I have installed the OCaml CSV module in C:\OCaml\lib. When I run the following code in the top level open Csv;;
I receive the error message Error: Unbound module Csv
I am not sure why the module is not loading.
Thanks
There are two steps involved. First you need to make sure that CSV loaded into your toplevel, then you can open it. I don't use windows, but under OS X it looks like this:
$ ocaml
OCaml version 4.00.1
# #load "unix.cma";;
# open Unix;;
# stat;;
- : string -> Unix.stats = <fun>
#
I just found the solution. I did not compile the csv.ml and csv.mli files.
If anybody else has this problem here are the steps to fix the problem:
1) In the command line go to the OCaml\lib directory where your .ml and .mli files are located
2) Run the commands ocamlc -c modulename.mli and ocamlc -c modulename.ml
in the toplevel you can now run open modulename;;
Related
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
i'm having a problem while trying to compile an ocaml file with ocamlc -o hello hello.ml it gives me this error
Error: Unbound module Core
which is weird because when i use utop and import the core std with open Core.Std;; it does work and import it, any ideas of how to solve this problem ?
Thanks in advance
open Core.Std does not really import core, it just puts its values in scope so that you can refer to Core.Std.x as just x.
To import it you need to pass it to require the package somehow in your compiler. The easiest way is to use ocamlfind:
ocamlfind ocamlc -package core -linkpkg -o hello hello.ml
The corresponding way to do that in utop is by passing -require core on the command line or #require "core" in the REPL.
When I attempt to load the file extLib.cma in utop, OCaml's top level, I get the following error:
Cannot find file extLib.cma
However, if I try to install it using opam I get the following note:
Package extlib is already installed.
What am I doing wrong?
If your purpose is to interactively use some of extLib's functions then
$ utop
μ> #require "extlib";;
μ> ExtString.String.explode "ExtLib";;
- : char list = [E; x; t; L; i; b]
If it's something else, then you may need to specify the exact path to extLib.cma, and something similar to the following should work:
$ utop
μ> #load "/Users/xxx/.opam/4.02.3/lib/extlib/extLib.cma";;
where /Users/xxx is your home directory/folder; 4.02.3 is my current compiler version, set via opam switch (IIRC, it's system by default).
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.
I am trying to follow along with Real World OCaml by setting up opam, utop, and the Core modules as well. I've followed these directions with some success. In particular, when I run utop without specifying the file to load, I can load Core with no issues:
[dswain#Dupree scratch]$ utop
Welcome to utop version 1.12 (using OCaml version 4.01.0)!
Findlib has been successfully loaded. Additional directives:
...
utop # open Core;;
utop #
So far so good. Now if I attempt to load a script from the command line with the same code:
[dswain#Dupree scratch]$ cat test.ml
open Core.Std;;
[dswain#Dupree scratch]$ utop test.ml
File "test.ml", line 1, characters 0-13:
Error: Unbound module Core
[dswain#Dupree scratch]$
I assume this is a configuration mistake I've made somewhere, but I'm not quite sure where.
Setup details
I've attempted to reinstall ocaml, opam, utop, and core to no avail. I've got the following config changes that I'm aware that opam init made during setup:
~/.ocamlinit:
#use "topfind";;
#thread;;
#camlp4o;;
#require "core.top";;
#require "core.syntax";;
~/.bash_profile
# OPAM configuration
. /home/dswain/.opam/opam-init/init.sh > /dev/null 2> /dev/null || true
eval `opam config env`
I'm running Arch Linux, and followed the steps to install opam via the AUR with no issues I'm aware of. I was also able to build & install all of the packages from the installation instructions without any errors I know of.
This is because utop executes a script-file before it runs .ocamlinit file. I'm not sure whether it is a bug or a feature, but that is how the code is written. Indeed, most users runs utop from emacs and send pieces of code to utop with C-c C-s.
If you're not comfortable with emacs, I can suggest to use the following workflow:
start utop
do some coding in your favorite editor
load code in utop with #use "your_file.ml";;
play with it, if not satisfied goto 2.