ocamllex_menhir_example

OCamlLex and Menhir Example

This shows how to build a OCaml project containing a library in ./lib/ using OCamlLex and Menhir, a binary in ./bin/ that uses the library and tests of the library in ./test/ using Buck 2.

• Setup
• Buck 2 Targets
  • Examples
• Buck 2 Files

Setup

All you need to do to be able to build this project, is to install a new Opam switch and the needed packages.

In this directory ocamllex_menhir_example, run the following command to create the Opam switch and install the packages configured in the file ./third-party/dromedary.json:

Use the actual path to dromedary.py instead of just dromedary.py in the example.

python3 dromedary.py -o third-party/BUCK third-party/dromedary.json

Then, the Opam switch's environment must be activated:

opam switch ./third-party
eval $(opam env --switch=./third-party --set-switch)

Now all needed packages should be installed and set up, so you can build and run the executable:

buck2 run //:bin

and the tests:

buck2 run //:test

Buck 2 Targets

• buck2 clean - deletes all generated files (in the directory ./buck-out/v2/).
• buck2 targets //... - lists all available targets, including all Opam packages. The packages have a prefix of root//third-party.
• buck2 build //... - builds all targets.
• buck2 run //:bin - run the generated executable. This is an alias for buck2 run //bin:ocamllex_menhir_example.
• buck2 run //:test - run the generated executable. This is an alias for buck2 run //test:ocamllex_menhir_example.

Examples

List only the targets of ocamllex_menhir_example, without the Opam packages:

> buck2 targets //lib: //bin: //test: //:
File changed: root//README.md
Build ID: 58742ba4-60db-418a-9d02-1439c7e4112f
Jobs completed: 2. Time elapsed: 0.0s.
root//:bin
root//:lib
root//:test
root//bin:ocamllex_menhir_example
root//lib:ocamllex_menhir_example
root//lib:ocamllex_menhir_example.mli
root//lib:ocamllex_menhir_example__
root//test:ocamllex_menhir_example

Run the generated executable:

> buck2 run //:bin
File changed: root//README.md
Build ID: 4ff6fa61-4b10-4744-8d88-583a7894fd90
Jobs completed: 3. Time elapsed: 0.0s.
BUILD SUCCEEDED
Some examples:
1 + 2 * 5 = 11
1.486 - 2.5 / 0.123 = -18.839203252
let a = 5 in a / 3 = 1
let a = 4.0 - 5.2 in let b = a * 0.123 in let c = 5.6 in a + b + c = 4.2524

Run the tests:

>  buck2 run //:test
File changed: root//README.md
Build ID: 3d781d47-672c-4f79-9810-13042b8641d2
Jobs completed: 3. Time elapsed: 0.0s.
BUILD SUCCEEDED
qcheck random seed: 896189154
Testing `Interpreter Tests'.
This run has ID `WNG915K9'.

  [OK]          Fixed terms and results          0   1 - 1 = 0.
  [OK]          Fixed terms and results          1   2.0 * 1.75 - 4.5 = -1.0.
  [OK]          Fixed terms and results          2   let a = 5.21 in a - 0.21 = 5.0.
  [OK]          Generated Terms                  0   n - m.
  [OK]          Generated Terms                  1   n + m.
  [OK]          Generated Terms                  2   n * m.
  [OK]          Generated Terms                  3   n / m.

Full test results in `./OCaml-Buck-2-Examples/ocamllex_menhir_example/_build/_tests/Interpreter Tests'.
Test Successful in 0.002s. 7 tests run.

Buck 2 Files

• ./.buckroot - this marks the directory as the root of the Buck 2 directories. In real examples you might want to put all your projects in subdirectories of the Buck 2 root directory. This is an empty file.

• ./.buckconfig - Contains the configuration generated by buck2 init --git. Set the execution platform to the default one of the prelude.

  [build]
  execution_platforms = prelude//platforms:default

• ./toolchains/BUCK - The configuration of the toolchains to use. You always need C++ (system_cxx_toolchain) and Python (system_python_bootstrap_toolchain). The OCaml tool chain is system_ocaml_toolchain.

• ./third-party/ - This directory contains all third party dependencies and their configuration, like Opam packages. In a bigger Buck 2 configuration you want to use one subdirectory for each language or for each project, e.g. third-party/ocaml for all OCaml project dependencies or third-party/ocamllex_menhir_example for the dependencies of ocamllex_menhir_example, if for example Opam package versions differ from project to project.

• ./third-party/dromedary.json - This is the configuration of the Opam switch to create and the packages to install.

• ./third-party/BUCK - The configuration of the Opam packages. Generated by the ocaml-script dromedary.py, and should not be edited manually.

• ./BUCK - The main Buck 2 configuration file. Contains shorter aliases for the bin and test targets.

• ./bin/BUCK - The rules to build the binary.

• ./lib/BUCK - The rules to build the library.

• ./test/BUCK - The rules to build the test.

• ./prelude/ - Contains all toolchains and rules for all supported languages of Buck 2. A Git submodule.

• ./.merlin - Merlin configuration file for Merlin and the OCaml-LSP