basic enum example

exe/Main.hs

@@ -9,6 +9,8 @@ main = do
     hello "Haskell"
     helloStruct T{a = True, b = 42}
     helloStruct T{a = False, b = maxBound}
+    helloEnum E1
+    helloEnum E3
     helloShape $ Circle 3.14
     helloShape $ Rectangle 10.0 5.0
     putStrLn $ "3 + 4 = " <> show (add 3 4)

lib/GarnetRs/Wrapped.hs

@@ -1,11 +1,20 @@
+{-# LANGUAGE PatternSynonyms #-}
+
 -- TODO automate this sort of high level wrapper boilerplate
 -- or look at upstream plans: https://github.com/well-typed/hs-bindgen/issues?q=state%3Aopen%20label%3A%22highlevel%22
 module GarnetRs.Wrapped (
     T (..),
+    Raw.E (..),
+    -- TODO hmm, we don't really want to have to list all of these...
+    -- is there an option to make them not be patterns at all?
+    pattern Raw.E1,
+    pattern Raw.E2,
+    pattern Raw.E3,
     Shape (..),
     BTree (..),
     hello,
     helloStruct,
+    helloEnum,
     helloShape,
     add,
     sumTree,
@@ -62,6 +71,9 @@ hello s = useAsCString s $ Raw.hello . unsafeFromPtr
 helloStruct :: T -> IO ()
 helloStruct = flip with (Raw.hello_struct . unsafeFromPtr) . convertT
 
+helloEnum :: Raw.E -> IO ()
+helloEnum = flip with (Raw.hello_enum . unsafeFromPtr)
+
 helloShape :: Shape -> IO ()
 helloShape = flip with (Raw.hello_shape . unsafeFromPtr) . convertShape
 

rust/lib.rs

@@ -27,6 +27,19 @@ extern "C" fn hello_struct(t: &T) -> () {
     say_hello(&format!("{:?}", t))
 }
 
+#[repr(C)]
+#[derive(Debug)]
+enum E {
+    E1,
+    E2,
+    E3,
+}
+
+#[unsafe(no_mangle)]
+extern "C" fn hello_enum(e: &E) {
+    say_hello(&format!("{:?}", e))
+}
+
 #[repr(C)]
 #[derive(Debug)]
 enum Shape {