Add an example of a plugin using WASI

.github/workflows/ci.yml

@@ -30,3 +30,4 @@ jobs:
       - name: Build and test
         run: |
           nix flake check --all-systems --eval-cores 0 -L
+          nix flake check ./wasi --all-systems --eval-cores 0 -L

.gitignore

@@ -3,3 +3,4 @@ result
 /target/
 *~
 /*/tests/*.out
+/wasi/target/

nix-wasm-plugin-fib/Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [lib]
-crate-type = ["cdylib"]
+crate-type = ["lib", "cdylib"]
 
 [dependencies]
 nix-wasm-rust = { path = "../nix-wasm-rust" }

nix-wasm-rust/src/lib.rs

@@ -50,6 +50,10 @@ pub enum Type {
 }
 
 impl Value {
+    pub fn from_id(id: ValueId) -> Value {
+        Value(id)
+    }
+
     pub fn get_type(&self) -> Type {
         extern "C" {
             fn get_type(value: ValueId) -> Type;
@@ -284,4 +288,11 @@ impl Value {
             }
         }
     }
+
+    pub fn return_to_nix(&self) -> ! {
+        extern "C" {
+            fn return_to_nix(value: ValueId) -> !;
+        }
+        unsafe { return_to_nix(self.0) }
+    }
 }

wasi/Cargo.toml

@@ -0,0 +1,9 @@
+[workspace]
+members = [
+    "nix-wasi-plugin-fib",
+]
+resolver = "2"
+
+[profile.release]
+lto = true
+opt-level = 'z'