wasm_interp: simplified ImportDispatcher

We don't really need a trait for the 'import module' concept.

crates/wasm_interp/src/lib.rs

@@ -2,9 +2,25 @@ mod call_stack;
 mod instance;
 pub mod test_utils;
 mod value_stack;
-mod wasi;
+pub mod wasi;
+
+// Main external interface
+pub use instance::Instance;
 
 // Exposed for testing only. Should eventually become private.
 pub use call_stack::CallStack;
-pub use instance::{Action, Instance};
+pub use instance::Action;
 pub use value_stack::ValueStack;
+
+use roc_wasm_module::Value;
+
+pub trait ImportDispatcher {
+    /// Dispatch a call from WebAssembly to your own code, based on module and function name.
+    fn dispatch(
+        &mut self,
+        module_name: &str,
+        function_name: &str,
+        arguments: &[Value],
+        memory: &mut [u8],
+    ) -> Option<Value>;
+}

crates/wasm_interp/src/wasi.rs

@@ -1,41 +1,8 @@
 use roc_wasm_module::Value;
 
-pub trait ImportDispatcher {
+pub const MODULE_NAME: &'static str = "wasi_snapshot_preview1";
-    /// Dispatch a call from WebAssembly to your own code, based on module and function name.
-    /// The call arguments are passed in, along with a mutable pointer to WebAssembly memory.
-    fn dispatch(
-        &mut self,
-        module_name: &str,
-        function_name: &str,
-        arguments: &[Value],
-        memory: &mut [u8],
-    ) -> Option<Value>;
-}
 
-pub trait ImportDispatcherModule {
+pub fn dispatch(function_name: &str, arguments: &[Value], _memory: &mut [u8]) -> Option<Value> {
-    const NAME: &'static str;
-
-    /// Dispatch a call from WebAssembly to your own code, based on the function name.
-    /// The call arguments are passed in, along with a mutable pointer to WebAssembly memory.
-    fn dispatch(
-        &mut self,
-        function_name: &str,
-        arguments: &[Value],
-        memory: &mut [u8],
-    ) -> Option<Value>;
-}
-
-pub struct WasiDispatcher {}
-
-impl ImportDispatcherModule for WasiDispatcher {
-    const NAME: &'static str = "wasi_snapshot_preview1";
-
-    fn dispatch(
-        &mut self,
-        function_name: &str,
-        arguments: &[Value],
-        _memory: &mut [u8],
-    ) -> Option<Value> {
     match function_name {
         "args_get" => todo!("WASI {}({:?})", function_name, arguments),
         "args_sizes_get" => todo!("WASI {}({:?})", function_name, arguments),
@@ -84,5 +51,4 @@ impl ImportDispatcherModule for WasiDispatcher {
         "sock_shutdown" => todo!("WASI {}({:?})", function_name, arguments),
         _ => panic!("Unknown WASI function {}({:?})", function_name, arguments),
     }
-    }
 }