Base/JS: GHC.JS.Foreign.Callback module (issue 23126)

* Add the Callback module for "exporting" Haskell functions
to be available to plain JavaScript code

* Fix some primitives defined in GHC.JS.Prim

* Add a JavaScript section to the user guide with instructions
on how to use the JavaScript FFI, building up to using Callbacks
to interact with the browser

* Add tests for the JavaScript FFI and Callbacks

1 files changed, 18 insertions, 0 deletions

diff --git a/testsuite/tests/javascript/js-ffi-array.hs b/testsuite/tests/javascript/js-ffi-array.hs
new file mode 100644
index 0000000000..00e1e80383
--- /dev/null
+++ b/testsuite/tests/javascript/js-ffi-array.hs
@@ -0,0 +1,18 @@
+import GHC.JS.Prim
+
+foreign import javascript "((xs) => { console.log(xs) })"
+  log_js :: JSVal -> IO ()
+
+foreign import javascript "((xs,i) => { return xs[i]; })"
+  js_index :: JSVal -> JSVal -> JSVal
+
+foreign import javascript "(() => { return ['t','e','s','t']; })"
+  an_array :: JSVal
+
+main :: IO ()
+main = do
+  log_js =<< toJSArray []
+  log_js =<< toJSArray [jsNull, toJSInt 0, toJSString "", toJSInt 1, toJSString "test", toJSInt 2]
+  xs <- toJSArray $ map toJSInt [1..10]
+  log_js $ js_index xs (toJSInt 3)
+  mapM_ log_js =<< fromJSArray an_array