wasm-minimal-protocol for

A no-longer-minimal protocol to write typst plugins, featured with:

• auto bi-convert between typst and Nim types like float, string and tables
• support default arguments and varargs
• ability to export existing function to typst, via export_typst_from
• reserving doc from Nim to typst, means no need to write document twice (turn off via compile flag -d:exportNimDocToTypst=off)
• alternative cbor engine to choose, via -d:cborious [^cborious]
• Fine-grained control over exported name, serialization & deserialization (ref datetime-parse example)

[^cborious]: requires manually installation like nimble install cborious

You want to write a plugin

For other languages like Rust, ref https://github.com/astrale-sharp/wasm-minimal-protocol, which is however really minimal (lacks features above).

Nim plugins can use this repo to automatically implement the protocol with a macro:

# Nim file
# /path/to/plugin.nim
import pkg/wasm_minmal_protocol

import std/[math, strutils]
from std/sugar import `->`

# used as `{.exportc.}`
func mew(n: int): string{.export_typst.} =
  "mew~".repeat n

export_typst_from_func spaces
export_typst_from_func fac, "factorial"
export_typst_from_func formatSize, ncTypst  # use typst name convention

# overloaded functions must be specified with a signature:
export_typst_from_func cbrt, (float) -> float
export_typst_from_func format, "str-format", (string, varargs[string]) -> string
export_typst_from_func strCount, "str-count", (string, string) -> string
# or `export_typst_from fac` to export as `fac`

compile using the binary this package provide, nim-typst-plugin (available if install via nimble install, or after nimble build, it'll be in ./bin/ directory)

nim-typst-plugin -d:gen_typst /path/to/plugin.nim

Note this reply on your Nim installation and [wasi-stub][wasi-stub] (see below)

-d:gen_typst to also generate .typ file for handy use, other than bare .wasm

Then write:

// Typst file
#import "/path/to/plugin.typ": *
// no need to call cbor
#assert.eq(2.0, cbrt(8.0))
#str-format("$1 $2 was somehow translated literally", "violet", "evergarden")
#str-format("$# and $# refer to each", "spice", "wolf")
#assert.eq(str-count("litlighilit", "i"), 4)
#factorial(3)

You should also take a look at this repository's examples.