I'm trying to use the "Batteries" module, but... it doesnt work!
Here is an example:
open Batteries;;
print_endline (dump [5;4;2]);;
I'm compiling with: opam exec ocamlc main.ml the error message is:
File "main.ml", line 1, characters 5-14:
1 | open Batteries;;
^^^^^^^^^
Error: Unbound module Batteries
and the Batteries module seems installed:
$ opam install Batteries
[NOTE] Package batteries is already installed (current version is 3.0.0).
What am I missing?
Just installing a library is not enough, you have to tell the compiler that you want to link it (the compiler itself doesn't know anything about opam). There are many compilation and configuration tools available for OCaml, here's just one of the ways to build a binary that uses batteries
ocamlbuild -pkg batteries main.native
Related
My problem is similar to this, however, in my case .ocamlinit is set.
Here is my ocaml version.
mymac:Desktop myusr$ ocaml --version
The OCaml toplevel, version 4.08.1
Here is my opam version.
mymac:Desktop myusr$ opam --version
2.0.5
Here is my opam switch.
mymac:Desktop myusr$ opam switch
# switch compiler description
→ 4.08.1 ocaml-base-compiler.4.08.1 4.08.1
default ocaml-base-compiler.4.08.1 default
Here's my .ocamlinit:
mymac:Desktop myusr$ cat ~/.ocamlinit
(* ## added by OPAM user-setup for ocamltop / base ## 3ec62baf6f9c219ae06d9814069da862 ## you can edit, but keep this line *)
#use "topfind";;
(* ## end of OPAM user-setup addition for ocamltop / base ## keep this line *)
#thread;;
#require "core.top";;
#require "core.syntax";;
Here is the evidence that I already have core installed.
mymac:Desktop myusr$ opam install core utop
[NOTE] Package utop is already installed (current version is 2.4.1).
[NOTE] Package core is already installed (current version is v0.12.3).
Here is the sum.ml file from Real World OCaml:
open Core.Std
let rev read_and_accumulate accum =
let line = In_channel.input_line In_channel.stdin in
match line with
| None -> accum
| Some x -> read_and_accumulate (accum +. Float.of_string x)
let () =
printf "Total: %F\n" (read_and_accumulate 0.)
Here's what happens when I try to build it with corebuild:
mymac:Desktop myusr$ corebuild sum.native
+ ocamlfind ocamlc -c -w A-4-33-40-41-42-43-34-44 -strict-sequence -g -bin-annot -short-paths -thread -package core -ppx 'ppx-jane -as-ppx' -o sum.cmo sum.ml
File "sum.ml", line 1, characters 5-13:
1 | open Core.Std
^^^^^^^^
Error: Unbound module Core.Std
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.
Why isn't corebuild linking to the core library? How can I fix this?
The build script loads everything correctly. The module that you're trying to load no longer exists. You're trying to use an old version of the Real World OCaml book together with a very new version of OCaml and Core. The Janestreet Core library has changed a lot since those times. You should either switch to a newer book or downgrade to an older version of OCaml and Core library.
Using modern Core
Since the admission of Dune and module aliases, it is no longer needed to have an extra Std submodule, therefore Janestreet removed it (after a two-year-long deprecation). Therefore, now we're writing
open Core
instead of
open Core.Std (* no longer works *)
The same is true with Core_kernel et alas.
Since OCaml and Janesteet have moved since that time a lot, the newer version of RWO was created with updated examples. It is still a work in progress but looks quite close to be ready. So you can switch to it.
Sticking to older versions of OCaml
If you would like to use the first version of Real World OCaml, then you have to choose a version of OCaml and Janesteet's Core library which are known to be compatible. I failed to find any authoritative recommendations on which version it is better to use with the old book. So I would suggest using OCaml 4.02.3. Then you can install core as usual with opam install core (it should install version 113.33.03), and as far as I remember, it should work with the old book. If you or anyone else is having problems with this version please tell me in the comments section, and I will update this recommendation.
I've installed opam, run opam init, run opam switch 4.06.0 which created a 4.06.0 directory inside ~/.opam, run "eval opam confing env" which exports $OCAML_TOPLEVEL_PATH as ~/.opam/4.06.0/lib/toplevel amongst other things, when launching ocaml I get the dreaded:
$ ocaml
OCaml version 4.06.0
Cannot find file topfind.
Unknown directive `camlp4o'.
#
I've looked at this and this neither of which address my issue and I'm at my wits' end (first time setting up OCaml). This is my ~/.ocamlinit:
(* Added by OPAM. *)
let () =
try Topdirs.dir_directory (Sys.getenv "OCAML_TOPLEVEL_PATH")
with Not_found -> ()
;;
#use "topfind"
#camlp4o
#thread
#require "core.top"
#require "core.syntax"
EDIT: Looks like I hadn't installed core, installing core resolved that but now amongst the slew of import diagnostics I get:
Exception:
Invalid_argument
"The ocamltoplevel.cma library from compiler-libs cannot be loaded inside the OCaml toplevel".
And then a bit further down:
Raised at file "pervasives.ml", line 33, characters 25-45
Called from file "toplevel/toploop.ml", line 468, characters 4-128
Called from file "toplevel/topdirs.ml", line 144, characters 10-51
Camlp4 Parsing version 4.06.0
You should run
eval `opam config env`
Note the backticks. They are usually located to the left of the key 1 on most modern keyboards. The command should not output anything, if you see any output it means that you're running it incorrectly. You have to run this command to activate the opam installation every time you start a new shell (unless you've put this command in your shell initialization scripts, like .bashrc)
If the problem persists, then make sure, that you have installed the ocamlfind package,
opam install ocamlfind
What seemed to work for me:
make sure core is installed (opam install core)
make sure camlp4 is installed (opam install camlp4)
Insert Topfind.don't_load ["compiler-libs.toplevel"];; in-between #use "topfind";; and #require "core.top";;, as per this. It is an issue that doesn't appear to be fixed in the latest version of core (0.9.2).
I am aware of similar questions on this site but none of them have helped to solve my problem.
I am very new at OCaml and am using the following tutorial about using Camlp4 https://github.com/ocaml/camlp4/wiki/OCaml_code_generation_tutorial
However I get an error on the first line:
open Camlp4.PreCast
saying "Unbound module Camlp4"
There is a camlp4.exe file where I have downloaded OCaml so I assumed it was installed. I have tried this both on Windows 8 and Xubuntu
This is the input I am passing to the command line to compile the file:
ocamlc -o test.exe test.ml
where test.ml is the file that contains the line with the error
You should know that camlp4 is deprecated, you should use ppx instead.
If you need to compile an old programs using camlp4, they should have instructions on how to build. Anyway it's very rare to use ocamlc directly, you should try ocamlbuild or at least use ocamlfind.
In my project I have a file that uses Core.Std stuff, so I have run
opam install core
and added
open Core.Std
in my file.
When I run
ocamlbuild myprogram.native
it says:
Error: Unbound module Core
pointing to line with the open statement above.
So, I try this:
ocamlbuild -use-ocamlfind -pkgs core.std myprogram.native
and get the following message:
ocamlfind: Package `core.std' not found
So I thought that maybe I needed to run opam install core.std as well, but apparently there is no such thing according to opam. I also tried "open Core.Std;;" in the ocaml repl, but that did not work either. Any ideas?
You can either use corebuild which is usually shipped with this library or, you can try this:
ocamlbuild -use-ocamlfind -pkg core
P.S. use ocamlfind list command to view the list of available packages.
P.P.S. In addition to corebuild they usually ship coretop, a script that allows you to run core-enabled top-level. It uses utop underneath the hood, so make sure that you have installed it with opam install utop (if you're using opam), before your experiments.
Remove .std from your ocamlbuild cmd?
There seems to be conflicting information about batteries installation. I have tried several suggestions, but none have worked for me.
I first tried
ocamlfind batteries/ocaml
but that gave this error:
ocamlfind: Cannot find command: /username/godi/lib/ocaml/pkg-lib/batteries/ocaml
I then tried copying the ocamlinit file from the batteries directory to .ocamlinit in my home directory. This gave this error:
Cannot find file topfind.
File ".ocamlinit", line 38, characters 0-20:
Error: Unbound module Toploop
I am using ocaml 4.00.1.
Note: I apologize if this question is redundant with this one ocaml batteries compiling : Unbound module Toploop but the answer given was not explicit enough for me to actually try.
Like #rgrinberg said, try to install batteries with opam. For that, first download the quick installer:
$ wget http://www.ocamlpro.com/pub/opam_installer.sh
Then execute this script:
$ sh ./opam_installer.sh /usr/local/bin
It will install the latest "stable" opam (you can of course change the path /usr/local/bin) and the latest version of the OCaml compiler.
After that, you just need to run:
$ opam install batteries
and it should be ok.
You can also check ocaml.org install section (by package manager) or opam website.