1 files changed, 34 insertions, 0 deletions
diff --git a/camlp4/examples/lambda_parser.ml b/camlp4/examples/lambda_parser.ml
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+++ b/camlp4/examples/lambda_parser.ml
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+(* Please keep me in sync with brion.inria.fr/gallium/index.php/Lambda_calculus_quotations *)
+
+type term =
+  | Lam of var * term
+  | App of term * term
+  | Int of int
+  | Var of var
+and var = string
+
+module LambdaGram = Camlp4.PreCast.MakeGram(Camlp4.PreCast.Lexer);;
+module Loc = Camlp4.PreCast.Loc;; (* should not be necessary when camlp4 will be fixed *)
+open Camlp4.Sig;; (* from tokens *)
+let term = LambdaGram.Entry.mk "term";;
+let term_eoi = LambdaGram.Entry.mk "lambda term quotation";;
+
+EXTEND LambdaGram
+  GLOBAL: term term_eoi;
+  term:
+    [ "top"
+      [ "fun"; v = var; "->"; t = term -> Lam(v, t) ]
+    | "app"
+      [ t1 = SELF; t2 = SELF           -> App(t1, t2) ]
+    | "simple"
+      [ v = var                        -> Var(v)
+      | `INT(i, _)                     -> Int(i)
+      | "("; t = term; ")"             -> t ]
+    ];
+  var:
+    [[ `LIDENT v -> v ]];
+  term_eoi:
+    [[ t = term; `EOI -> t ]];
+END;;
+
+let lambda_parser = LambdaGram.parse_string term_eoi;;