Expose GHC.Wasm.Prim from ghc-experimental

Previously this was only exposed from `ghc-internal` which violates our
agreement that users shall not rely on things exposed from that package.

Fixes #24479.

docs/users_guide/wasm.rst

@@ -165,7 +165,7 @@ types in JSFFI. Some caveats to keep in mind:
 
 In addition to the above types, JSFFI supports the ``JSVal`` type and
 its ``newtype``\ s as argument/result types. ``JSVal`` is defined in
-``GHC.Wasm.Prim`` in ``ghc-internal``, which represents an opaque
+``GHC.Wasm.Prim`` in ``ghc-experimental``, which represents an opaque
 reference to a JavaScript value.
 
 ``JSVal``\ s are first-class Haskell values on the Haskell heap. You can

libraries/ghc-experimental/ghc-experimental.cabal

@@ -23,6 +23,8 @@ common warnings
 library
     import:           warnings
     exposed-modules:  GHC.Profiling.Eras
+    if arch(wasm32)
+        exposed-modules:  GHC.Wasm.Prim
     other-extensions:
     build-depends:    base ^>=4.19,
                       ghc-internal >= 0.1 && < 0.2

libraries/ghc-experimental/src/GHC/Wasm/Prim.hs

+{-# LANGUAGE NoImplicitPrelude #-}
+
+module GHC.Wasm.Prim (
+  -- User-facing JSVal type and freeJSVal
+  JSVal (..),
+  freeJSVal,
+
+  -- The JSString type and conversion from/to Haskell String
+  JSString (..),
+  fromJSString,
+  toJSString,
+
+  -- Exception types related to JSFFI
+  JSException (..),
+  WouldBlockException (..),
+  PromisePendingException (..),
+
+  -- Is JSFFI used in the current wasm module?
+  isJSFFIUsed
+) where
+
+import GHC.Internal.Wasm.Prim
+

libraries/ghc-internal/src/GHC/Internal/Wasm/Prim/Conc.hs

@@ -22,7 +22,7 @@ at all, so we can't pretend the old posix style polling works at all.
 
 Since we can do JSFFI async imports now, it's super easy to implement
 threadDelay using setTimeout() in JavaScript, and an implementation
-has indeed been added in GHC.Wasm.Prim.Conc.Internal. But how do we
+has indeed been added in GHC.Internal.Wasm.Prim.Conc.Internal. But how do we
 make the user-facing GHC.Internal.Conc.IO.threadDelay switch to it in browser
 environments and fall back to the stg_delay# implementation otherwise?