Fix disco_datadir variable not recognized after wizer

Author: HeinrichApfelmus

src/Eval.hs

@@ -46,13 +46,10 @@ resolveModule' = resolveModule
 
 initDisco :: IO ()
 initDisco = do
-    putStrLn $ "Printing Environment"
-    xs <- getEnvironment
-    forM_ xs $ \(a,b) -> putStrLn $ a <> " = " <> b
-
-    let filename = "/stdlib/num.disco"
-    putStrLn $ "Printing " <> filename
-    putStrLn =<< readFile filename
+    -- NOTE: We set path environment variables here,
+    -- because processing the .wasm module with `wizer` may bake
+    -- them into the code.
+    setEnv "disco_datadir" "stdlib"
 
     s <- runM $ resolveModule' FromStdlib "num"
     print s

www/runtime.js

@@ -30,10 +30,11 @@ export async function runWASM() {
   await addLibFile("prop", fs);
   await addLibFile("string", fs);
 
+  // NOTE: env: may not work on a .wasm module that was
+  // processed with the `wizer` tool.
+  // For this reason,
+  // we set some environment variables inside the .wasm module.
   const wasi = new WASI({
-      env: {
-        disco_datadir: "stdlib"
-      },
       fs: fs,
       stdout: (out) => console.log("[wasm stdout]", out),
   });