Dependency fix

Makefile

@@ -6,28 +6,33 @@ OCAMLCFLAGS := -g
 OCAMLLDFLAGS :=
 OCAMLLDLIBS  := str.cmxa
 
+OCAMLLEX  := ocamllex
+OCAMLYACC := menhir --infer --explain --dump
+
 .PHONY: all clean
 .PRECIOUS: $(addprefix .cmi,$(BASENAMES))
 
 all: $(RESULT)
 
 %.ml: %.mll
-	ocamllex -o $@ $<
+	$(OCAMLLEX) -o $@ $<
 
 %.ml: %.mly
-	menhir --infer --explain $<
+	$(OCAMLYACC) $<
 
 %.cmi: %.mli
 	ocamlc -c $(OCAMLCFLAGS) -o $@ $<
 
-parser.cmx: parser.cmi
-parser.mli: parser.ml
-
 %.cmx: %.ml
 	ocamlfind ocamlopt -package batteries -c $(OCAMLCFLAGS) -o $@ $(<:.cmi=.ml)
 
 $(RESULT): $(OFILES)
 	ocamlopt -o $@ $(OCAMLLDFLAGS) $(OCAMLLDLIBS) $^
 
+# intra-module dependencies
+parser.cmx: parser.cmi
+parser.mli: parser.ml
+parse.cmx: lexer.cmi parser.cmi
+
 clean:
 	rm -f *.cmi *.cmx *.o lexer.ml parser.ml parser.mli $(RESULT)