Coswitches
Switches & Coswitches
An OPAM switch is a version of the OCaml toolchain together with a collection of OPAM packages compiled with that toolchain.
An OBazl coswitch is a collection of symlinks and Bazel files that serve to integrate an OPAM switch into the Bazel ecosystem.
OPAM switches are located in an OPAM installation; the default
location is $HOME/.opam, but users can initialize an OPAM
installation in any directory. Coswitches are located in their own
directories, outside of any OPAM installation. They have the following
structure:
Shared coswitches
The here coswitch
here switches are no longer supported. Use a local switch instead.
|
Troubleshooting
here-switches are not copyable - if you copy a project to a different
name, you must delete .opam and .obazl.d and recreate. This is
because the location of the toolchain is hardcoded into the toolchain
when it is built. For example, browse lib/ocaml/camlheader of any
toolhchain installation.
If you create a here coswitch using an OPAM "sys" switch you may run
into trouble. An OPAM sys switch is a switch you’ve installed in your
system, e.g. in /usr/local/bin and /usr/local/lib. In that case,
if you have the same compiler version installed in OPAM, you’ll get
something like the following when youu run opam switch
list-available. The fix is
bazel run @ocaml//here:install -- ocaml-base-compiler
$ opam switch list-available # Listing available compilers from repositories: default # Name # Version # Synopsis ocaml-option-32bit 1 Set OCaml to be compiled in 32-bit mode for 64-bit Linux and OS X hosts ... ocaml-base-compiler 4.12.0~rc1 First release candidate of OCaml 4.12.0 ocaml-variants 4.12.0~rc1+options First release candidate of OCaml 4.12.0 ocaml-base-compiler <1> 4.12.0 Official release 4.12.0 ocaml-system <2> 4.12.0 The OCaml compiler (system version, from outside of opam) ocaml-variants 4.12.0+domains OCaml 4.12.0, with support for multicore domains ...
| 1 | version 4.12.0 is available |
| 2 | it is also installed in the local system |
Action: @opam//here/install — -h
$ bazel run @opam//here/init -- -h
...
Usage: bazel run @opam//here/init -- [args]
args:
-c compiler version
-s switch name
-x dry-run
-d debug
-v verbose
Default: uses compiler version listed in .obazl.d/here.compiler
if found; otherwise prompts user.
case 1:
Initial conditions: @opam//here/init has been run
$ bazel run @opam//here/status ...
Action: install
$ bazel run @opam//here/install -- -p ounit2 ... Begining OPAM processor output: The following actions will be performed: ∗ install seq base [required by ounit2] ∗ install ocamlfind 1.9.3 [required by base-bytes] ∗ install dune 3.0.3 [required by ounit2] ∗ install base-bytes base [required by ounit2] ∗ install stdlib-shims 0.3.0 [required by ounit2] ∗ install ounit2 2.2.6 ===== ∗ 6 ===== <><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><> 🐫 ⬇ retrieved ounit2.2.2.6 (https://opam.ocaml.org/cache) ∗ installed seq.base ⬇ retrieved ocamlfind.1.9.3 (https://opam.ocaml.org/cache) ⬇ retrieved stdlib-shims.0.3.0 (https://opam.ocaml.org/cache) ⬇ retrieved dune.3.0.3 (https://opam.ocaml.org/cache) ∗ installed ocamlfind.1.9.3 ∗ installed base-bytes.base ∗ installed dune.3.0.3 ∗ installed stdlib-shims.0.3.0 ∗ installed ounit2.2.2.6 Done.
Post-install status
<projroot>$ bazel run @opam//here/status ... @opam//here/status root: .opam switch: here Begining OPAM processor output: prefix <projroot>/.opam/here lib <projroot>/.opam/here/lib bin <projroot>/.opam/here/bin sbin <projroot>/.opam/here/sbin share <projroot>/.opam/here/share doc <projroot>/.opam/here/doc etc <projroot>/.opam/here/etc man <projroot>/.opam/here/man toplevel <projroot>/.opam/here/lib/toplevel stublibs <projroot>/.opam/here/lib/stublibs user <user id> group <grp name> Begining OPAM processor output: # Packages matching: installed # Name # Version base-bigarray base base-bytes base base-threads base base-unix base dune 3.0.3 ocaml 4.13.0 ocaml-base-compiler 4.13.0 ocaml-config 2 ocaml-options-vanilla 1 ocamlfind 1.9.3 ounit2 2.2.6 seq base stdlib-shims 0.3.0 WORKSPACEs: toolchain: .obazl.d/opam/here/ocaml stublibs bin WORKSPACE.bazel bigarray compiler-libs unix threads str c_api toolchains dynlink
Action: config
$ bazel run @opam//here/config ... Begining OPAM processor output: The following actions will be performed: ∗ install seq base [required by ounit2] ∗ install ocamlfind 1.9.3 [required by base-bytes] ∗ install dune 3.0.3 [required by ounit2] ∗ install base-bytes base [required by ounit2] ∗ install stdlib-shims 0.3.0 [required by ounit2] ∗ install ounit2 2.2.6 ===== ∗ 6 ===== <><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><> 🐫 ⬇ retrieved ounit2.2.2.6 (https://opam.ocaml.org/cache) ∗ installed seq.base ⬇ retrieved ocamlfind.1.9.3 (https://opam.ocaml.org/cache) ⬇ retrieved stdlib-shims.0.3.0 (https://opam.ocaml.org/cache) ⬇ retrieved dune.3.0.3 (https://opam.ocaml.org/cache) ∗ installed ocamlfind.1.9.3 ∗ installed base-bytes.base ∗ installed dune.3.0.3 ∗ installed stdlib-shims.0.3.0 ∗ installed ounit2.2.2.6 Done.
case 4: prior installation
Initial conditions
<projroot> $ bazel run @opam//here/status ... @opam//here/status root: .opam switch: here Begining OPAM processor output: prefix <projroot>/.opam/here lib <projroot>/.opam/here/lib bin <projroot>/.opam/here/bin sbin <projroot>/.opam/here/sbin share <projroot>/.opam/here/share doc <projroot>/.opam/here/doc etc <projroot>/.opam/here/etc man <projroot>/.opam/here/man toplevel <projroot>/.opam/here/lib/toplevel stublibs <projroot>/.opam/here/lib/stublibs user <user id> group <grp name> Begining OPAM processor output: # Packages matching: installed # Name # Version base-bigarray base base-threads base base-unix base ocaml 4.13.0 ocaml-base-compiler 4.13.0 ...
Action: $ bazel run @opam//here/init
<projroot> $ bazel run @opam//here/init
OPAM here-switch already configured at root ./.opam, switch 'here', compiler: '4.13.0'.
Replace? [yN] N
cancelling here-switch init
<projroot> $ bazel run @opam//here/init
OPAM here-switch already configured at root ./.opam, switch 'here', compiler: '4.13.0'.
Replace? [yN] y
removing ./.opam
Your here switch is configured to use compiler version: 4.13.0 (specified in .obazl.d/opam/here.compiler)
Reconfigure using with same version? (if no, you will be prompted for a different version)
[Yn] n
Current OPAM switch name is '4.13.0', configured with compiler version 4.13.0
Configure here-switch with compiler version 4.13.0? [Yn] n
Which compiler version do you want to install? (<enter> to cancel) 4.11.0
Begining OPAM processor output:
No configuration file found, using built-in defaults.
<><> Fetching repository information ><><><><><><><><><><><><><><><><><><><>
[default] Initialised
Begining OPAM processor output:
<><> Installing new switch packages <><><><><><><><><><><><><><><><><><><><> 🐫
Switch invariant: ["ocaml-base-compiler" {= "4.11.0"} | "ocaml-system" {= "4.11.0"}]
<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><> 🐫
∗ installed base-bigarray.base
∗ installed base-threads.base
∗ installed base-unix.base
⬇ retrieved ocaml-base-compiler.4.11.0 (https://opam.ocaml.org/cache)
∗ installed ocaml-base-compiler.4.11.0
∗ installed ocaml-config.1
∗ installed ocaml.4.11.0
Done.
Postcondition status
$ bazel run @opam//here/status ... @opam//here/status root: .opam switch: here Begining OPAM processor output: prefix <projroot>/.opam/here lib <projroot>/.opam/here/lib bin <projroot>/.opam/here/bin sbin <projroot>/.opam/here/sbin share <projroot>/.opam/here/share doc <projroot>/.opam/here/doc etc <projroot>/.opam/here/etc man <projroot>/.opam/here/man toplevel <projroot>/.opam/here/lib/toplevel stublibs <projroot>/.opam/here/lib/stublibs user <user id> group <grp name> Begining OPAM processor output: # Packages matching: installed # Name # Version base-bigarray base base-threads base base-unix base ocaml 4.11.0 ocaml-base-compiler 4.11.0 ocaml-config 1