A note to self on using OCaml
with the ReasonML
syntax without Bucklescript
.
Setup
- Install opam
- Install
reason
language options withopam install reason
HelloWorld
Create a hello.re
file:
// hello.re
print_string("Hello world!\n");
Compile hello.re
by running ocamlc -o hello -pp "refmt -p ml" -impl hello.re
.
Open your terminal and run ./hello
.
Your output is:
➜ helloworld ocamlc -o hello -pp "refmt -p ml" -impl hello.re
➜ helloworld ./hello
Hello world!
Sources
https://riptutorial.com/ocaml/example/7096/hello-world
Notes from Discord Channel:
@idkjs the ocaml toolchain read only ocaml syntax, binary ast (which is shared between reason/ocaml). Hopefully the reason package come with a tool that is able to translate both syntax refmt.
the -p option of refmt is print. So refmt -p ml hello.re > hello.re.ml take the reason syntax in the re file and output in the hello.re.ml file. I use -p ml for debugging but -p binary is used by dune because it is quicker. Then you can use OCaml binary ocamlc -o my_target hello.re.ml (the -o is for ouput default name is machine dependant). because file end with .ml the compiler know it must build .cmo/.exe, if passed a .mli it will build .cmi, etc. The problem with .re file is it is not .ml nor .mli so we need to say it will be a implementation -impl or a interface -intf. and finally -pp is run this command on this file to have a valid ocaml file (here we use refmt because it output valid OCaml)
-impl <file> Compile <file> as a .ml file
-intf <file> Compile <file> as a .mli file
-intf-suffix <string> Suffix for interface files (default: .mli)
-pp <command> Pipe sources through preprocessor <command>
Top comments (2)
If you had asked me before yesterday, I would not have been aware of it. Thank you for making the point, brother.
Incidentally, can you recommend some F# sharp starting material? I need to get my feet wet there.
All about esy brother. Those dudes are ocaml/npm alchemists. The issue was trying to understand how to do it without esy. If you want to see it with esy check out github.com/idkjs/esy-nantes-tutorial. It does the same exact thing using esy. The readme tells you how to do it.