From this SO question: List Comprehension in Ocaml?, I could install the comprehension package with opam install pa_comprehension, and use the package in toplevel REPL.
# #require "pa_comprehension";;
# open Batteries;;
# [? 2 * x | x <- 0 -- max_int ; x * x > 3 ?];;
- : int Batteries.Enum.t = <abstr>
Then, how can I compile the code?
Unfortunately, since pa_comprehension package name is not ended with .syntax extension, this is a little bit harder than it should be. (The fact that this issue is still not fixed, shows that using pa_comprehension is not very popular in modern OCaml). So, without the proper extension, we need to do everything manually. If your file is named pr.ml, then the correct invocation is:
$ ocamlbuild -use-ocamlfind -syntax camlp4o -pkg camlp4,pa_comprehension pr.native
If you don't wan't to type it every time, then you can create _tags file, with the following contents:
$ cat _tags
<**/*> : package(camlp4),syntax(camlp4o),package(pa_comprehension)
In that case, the command line spell is a little bit easier:
$ ocamlbuild -use-ocamlfind pr.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 am trying to compile a ocaml program (part of it shown below)
open Ocamlbuild_plugin
open Command
(** helper functions )
( splitting strings using a delimeter character *)
let rec strsplit sep str accu len =
try let idx = String.rindex_from str (len - 1) sep in
strsplit sep str ((String.sub str (idx + 1) (len - 1 - idx)) :: accu) idx
with Not_found -> (String.sub str 0 len) :: accu
let strsplit sep str = strsplit sep str [] (String.length str)
(** initializing variables from the environment *)
let host = Ocamlbuild_pack.Ocamlbuild_Myocamlbuild_config.system
the last line is causing unbound module error. What can i do? thanks
update 1:
The code is from a github project https://github.com/ykazakov/cb-reasoner
And i am following an instruction there to use "make" to compile the program .. this make file looks like this
BUILDDIR ?= _build
OCAMLBUILD ?= ocamlbuild
OCAMLBUILD := $(OCAMLBUILD) -build-dir $(BUILDDIR)
.PHONY: main clean clib
main:
$(OCAMLBUILD) main/cb.native
all:
$(OCAMLBUILD) main/cb.native jni cwrap/libcb.a
cwrap:
$(OCAMLBUILD) cwrap/libcb.a
jni:
$(OCAMLBUILD) jni
clean:
$(OCAMLBUILD) -clean;\
rm -f cb.native
I answered this question on the ocamlbuild issue tracker (I follow StackOverflow but less closely, sorry). Quoting below for convenience:
OCamlbuild exports a stable interface for plugin users as the Ocamlbuild_plugin module. Using Ocamlbuild_pack directly accesses ocamlbuild's internal definitions, and is recommended against as there are no guarantees of backward-compatibility.
In your specific case, a module is used by this code that indeed was removed in more recent ocamlbuild versions (its presence was an artifact of the specific way ocamlbuild's build system was integrated into the compiler distribution). I could correctly build this software with OCaml 3.12.1, 4.00.1 and 4.01.0, but not any more recent version of OCaml and ocamlbuild.
Using opam makes it easy to install old OCaml versions:
opam install 4.01.0
eval $(opam env --switch=4.01.0)
make # if in the project's directoyr
If you are interested in patching this software to make it compatible with more recent OCaml versions, we could discuss how to get the corresponding information in a more robust way.
In any case, I'm closing this as it is not a problem of ocamlbuild, but rather a maintenance question for cb-reasoner. (Of course, feel free to post further comments.)
I was messing around with the OCaml FFI to try to figure out how it goes about inferring the width of a C enum (which I think is implementation-defined for C) and am trying to insert a type of the wrong width to see what blows up at runtime. That's the motivation, but the actual issue I ran into is much more mundane.
I have a simple OCaml file that uses the C FFI to call a trivial function in example.c that converts an enum to an int.
open Printf;;
let (#->) = Ctypes.(#->);;
let returning = Ctypes.returning;;
let foreign = Foreign.foreign;;
(* deliberately use the wrong scalar type for argument *)
let wrong_int64_of_color =
foreign "int_of_color" (Ctypes.int64_t #-> returning Ctypes.int64_t);;
let main () =
printf "%Ld\n" (wrong_int64_of_color (Int64.of_int 100));;
let () = main ();;
I configured opam and installed Ctypes and Ctypes.Foreign
% opam config env | sed -e 's/=.*/=/'
CAML_LD_LIBRARY_PATH=
OPAMUTF8MSGS=
MANPATH=
PERL5LIB=
OCAML_TOPLEVEL_PATH=
PATH=
% opam list | grep ctypes
ctypes 0.6.2 Combinators for binding to C libraries withou
ctypes-foreign 0.4.0 Virtual package for enabling the ctypes.forei
The two usual incantations I use for compiling a simple .ml script have both failed me and I'm out of ideas. ocamlfind and corebuild (which I think is a wrapper on top of ocamlbuild)
ocamlfind can't seem to find ctypes and foreign. However, it doesn't complain that about not being able to locate the packages so I'm guessing ctypes and ctypes.foreign are the correct names for these packages in the weird findlib namespace.
% ocamlfind ocamlopt -package findlib,ctypes,ctypes.foreign -thread call_example.ml
File "_none_", line 1:
Warning 58: no cmx file was found in path for module Foreign, and its interface was not compiled with -opaque
File "call_example.ml", line 1:
Error: No implementations provided for the following modules:
Ctypes referenced from call_example.cmx
Foreign referenced from call_example.cmx
Why can't ocamlfind locate these modules? I have no problem loading them into the toplevel.
─( 22:30:42 )─< command 0
utop # #require "ctypes";;
─( 22:30:42 )─< command 1
utop # open Ctypes;;
─( 22:30:55 )─< command 2
utop # #require "ctypes.foreign";;
─( 22:31:00 )─< command 3
utop # open Ctypes;;
It seems to me that you forget to add -linkpkg ocamlfind option to instruct the compiler actually link the libraries from the packages to build the executable.
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 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;;