Reproduction files for https://github.com/ocaml-community/sedlex/issues/45.

lexer.ml

open Parser

let rec tokenizer lexbuf =
  match%sedlex lexbuf with
    | '\n' -> tokenizer lexbuf
    | Plus('0'..'9') -> NUMBER (Sedlexing.Utf8.lexeme lexbuf)
    | ';', ';' -> SEQSEQ
    | eof -> EOF
    | _ -> failwith "Parse error!"

main.ml

let interactive =
  MenhirLib.Convert.Simplified.traditional2revised Parser.interactive

let empty_p = {
  Lexing.
    pos_fname = "";
    pos_lnum = 1;
    pos_bol = 0;
    pos_cnum = 0;
}

let get_token lexbuf =
  let tokenizer () =
    (Lexer.tokenizer lexbuf, empty_p, empty_p)
  in
  interactive tokenizer

let () =
  let lexbuf = Sedlexing.Utf8.from_channel stdin in
  let rec f () =
    Printf.printf "Got number from stdin: %d\n%!" (get_token lexbuf);
    f ()
  in
  f ()

Makefile

.PHONY: clean all

x := cmx
i := cmi
V := @

OCAMLOPT := ocamlfind ocamlopt
OCAMLDEP := ocamlfind ocamldep
OCAMLFLAGS := -g -linkpkg -package sedlex -package sedlex.ppx -package menhirlib

SOURCES := parser.mli parser.ml lexer.ml main.ml

all: test

parser.mli parser.ml: parser.mly
	menhir --explain $(<)

.depend: $(SOURCES)
	$(V)echo OCAMLDEP
	$(V)$(OCAMLDEP) $(^) > $(@)

%.$(i): %.mli
	$(V)echo OCAMLOPT -c $(<)
	$(V)$(OCAMLOPT) $(OCAMLFLAGS) -c $(<)

%.$(x): %.ml
	$(V)echo OCAMLOPT -c $(<)
	$(V)$(OCAMLOPT) $(OCAMLFLAGS) -c $(<)

test: $(SOURCES:.ml=.$(x))
	$(V)echo OCAMLOPT -o $(@)
	$(V)$(OCAMLOPT) -linkpkg -o $(@) $(^) $(OCAMLFLAGS)

clean:
	rm -f .depend parser.mli parser.ml test *.o *.conflicts *.cm*

-include .depend

parser.mly

%token <string> NUMBER
%token SEQSEQ EOF

%start interactive
%type <int> interactive

%%

exprs:
  | NUMBER { int_of_string $1 }

interactive:
  | exprs SEQSEQ { $1 }
  | EOF { raise End_of_file }