rontolisp.wit/import

(import "path.wit" options) with [rontolisp.wit :as wit]

Reads the WIT file -- relative to the file naming it -- and binds the functions of one of its interfaces as the vars of a namespace of their own (WIT contracts). The options map:

• :interface -- the interface: its full id ("wasi:keyvalue/store@0.2.0"), the id without its version, or its bare name when the file defines it once. Required.
• :as -- an alias for the interface's namespace in the current one.
• :refer -- a vector of member names to refer, or :all. One of :as and :refer is required: nothing else reaches the vars.
• :from -- the import module of a WASM core module; the interface's bare name by default.
• :field-style -- :camel (the default: create-shader imports createShader) or :kebab (the label as written), for a WASM core module's import fields.

A function is the var of its WIT name; a resource's method takes the handle first and is prefixed with the resource (bucket.get is kv/bucket-get), its constructor is <resource>-new, and its release <resource>-drop. The vars are functions like a defn's: #'kv/open prints #'wasi:keyvalue.store@0.2.0/open (the namespace is the interface's id), and (map kv/bucket-get ...) takes one. The import binds the interface once per program; a second one only wires its alias and refers.

$ cat math.wit
package example:host@0.1.0;

interface math {
  add-ints: func(a: s32, b: s32) -> s32;
  is-even: func(n: s32) -> bool;
}
$ cat app.clj
(ns app (:require [rontolisp.wit :as wit]))

(wit/import "math.wit" {:interface "example:host/math" :as math :refer [is-even]})

(defn report {:wasm/export {:params [:int] :returns :string}} [n]
  (str (math/add-ints n 1) " " (is-even n)))
$ rontolisp app.clj -o app.wasm --no-wasi --emit-js-glue

The calls lower to the WIT's own bindings on each target: the provider on the interpreter and the JVM (provide), one math.addInts / math.isEven host import of a WASM core module, a canonical-ABI import under --component; a core module imports the members the program calls. Each value crosses in its Clojure spelling -- a record as a map, a variant's case as a keyword or [:case payload] -- and a result's error arm throws an ExceptionInfo holding the error value (What crosses). A member whose types reach a stream or a future, or an async func, is not bound, and a reference to it is refused naming its WIT line.