title	published	description	tags	series
Luv + ReasonML, the Straight Dune Build	false	Debugging the build system	reason, dune, ocaml, esy, spin	ReasonML, Dune, Pesy and Spin

I am trying to use the aantron/luv library to try to build something and I ran into all kinds of build system issues mostly because I still haven't grokked the reason-native build system yet. That's ok. This note is my way of getting better and having a reference I understand when I need to come back to it. The reason-native build environment has a list of great tools you can use. Most prominent among them are Dune, Esy/Pesy and Spin. The last two use dune so you end up learning about dune whatever you do.

Let's start with dune. Assuming you have opam and dune installed this is easy. Go here if you don't then head back.

Make a directory and cd into it.

mkdir straight-dune-luv && cd straight-dune-luv

Add a .gitignore file for ocaml using the gitignore-cli.

gi ocaml > .gitignore

Create a switch with ocaml 4.08.1. luv requires at least that.

opam switch create . ocaml-base-compiler.4.08.1

Add reason and luv. dune will tell you nicely if you forget to do this.

opam install reason luv

Create you dune file and run install.

touch dune && dune install

Create a Makefile, optional. I just copied the one from a previous post here.

touch Makefile

Which didn't work because of the tabs being off from the paste. Ran cat -e -t -v Makefile which I found on stackoverflow.

Add the code from aantron/luv/example/progress.ml.

touch progress.ml

Convert it to .re and delete the .ml version.

bsrefmt --parse ml progress.ml --print re > progress.re
rm progress.ml

Run make to build it.

make

Run progress.exe.

dune exec ./progress.exe

Output:

❯ dune exec ./progress.exe
33%                  
66%
Done

Honestly, that was very easy. This has to be your go to build for a simple project.

Let's try with Pesy next.

mkdir straight-ocaml-luv && cd straight-ocaml-luv
opam install reason luv
opam switch create . ocaml-base-compiler.4.08.1
touch dune && dune install
touch Makefile
touch progress.ml
bsrefmt --parse ml progress.ml --print re
dune
cat -e -t -v Makefile
dune build @install
make
dune exec ./progress.exe