l4/pkg/ocaml/ocaml/contrib/camlp4/examples/lambda_quot_patt.ml

   1 (* Please keep me in sync with brion.inria.fr/gallium/index.php/Lambda_calculus_quotations *)
   2
   3 open Camlp4.PreCast;;
   4 module CamlSyntax = Camlp4OCamlParser.Make(Camlp4OCamlRevisedParser.Make(Syntax));;
   5
   6 let patt_of_string = CamlSyntax.Gram.parse_string CamlSyntax.patt_eoi;;
   7
   8 module LambdaGram = MakeGram(Lexer);;
   9
  10 let term = LambdaGram.Entry.mk "term";;
  11 let term_eoi = LambdaGram.Entry.mk "lambda term quotation";;
  12
  13 Camlp4_config.antiquotations := true;;
  14
  15 EXTEND LambdaGram
  16   GLOBAL: term term_eoi;
  17   term:
  18     [ "top"
  19       [ "fun"; v = var; "->"; t = term -> <:patt< `Lam($v$, $t$) >> ]
  20     | "app"
  21       [ t1 = SELF; t2 = SELF           -> <:patt< `App($t1$, $t2$) >> ]
  22     | "simple"
  23       [ `ANTIQUOT((""|"term"), a)      -> patt_of_string _loc a
  24       | v = var                        -> <:patt< `Var($v$) >>
  25       | "("; t = term; ")"             -> t ]
  26     ];
  27   var:
  28     [[ v = LIDENT               -> <:patt< $str:v$ >>
  29      | `ANTIQUOT((""|"var"), a) -> patt_of_string _loc a
  30     ]];
  31   term_eoi:
  32     [[ t = term; `EOI -> t ]];
  33 END;;
  34
  35 let expand_lambda_quot_patt loc _loc_name_opt quotation_contents =
  36   LambdaGram.parse_string term_eoi loc quotation_contents;;
  37
  38 (* function <:lam< fun x -> $(t|u)$ >> -> ... *)
  39 Syntax.Quotation.add "lam" Syntax.Quotation.DynAst.patt_tag expand_lambda_quot_patt;;
  40
  41 Syntax.Quotation.default := "lam";;