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Linking to C libraries when calling camlp4
- Joseph Young
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Date: | 2010-01-29 (09:34) |
From: | Joseph Young <ocaml@o...> |
Subject: | Linking to C libraries when calling camlp4 |
Hi, How do you link to external C libraries when calling camlp4? When calling ocamlc, we can use the -custom and -cclib flags in order to statically link a library. However, the camlp4 executable seems to ignore these flags when called. As an example, given the files: ----------------- $ cat Makefile all: gcc -c myadd.c ocamlc -c myadd.ml ocamlmktop -custom -cclib myadd.o -o mytop myadd.cmo ocamlc -c -I +camlp4 -I +camlp4/Camlp4Parsers -pp camlp4of myquot.ml clean: rm *.cmo rm *.cmi rm *.o $ cat myadd.c int add1(int x){ return x+1; } $ cat myadd.ml external add1 : int->int = "add1";; $ cat myquot.ml module CamlSyntax = Camlp4OCamlParser.Make( Camlp4OCamlRevisedParser.Make(Camlp4.PreCast.Syntax));; open Camlp4.PreCast;; let expr_of_string = CamlSyntax.Gram.parse_string CamlSyntax.expr_eoi;; module MyGram = Camlp4.PreCast.MakeGram(Camlp4.PreCast.Lexer);; let term = MyGram.Entry.mk "term";; let term_eoi = MyGram.Entry.mk "term quotation";; EXTEND MyGram GLOBAL: term term_eoi; term: [ "simple" [ `INT(i,_) -> <:expr< $`int:Myadd.add1 i$ >> ] ]; term_eoi: [[ t = term; `EOI -> t ]]; END;; let expand_quot loc loc_opt s = MyGram.parse_string term_eoi loc s;; Syntax.Quotation.add "abc" Camlp4.PreCast.Syntax.Quotation.DynAst.expr_tag expand_quot;; $ cat test.ml let x= <:abc< 4 >>;; ----------------- If we call: ----------------- $ ./mytop dynlink.cma camlp4of.cma myquot.cmo Objective Caml version 3.11.2 Camlp4 Parsing version 3.11.2 # let x= <:abc< 4 >>;; val x : int = 5 # ----------------- everything works fine since mytop has been compiled with the correct C object file. However, if we try the following call: ----------------- $ camlp4of myadd.cmo myquot.cmo test.ml Camlp4: Uncaught exception: DynLoader.Error ("./myquot.cmo", "error while linking ./myquot.cmo.\nThe external function `add1' is not available") ----------------- we have an error since the C object file has not been linked. How do we correctly preprocess the file test.ml? Joe