1,16 @@
 ! Copyright (C) 2007 Chris Double.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel sequences strings namespaces math assocs shuffle vectors combinators.lib ;
+USING: kernel sequences strings namespaces math assocs shuffle 
+       vectors arrays combinators.lib ;
 IN: peg
 
 TUPLE: parse-result remaining ast ;
 
-GENERIC: parse ( state parser -- result )
+GENERIC: (parse) ( state parser -- result )
 
 <PRIVATE
 
+SYMBOL: packrat-cache
 SYMBOL: ignore 
 
 : <parse-result> ( remaining ast -- parse-result )
@@ -24,18 +26,48 @@ TUPLE: parser id ;
 : init-parser ( parser -- parser )
   get-next-id parser construct-boa over set-delegate ;
 
+: from ( slice-or-string -- index )
+  dup slice? [ slice-from ] [ drop 0 ] if ;
+
+: get-cached ( input parser -- result )
+  [ from ] dip parser-id packrat-cache get at at ;
+
+: put-cached ( result input parser -- )
+  parser-id dup packrat-cache get at [ 
+    nip
+  ] [ 
+    H{ } clone dup >r swap packrat-cache get set-at r>
+  ] if* 
+  [ from ] dip set-at ;
+
+PRIVATE>
+
+: parse ( input parser -- result )
+  packrat-cache get [
+    2dup get-cached [
+      [ (parse) dup ] 2keep put-cached
+    ] unless* 
+  ] [
+    (parse)
+  ] if ;
+
+: packrat-parse ( input parser -- result )
+  H{ } clone packrat-cache [ parse ] with-variable ;
+
+<PRIVATE
+
 TUPLE: token-parser symbol ;
 
-M: token-parser parse ( state parser -- result )
+M: token-parser (parse) ( input parser -- result )
   token-parser-symbol 2dup head? [
     dup >r length tail-slice r> <parse-result>
   ] [
     2drop f
   ] if ;
-
+   
 TUPLE: satisfy-parser quot ;
 
-M: satisfy-parser parse ( state parser -- result )
+M: satisfy-parser (parse) ( state parser -- result )
   over empty? [
     2drop f 
   ] [
@@ -48,7 +80,7 @@ M: satisfy-parser parse ( state parser -- result )
 
 TUPLE: range-parser min max ;
 
-M: range-parser parse ( state parser -- result )
+M: range-parser (parse) ( state parser -- result )
   over empty? [
     2drop f
   ] [
@@ -77,7 +109,7 @@ TUPLE: seq-parser parsers ;
     drop   
   ] if ;
 
-M: seq-parser parse ( state parser -- result )
+M: seq-parser (parse) ( state parser -- result )
   seq-parser-parsers [ V{ } clone <parse-result> ] dip  (seq-parser) ;
 
 TUPLE: choice-parser parsers ;
@@ -93,7 +125,7 @@ TUPLE: choice-parser parsers ;
     ] if* 
   ] if ;
 
-M: choice-parser parse ( state parser -- result )
+M: choice-parser (parse) ( state parser -- result )
   choice-parser-parsers (choice-parser) ;
 
 TUPLE: repeat0-parser p1 ;
@@ -111,7 +143,7 @@ TUPLE: repeat0-parser p1 ;
   { parse-result-remaining parse-result-ast }
   get-slots 1vector  <parse-result> ;
 
-M: repeat0-parser parse ( state parser -- result )
+M: repeat0-parser (parse) ( state parser -- result )
      repeat0-parser-p1 2dup parse [ 
        nipd clone-result (repeat-parser) 
      ] [ 
@@ -120,17 +152,17 @@ M: repeat0-parser parse ( state parser -- result )
 
 TUPLE: repeat1-parser p1 ;
 
-M: repeat1-parser parse ( state parser -- result )
+M: repeat1-parser (parse) ( state parser -- result )
    repeat1-parser-p1 tuck parse dup [ clone-result (repeat-parser) ] [ nip ] if ;
 
 TUPLE: optional-parser p1 ;
 
-M: optional-parser parse ( state parser -- result )
+M: optional-parser (parse) ( state parser -- result )
    dupd optional-parser-p1 parse swap f <parse-result> or ;
 
 TUPLE: ensure-parser p1 ;
 
-M: ensure-parser parse ( state parser -- result )
+M: ensure-parser (parse) ( state parser -- result )
    dupd ensure-parser-p1 parse [
      ignore <parse-result>  
    ] [
@@ -139,7 +171,7 @@ M: ensure-parser parse ( state parser -- result )
 
 TUPLE: ensure-not-parser p1 ;
 
-M: ensure-not-parser parse ( state parser -- result )
+M: ensure-not-parser (parse) ( state parser -- result )
    dupd ensure-not-parser-p1 parse [
      drop f
    ] [
@@ -148,7 +180,7 @@ M: ensure-not-parser parse ( state parser -- result )
 
 TUPLE: action-parser p1 quot ;
 
-M: action-parser parse ( state parser -- result )
+M: action-parser (parse) ( state parser -- result )
    tuck action-parser-p1 parse dup [ 
      dup parse-result-ast rot action-parser-quot call
      swap [ set-parse-result-ast ] keep
@@ -165,12 +197,12 @@ M: action-parser parse ( state parser -- result )
 
 TUPLE: sp-parser p1 ;
 
-M: sp-parser parse ( state parser -- result )
+M: sp-parser (parse) ( state parser -- result )
   [ left-trim-slice ] dip sp-parser-p1 parse ;
 
 TUPLE: delay-parser quot ;
 
-M: delay-parser parse ( state parser -- result )
+M: delay-parser (parse) ( state parser -- result )
   delay-parser-quot call parse ;
 
 PRIVATE>
diff --git a/extra/peg/pl0/pl0-tests.factor b/extra/peg/pl0/pl0-tests.factor
index e40c984660..cec7b24cd0 100644
--- a/extra/peg/pl0/pl0-tests.factor
+++ b/extra/peg/pl0/pl0-tests.factor
@@ -5,9 +5,9 @@ USING: kernel tools.test peg peg.pl0 ;
 IN: temporary
 
 { "abc" } [
-  "abc" 'ident' parse parse-result-ast 
+  "abc" ident parse parse-result-ast 
 ] unit-test
 
 { 55 } [
-  "55abc" 'number' parse parse-result-ast 
+  "55abc" number parse parse-result-ast 
 ] unit-test
diff --git a/extra/peg/pl0/pl0.factor b/extra/peg/pl0/pl0.factor
index 8a01057bfb..b37009238d 100644
--- a/extra/peg/pl0/pl0.factor
+++ b/extra/peg/pl0/pl0.factor
@@ -1,58 +1,29 @@
 ! Copyright (C) 2007 Chris Double.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel arrays strings math.parser sequences peg ;
+USING: kernel arrays strings math.parser sequences peg peg.ebnf ;
 IN: peg.pl0
 
 #! Grammar for PL/0 based on http://en.wikipedia.org/wiki/PL/0
-
-: 'ident' ( -- parser )
+: ident ( -- parser )
   CHAR: a CHAR: z range 
   CHAR: A CHAR: Z range 2array choice repeat1 
   [ >string ] action ;
 
-: 'number' ( -- parser )
+: number ( -- parser )
   CHAR: 0 CHAR: 9 range repeat1 [ string>number ] action ;
 
-DEFER: 'factor'
-
-: 'term' ( -- parser )
-  'factor' "*" token "/" token 2array choice sp 'factor' sp 2array seq repeat0 2array seq ;
-
-: 'expression' ( -- parser )
-  [ "+" token "-" token 2array choice sp optional 'term' sp 2dup 2array seq repeat0 3array seq ] delay ;
-
-: 'factor' ( -- parser )
-  'ident' 'number' "(" token hide 'expression' sp ")" token sp hide 3array seq 3array choice ;
-
-: 'condition' ( -- parser )
-  "odd" token 'expression' sp 2array seq
-  'expression' { "=" "#" "<=" "<" ">=" ">" } [ token ] map choice sp 'expression' sp 3array seq 
-  2array choice ;
-
-: 'statement' ( -- parser )
-  [
-    'ident' ":=" token sp 'expression' sp 3array seq
-    "call" token 'ident' sp 2array seq
-    "begin" token 'statement' sp ";" token sp 'statement' sp 2array seq repeat0 "end" token sp 4array seq
-     "if" token 'condition' sp "then" token sp 'statement' sp 4array seq
-     4array choice
-     "while" token 'condition' sp "do" token sp 'statement' sp 4array seq
-     2array choice optional
-  ] delay ;
-
-: 'block' ( -- parser )
- [
-  "const" token 'ident' sp "=" token sp 'number' sp 4array seq 
-    "," token sp 'ident' sp "=" token sp 'number' sp 4array seq repeat0
-  ";" token sp 3array seq optional
-  
-  "var" token 'ident' sp "," token sp 'ident' sp 2array seq repeat0 
-  ";" token sp 4array seq optional
-
-  "procedure" token 'ident' sp ";" token sp 'block' sp 4array seq ";" token sp 2array seq repeat0 'statement' sp 2array seq  
-
-  3array seq
- ] delay ;
-
-: 'program' ( -- parser )
-  'block' "." token sp 2array seq ;
+<EBNF
+program = block '.' .
+block = [ 'const' ident '=' number { ',' ident '=' number } ';' ]
+        [ 'var' ident { ',' ident } ';' ]
+        { 'procedure' ident ';' [ block ';' ] } statement .
+statement = [ ident ':=' expression | 'call' ident |
+              'begin' statement {';' statement } 'end' |
+              'if' condition 'then' statement |
+              'while' condition 'do' statement ] .
+condition = 'odd' expression |
+            expression ('=' | '#' | '<=' | '<' | '>=' | '>') expression .
+expression = ['+' | '-'] term {('+' | '-') term } .
+term = factor {('*' | '/') factor } .
+factor = ident | number | '(' expression ')'
+EBNF>