# Held back by inability to access libraries **URL:** \ **Category:** Learning\ **Created:** [December 13, 2023, 11:51am UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628 "2023-12-13T11:51:11Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![dalegard](https://avatars.discourse-cdn.com/v4/letter/d/8dc957/32.png) [@dalegard](https://discuss.ocaml.org/u/dalegard)\ **Post date:** [December 13, 2023, 11:51am UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/1 "2023-12-13T11:51:11Z")
I’m sure this question has been asked and answered many times, but I am unable to install and then access many of the great libraries created by the Ocaml community. Take Base as an example. I run: `opam install Base` It shows up when I run: `opam list` but if I use the REPL to open it, or try to include it in a script, I get the dreaded ‘Unbound module’ error. I have seen various answers online referring to an ‘.ocamlinit’ file, but I have no idea where it is located or what to do with it. I am a F# refugee, so some of the extra work needed to get Ocaml working correctly is foreign to me. Any (simple) instructions gratefully received. ---
**Author:** ![nojb](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/nojb/32/519_2.png) [@nojb](https://discuss.ocaml.org/u/nojb)\ **Post date:** [December 13, 2023, 12:09pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/2 "2023-12-13T12:09:19Z")
To use `base` in the `ocaml` toplevel after installing it, you need to type: ```auto #use "topfind";; #require "base";; ``` Cheers, Nicolas ---
**Author:** ![dalegard](https://avatars.discourse-cdn.com/v4/letter/d/8dc957/32.png) [@dalegard](https://discuss.ocaml.org/u/dalegard)\ **Post date:** [December 13, 2023, 12:16pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/3 "2023-12-13T12:16:58Z")
> [@nojb](#): > > ```auto > #use "topfind";; > #require "base";; > > ``` Thanks, that works in the REPL. How would I write that in a file to be compiled by ‘ocamlopt’? (It doesn’t like the `#use` directive). ---
**Author:** ![nojb](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/nojb/32/519_2.png) [@nojb](https://discuss.ocaml.org/u/nojb)\ **Post date:** [December 13, 2023, 12:30pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/4 "2023-12-13T12:30:25Z")
> [@dalegard](#): > > Thanks, that works in the REPL. How would I write that in a file to be compiled by ‘ocamlopt’? (It doesn’t like the `#use` directive). If compiling by hand (ie without using Dune), you can do: ```auto $ ocamlfind ocamlopt -package base -linkpkg foo.ml ``` Cheers, Nicolas ---
**Author:** ![EmileTrotignon](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/emiletrotignon/32/5913_2.png) [@EmileTrotignon](https://discuss.ocaml.org/u/EmileTrotignon)\ **Post date:** [December 13, 2023, 1:09pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/5 "2023-12-13T13:09:33Z")
You should probably learn about dune in that case. ---
**Author:** ![dalegard](https://avatars.discourse-cdn.com/v4/letter/d/8dc957/32.png) [@dalegard](https://discuss.ocaml.org/u/dalegard)\ **Post date:** [December 13, 2023, 1:21pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/6 "2023-12-13T13:21:14Z")
> [@nojb](#): > > `ocamlfind ocamlopt -verbose -package base -linkpkg foo.ml` Thanks. My main reason for using Ocaml is as a back-end to Python Qt, which is graphically great, but Python itself is a ludicrously fallible language. So my compile commands look like: `ocamlopt -shared word.ml model.ml -o model.cmxs` Could I do something similar in the compile to include the packages? There is a package called ‘ocaml-in-python’ which enables Python to use these libraries, which is the perfect combination for me. ---
**Author:** ![nojb](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/nojb/32/519_2.png) [@nojb](https://discuss.ocaml.org/u/nojb)\ **Post date:** [December 13, 2023, 1:35pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/7 "2023-12-13T13:35:37Z")
> [@dalegard](#): > > `ocamlopt -shared word.ml model.ml -o model.cmxs` > > Could I do something similar in the compile to include the packages? Yes: ```auto ocamlfind ocamlopt -package base -shared word.ml model.ml -o model.cmxs ``` There is one subtetly: if `base` will be linked to the “main” program (the one loading the plugin `model.cmxs`), then the above command is OK. Otherwise, if `base` needs to be linked into the plugin itself, then you need to add `-linkpkg` to the above command line. Cheers, Nicolas ---
**Author:** ![dalegard](https://avatars.discourse-cdn.com/v4/letter/d/8dc957/32.png) [@dalegard](https://discuss.ocaml.org/u/dalegard)\ **Post date:** [December 13, 2023, 1:40pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/8 "2023-12-13T13:40:11Z")
Many thanks for your prompt and informative replies. I’ve been trying to solve this for awhile. ---
**Author:** ![amongonz](https://avatars.discourse-cdn.com/v4/letter/a/a88e4f/32.png) [@amongonz](https://discuss.ocaml.org/u/amongonz)\ **Post date:** [December 13, 2023, 6:42pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/9 "2023-12-13T18:42:51Z")
> [@dalegard](#): > > I am a F# refugee, so some of the extra work needed to get Ocaml working correctly is foreign to me. I’ve been there, OCaml toolchains do have more moving parts for dubious reasons. Assuming you’re used to .NET F# (rather than Fable), here’s how I mentally map F# tooling to OCaml: - Instead of NuGet and MSbuild, OCaml has opam and dune, except: - Packages are installed per opam “switch” instead of restored per script/project. - dune can’t just install the packages for the libraries you reference, you first need to install your dependencies separately with opam. - On the top-level (interactive/scripts), instead of referencing packages with `#r "nuget:_"`, OCaml has `#require "_"`, but to use `#require` on a bare top-level you first need to `#use "topfind";;`. Other tools can automate these directives. - If you use dune: - Instead of project files (`.fsproj`), there’re `dune` files with one or more `executable`/`library` stanzas. - `dune` files must belong to a workspace, usually a single `dune-project` file on the root of the repository. - Instead of `PackageReference`/`ProjectReference`, dune has fields like `libraries`, but again the actual packages are managed separately with opam. - However, dune can help generate `.opam` files to write your own packages and list your dependencies. - If you run the compiler directly instead, drive it with `ocamlfind` so you can resolve package references with `-package `. ---
**Author:** ![benjamin-thomas](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/benjamin-thomas/32/3966_2.png) [@benjamin-thomas](https://discuss.ocaml.org/u/benjamin-thomas)\ **Post date:** [December 13, 2023, 7:57pm UTC](https://discuss.ocaml.org/t/held-back-by-inability-to-access-libraries/13628/10 "2023-12-13T19:57:31Z")
I’ve been working on a crash course style tutorial to introduce an OCaml beginner to the the SQL library called caqti (with the help of its author) I had someone like you in mind when I wrote it, so you may find it useful. If talking to a database is something you’d need, then the tutorial should be that much more interesting. You can find the work in progress here: > **[GitHub - paurkedal/caqti-study](https://github.com/paurkedal/caqti-study)** > > Contribute to paurkedal/caqti-study development by creating an account on GitHub. The first 2 projects (hello-world and hello-tests) should give you just enough hints to get going with OCaml. Don’t hesitate to give me feedback if something didn’t quite work out