Here is a simple ocaml file, just meant to get me to understand how to load a program that uses the Batteries library into the ocamltop.
batteryassault.ml
open Batteries
let main = print_string "hello, world ... powered on"
I compile this to bytecode with
ocamlfind ocamlc -package batteries -linkpkg batteryassault.ml
Resulting in batteryassault.cmo and batteryassault.cmi, and no errors nor warnings. Then, I start the battery-powered ocamltop with
rlwrap ocamlfind batteries/ocaml
Finally, to load the file in ocamltop:
#load "batteryassault.cmo" ;;
And then we get an error.
The files batteryassault.cmo and /usr/lib/ocaml/batteries/batteries.cma
disagree over interface Batteries
I think what could be going on is that Ubuntu installs batteries 2.2.1, but for some reason (installing merlin?) I have batteries 2.3.1 installed in my opam folder, and moreover, when starting the ocamltop with batteries as above, it indicates that ocamltop is using the 2.2.1 version. Further, compiling with
ocamlfind ocamlc -package batteries -linkpkg batteryassault.ml -verbose
I find that ocamlc is definitely using the library in opam, i.e. the 2.3.1 version.
So my question is: what is the/is there a workaround?
Usually I suggest to remove system OCaml installation at all. Otherwise you may have such errors.
You should ensure, that all your tools and libraries come from the same source, in this particular case from opam.
A usual error is to forget to call for
eval `opam config env`
at some point. You may recall later about this, and activate your opam, thus ending up, with parts of your application, or even opam stack built using opam with other parts built with system libraries. If you made such error, it will be hard to guess, when and what goes wrong.
But if you still don't want to remove system batteries, then you need to be very careful. For example, since ocamlfind batteries/ocaml results in loading old version of batteries, then you can try to use this trick, to make sure that batteries topleve is loaded from opam:
$ `opam config var batteries:lib`/ocaml
If the problem persists, that means that your system is really broken. Consider removing you opam stack and making carefully everything from scratch. E.g.,
rm -rf ~/.opam
opam init --comp=4.02.1
eval `opam config env`
opam install batteries
Related
I'm using Ubuntu 18.04. I have OCaml 4.05 installed (via apt-get) as well as utop and Core (via opam). And this is the content of my ~/.ocamlinit:
(* Added by OPAM. *)
let () =
try Topdirs.dir_directory (Sys.getenv "OCAML_TOPLEVEL_PATH")
with Not_found -> ()
;;
#use "topfind";;
#thread;;
#camlp4o;;
#require "core.top";;
#require "core.syntax";;
Compiling OCaml codes which use Core works fine with corebuild. It doesn't work with plain ocamlc or ocamlopt though. They complain:
Error: Unbound module Core
And I found corebuild to be pretty picky. It doesn't like any existing non-OCaml codes in the same directory:
SANITIZE: a total of 12 files that should probably not be in your source tree
has been found. A script shell file "/home/anta40/Codes/_build/sanitize.sh"
is being created. Check this script and run it to remove unwanted files or
use other options (such as defining hygiene exceptions or using the
-no-hygiene option).
IMPORTANT: I cannot work with leftover compiled files.
ERROR: Leftover object files:
File hellod.o in . has suffix .o
File helloscheme_.o in . has suffix .o
File nqueens.o in . has suffix .o
File helloscheme.o in . has suffix .o
File HelloHS.o in . has suffix .o
File helloml.o in . has suffix .o
ERROR: Leftover OCaml compilation files:
File nqueens.cmo in . has suffix .cmo
File helloml.cmo in . has suffix .cmo
File helloml.cmi in . has suffix .cmi
File nqueens.cmi in . has suffix .cmi
File nqueens.cmx in . has suffix .cmx
File helloml.cmx in . has suffix .cmx
Exiting due to hygiene violations.
Compilation unsuccessful after building 0 targets (0 cached) in 00:00:00.
Using the -no-hygiene option, e.g corebuild sum.ml -no-hygiene doesn't produce any native executable. Is there any workaround?
`
The OPAM package manager can support multiple OCaml instances, where each groups an OCaml installation (ocaml, ocamlc, ocamlopt, etc.) with installed packages. Each instance is called a switch.
Type ocaml switch to see a list of instances. In terms of switches, the installation of OCaml using packages (apt-get) is called system.
It may be better to avoid mixing the system and OPAM installations. I suggest that you create a new switch, ensure that the OPAM settings are properly sourced, and install Core into it the new switch :
opam switch 4.06.1
eval $(opam config env)
opam install core
The automatic build tools assume that they control the entire build process and complain when they find other compilation results. Normally, running the suggested shell script and retrying side-steps the problem, even if only to uncover another one. Your second problem (with -no-hygeine) may be related to the installation issues.
Your installation is dated.
I imagine that you followed instructions in Real World OCaml but OCaml ecosystem has moved since the first edition of RWO. To get a modern installation you should follow the dev version of Real World OCaml https://dev.realworldocaml.org/install.html .
To answer your question, corebuild is a fine wrapper around ocamlbuild. To build an executable from a sum.ml with corebuild, you should use
corebuild sum.native
for native executable or
corebuild sum.byte
for bytecode compilation
Otherwise, you can invoke ocamlopt through ocamlfind:
ocamlfind ocamlopt -package core sum.ml
Finally, if you intend to build larger project, you ought to have a look to dune https://jbuilder.readthedocs.io/en/latest/overview.html .
I have a file main.ml that uses some package that makes the command ocaml main.ml fail and report this error:
Error: Unbound module X
And the only solution I've found so far is to run:
ocamlbuild main.native -use-ocamlfind -package X
./main.native
But this compiles the file. Is there a way to just run the regular ocaml interpreter (ocaml main.ml) with some additional flags to make it find the package?
The easiest way is probably to use topfind and add #require "core" at the top of your file. If you want to avoid adding toplevel directives in your file, you can use ocamlfind query -i-format -r to compute the required include directories:
ocaml $(ocamlfind query -i-format -r core) main.ml
You can put at the beginning of your file some top-level directives which find and load needed modules. For example, when I want to use Core library in my script I insert:
#use "topfind";;
#thread;;
#require "core";;
open Core.Std
(* Code of my script *)
To use topfind package ocamlfind has to be installed (opam install ocamlfind)
You can also query the path of your package to ocamlfind :
ocamlfind query package_X
That will return the path of your package : /path_to/packageX
And then :
ocaml main.ml -I /path_to/packageX
I am trying to generate documentation for a module of mine using ocamldoc. However, I use the Core library and ocamldoc complains about not finding it.
Error: Unbound module Core
I understand why thanks to this question, but it doesn't mention any solution for standard modules.
Any help?
ocamldoc needs to see the compiled interface for Core, i.e. the file core.cmi. This can be done through one of the following mechanisms:
Add the -I dir option to ocamldoc where dir is the directory where the core.cmi file lies. So for example ocamldoc -I $(opam config var core:lib) ... should do.
If you use the ocamlfind indirection, add -package core to the command line. E.g. ocamlfind ocamldoc -package core
I am trying to use ocamlfind to install a library. I am using OCamlMakeFile. Here is my Makefile:
OCAMLMAKEFILE = OCamlMakeFile
RESULT = owebl
SOURCES = src/utils.ml src/verb.ml src/request.ml src/template.ml src/response.ml src/rule.ml src/handler.ml src/server.ml
PACKS = unix str
all: native-code-library byte-code-library
install: libinstall
uninstall: libuninstall
include $(OCAMLMAKEFILE)
So basically the library is a collection of modules that I want to distribute. A basic usage of the library is (main.ml):
open Response
open Rule
open Verb
open Server
let handler =
Handler.create
(StaticRouteRule.create "/" [GET])
(FileResponse.create
~static_file:(FileResponse.StaticFile "/index.html")
())
let server = Server.create "0.0.0.0" 8080 [handler];;
server#serve
I compile the library just by running "make". It generates three files: "owebl.a, owebl.cma, owebl.cmxa". Then I install the library using ocamlfind:
ocamlfind install owebl META owebl.a owebl.cma owebl.cmxa
Oh, the META file is:
version = "0.1"
name = "OWebl"
description = "A Web Framework for OCaml"
archive(byte) = "owebl.cma"
archive(native) = "owebl.cmxa"
requires = "unix,str"
Everything works until I try to compile the above example that uses the library. I run:
ocamlbuild -use-ocamlfind -pkgs owebl main.native
And I get:
ocamlbuild -use-ocamlfind -pkgs owebl main.native
+ ocamlfind ocamlc -c -package owebl -o main.cmo main.ml
File "main.ml", line 1, characters 5-10:
Error: Unbound module Owebl
Command exited with code 2.
Hint: Recursive traversal of subdirectories was not enabled for this build,
as the working directory does not look like an ocamlbuild project (no
'_tags' or 'myocamlbuild.ml' file). If you have modules in subdirectories,
you should add the option "-r" or create an empty '_tags' file.
To enable recursive traversal for some subdirectories only, you can use the
following '_tags' file:
true: -traverse
<dir1> or <dir2>: traverse
Compilation unsuccessful after building 2 targets (1 cached) in 00:00:00.
make: *** [fileserver] Error 10
I tried adding open Owebl to the beginning of main.ml but I just got "unbound module Owebl" similarly. I'm pretty lost as to why these modules are all unbound. What am I missing?
You should use LIB_PACK_NAME variable if you want to pack your modules under umbrella namespace, like OWebl, otherwise they will be available just as it is, e.g. Response, Rule, etc. Also, you should specify the mli files as well as ml files in SOURCES variable. And finally, you shouldn't forget to install cmi files, as well as .a files. Installing mli files is also considered a good tradition, although is not strictly required. Also, consider using OCamlMakefile installation facilities instead of custom installation script.
I am no longer using OCamlMakefile therefore am not sure, but assuming OCamlMakefile compiles things with -for-pack OWebl option and properly builds a packaged module owebl.cmo, you also need to install owebl.cmi.
OCaml compiler seeks cmi files to check the existence of modules and to get their type information. If not installed, the compiler cannot find it. cma and cmxa files are collections of objects and do not provide type information.
I'm trying to use ocamlfind with both the OCaml compiler and toplevel. From what I understood, I need to place the required libraries in the _tags file at the root of my project, so that the ocamlfind tool will take care of loading them - allowing me to open them in my modules like so :
open Sdl
open Sdlvideo
open Str
Currently, my _tags file looks like this :
<*>: pkg_sdl,pkg_str
I can apparently launch the ocamlfind command with the ocamlc or ocamlopt argument, provided I wan't to compile my project, but I did not see an option to launch the toplevel in the same manner. Is there any way to do this (something like "ocamlfind ocaml")?
I also don't know how to place my project specific modules in the _tags file : imagine I have a module name Land. I am currently using the #use "land.ml" directive to open the file and load the module, but it has been suggested that this is not good practice. What syntax should I use in _tags to specify it should be loaded by ocamlfind (considering land.ml is not in the ocamlfind search path) ?
Thank you,
Charlie P.
Edit : According to the first answer of this post, the _tags file is not to be used with ocamlfind. The questions above still stand, there is just a new one to the list : what is the correct way to specify the libraries to ocamlfind ?
try this:
$ cat >> .ocamlinit
#use "topfind";;
#require "sdl";;
#require "sdlvideo";;
open Sdl
open Sdlvideo;;
open Str;;
.ocamlinit is sourced from the current directory, falling back to /home/user/.ocamlinit. you can explicitly override it via ocaml -init <filename>
One should distinguish ocamlfind packages, module names and file names. Source code references only module names. Modules are provided by .cma .cmo .cmx (and .cmi) files. Ocamlfind packages are named collections of such files (binaries built from some ocaml library sources). Ocamlfind is not strictly necessary to build a project - just specify the paths to all used libraries via -I. But if the project is distributed in source form - another people will have troubles building it cause used libraries are placed in different places. Then one seeks the way to specify the names of used "third party code pieces" and some external tool to resolve those names to actual paths. This tool is ocamlfind.
First find the ocamlfind package that provides the modules you need (in this case Sdl and Sdlvideo - just run ocamlfind list, most probably the package is named sdl.
Compile with ocamlfind ocamlc -package <package name> -linkpkg source.ml -o program
Alternatively use ocamlfind to extract the path to the .cma file (and others) provided by the package (ocamlfind query <package name>) and use this path with your build tool (plain Makefile, ocamlbuild, etc).
Moreover ocamlfind (is intended to) take away the burden of remembering how the actual .cma files are named and what matching compiler options are required and in what order the packages are depending on each other. One just needs to specify the package name.
Keep in mind that there is no one-to-one strict formal relationship between library name (purely human-targeted name e.g. ocaml-extlib), module names (ExtLib, Enum, IO, etc), file names (extLib.cma) and ocamlfind package name (extlib), though for convenience package maintainers and library authors usually choose guessable names :)
The _tags file is not for ocamlfind, but for ocamlbuild.
Exemple :
ocamlbuild land.native