Erlang/Elixir NIFs for nim

wltsmrz · October 28, 2019, 7:02am

Fairly complete NIF API bindings for nim: https://github.com/wltsmrz/nimler

Actively working on making it more nim-idiomatic, but it likely won’t end up with extreme convenience like embedding nim source within an Elixir module, etc… Possibly suited to use cases like Nerves. nim’s owned refs / “newruntime” will likely end up being especially beneficial to this end. Currently–until newruntime is complete–it looks like avoiding allocations (or allocating with enif_alloc() ?) and avoiding nim refs (traced pointers) are reasonable constraints. Of course, nim’s GC can also be entirely disabled.

Feedback and collaboration welcomed.

Eiji · October 28, 2019, 7:06am

Hi, I found one typo.

Here is @on_load:

github.com

wltsmrz/nimler/blob/master/docs/CREATE_NIF.md#3-wrap-nif-library-in-a-module

# Creating a NIF

This example will create a NIF for adding two signed 32-bit integers. See [docs/GLOSSARY](GLOSSARY.md) for unknown terms.

### 1. Write NIF in nim

```nim
# nif.nim
import nimler

proc add_numbers(env: ptr ErlNifEnv, argc: cint, argv: ErlNifArgs): ErlNifTerm =
    let a1 = argv[0].decode(env, int32).get(0)
    let a2 = argv[1].decode(env, int32).get(0)
    let r = a1 + a2
    return r.encode(env)

export_nifs("Elixir.NumberAdder", @[
  ("add_numbers", 2, add_numbers)
])
```

This file has been truncated. show original

but in example is @onload:

github.com

wltsmrz/nimler/blob/master/example/NumberAdder.ex


defmodule NumberAdder do
    @onload :load_nif

    def add_numbers(_a, _b), do: raise "not implemented"

    def load_nif, do
        :erlang.load_nif(to_charlist(Path.join(Path.dirname(__ENV__.file), "nif")), 0)
        IO.inspect(add_numbers(1, 2))
    end
end

Paradox · January 11, 2020, 4:45am

Amusingly, I was talking to a friend about this the other day. Even came up with the name nimler.

Happy to see someone else has already done the work, and even happier to finally be able to write some NIFs in something that isn’t Rust or C.

wltsmrz · February 3, 2020, 11:30pm

Haha, yeah, the naming was kind of predictable.

Update: nim devel has a new reference-counting GC. The nimler tests now run with --gc:arc, and it actually seems like a huge win for this use case.