basic enum example

Seeing as we now no longer need to modify generated header files.

exe/Main.hs

@@ -1,13 +1,20 @@
 module Main (main) where
 
+import Data.Vector.Storable qualified as V
 import GarnetRs.Wrapped
+import System.IO
 
 main :: IO ()
 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)
     putStrLn $ "Tree sum: " <> show (sumTree (Fork (Fork (Leaf 1) (Fork (Leaf 2) (Leaf 3))) (Leaf 4)))
+    putStrLn $ "Slice sum: " <> show (sumSlice $ V.fromList [0 .. 5])
+    putStrLn "Nothing." >> printOptional Nothing
+    putStr "Something: " >> hFlush stdout >> printOptional (Just 67)

garnet.cabal

@@ -6,6 +6,13 @@ author: Patrick Aldis
 maintainer:
     george.thomas@obsidian.systems
     patrick.aldis@obsidian.systems
+-- aha, nice, this does fix recompilation checking
+extra-source-files:
+    rust/target/debug/garnet_rs.h
+-- that could be problematic given file is gitignored? unfortunately this doesn't work
+-- tbf, I haven't even looked up the docs, just saw the autocompletion
+-- extra-tmp-files:
+--     rust/target/debug/garnet_rs.h
 
 common common
     default-language: GHC2024
@@ -28,11 +35,13 @@ common common
         -Wall
         -fdefer-type-errors
     build-depends:
+        base,
         bytestring,
         extra,
         mtl,
         process,
         text,
+        vector,
 
 library
     import: common
@@ -41,9 +50,11 @@ library
         GarnetRs.Wrapped
     hs-source-dirs: lib
     include-dirs: rust/target/debug
+    -- HLS gives up entirely when the header is malformed if we do this
+    -- and anyway, I don't think it gives us dependency tracking like `extra-source-files` does
+    -- includes: garnet_rs.h
     extra-bundled-libraries: Cgarnet_rs
     build-depends:
-        base,
         hs-bindgen,
         hs-bindgen-runtime,
         template-haskell,
@@ -57,5 +68,4 @@ executable garnet
         -rtsopts
         -with-rtsopts=-N
     build-depends:
-        base,
         garnet,

lib/GarnetRs/Raw.hs

@@ -29,7 +29,15 @@ import HsBindgen.TH
 import Language.Haskell.TH
 import System.Process
 
+import Control.Monad.IO.Class (MonadIO (liftIO))
+import Language.Haskell.TH.Syntax (addDependentFile)
+import System.Directory.Extra (getCurrentDirectory)
+
 do
+    -- not sure this does anything - hs-bindgen should already be doing the tracking, and the issues are from elsewhere
+    -- dir <- liftIO getCurrentDirectory
+    -- liftIO $ print dir
+    -- addDependentFile $ dir <> "/rust/target/debug/garnet_rs.h"
     systemDirs <- -- TODO bit of a hack
         map (Dir . T.unpack . T.strip)
             . concatMap (takeWhile (maybe False ((== ' ') . fst) . T.uncons) . dropWhile T.null . T.lines)

lib/GarnetRs/Wrapped.hs

@@ -1,20 +1,32 @@
+{-# 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,
+    sumSlice,
+    printOptional,
 ) where
 
 import Control.Monad.Cont
 import Control.Monad.Trans
 import Data.ByteString
 import Data.Function
+import Data.Vector.Storable qualified as V
 import Data.Word
 import Foreign
 import Foreign.C
@@ -54,16 +66,27 @@ withBTree =
                 Raw.Fork_Body (unsafeFromPtr lPtr) (unsafeFromPtr rPtr)
 
 hello :: ByteString -> IO ()
-hello s = useAsCString s $ Raw.hello . unsafeFromPtr
+hello = flip useAsCString $ Raw.hello . unsafeFromPtr
 
 helloStruct :: T -> IO ()
-helloStruct = Raw.hello_struct . convertT
+helloStruct = flip with (Raw.hello_struct . unsafeFromPtr) . convertT
+
+helloEnum :: Raw.E -> IO ()
+helloEnum = flip with (Raw.hello_enum . unsafeFromPtr)
 
 helloShape :: Shape -> IO ()
-helloShape = Raw.hello_shape . convertShape
+helloShape = flip with (Raw.hello_shape . unsafeFromPtr) . convertShape
 
 add :: Int64 -> Int64 -> Int64
 add = Raw.add
 
 sumTree :: BTree Int64 -> Int64
-sumTree = unsafePerformIO . flip withBTree Raw.sum_tree
+sumTree = unsafePerformIO . flip withBTree (flip with $ Raw.sum_tree . unsafeFromPtr)
+
+sumSlice :: V.Vector Int64 -> Int64
+sumSlice v = unsafePerformIO $ V.unsafeWith v \p -> Raw.sum_slice (unsafeFromPtr p) (fromIntegral $ V.length v)
+
+printOptional :: Maybe Int8 -> IO ()
+printOptional = \case
+    Nothing -> Raw.print_optional (unsafeFromPtr nullPtr)
+    Just t -> with t (Raw.print_optional . unsafeFromPtr)

project.nix

@@ -19,6 +19,8 @@
   };
   overrides = [
     ({ pkgs, ... }: {
+      # TODO get this upstreamed:
+      # https://input-output-hk.github.io/haskell.nix/tutorials/pkg-map.html#mapping-in-haskellnix
       packages.libclang-bindings.components.library = {
         build-tools = [ pkgs.llvmPackages.llvm ];
         libs = [ pkgs.llvmPackages.libclang ];

rust/build.rs

@@ -1,27 +1,35 @@
 use std::env;
-use std::fs;
 use std::path::PathBuf;
 
 fn main() {
+    // this doesn't make _much_ difference really, since this is our only Rust source file
+    // but it seems it's probably better than not having it
+    // what we really want is to tell Rust to only regenerate the header file if the Rust code actually compiles
+    // but we don't have that flexibility
+    // and it's an issue because cbindgen tries to be fault-tolerant in some ways that don't even seem to make sense
+    //
+    // e.g. mis-spell "Option" as "Option" and you get
+    // void print_optional(Optio<const int8_t*> x);
+    // instead of
+    // void print_optional(const int8_t *x);
+    // and that's only an issue because in HLS TH dependent-file watching gives up after an error
+    // i.e. once the containing splice has thrown an exception once, the containing file needs a manual edit to kick it
+    // P.S. strings to stdout?! what a terrible API
+    // don't get me started in the discoverability of actually then using the terminal for debugging:
+    // println!("cargo::warning={:?}", env::var("OUT_DIR"));
+    println!("cargo::rerun-if-changed=lib.rs");
     let crate_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
     let profile = env::var("PROFILE").unwrap();
-
+    cbindgen::Builder::new()
-    let bindings = cbindgen::Builder::new()
         .with_crate(&crate_dir)
         .with_language(cbindgen::Language::C)
         .with_style(cbindgen::Style::Tag)
         .generate()
-        .expect("Unable to generate bindings");
+        .expect("Unable to generate bindings")
-
+        .write_to_file(
-    let mut buf = Vec::new();
-    bindings.write(&mut buf);
-    let header = String::from_utf8(buf).unwrap();
-    fs::write(
             PathBuf::from(&crate_dir)
                 .join("target")
                 .join(&profile)
                 .join("garnet_rs.h"),
-        header,
+        );
-    )
-    .unwrap();
 }

rust/lib.rs

@@ -3,6 +3,7 @@
 use std::{
     ffi::{CStr, c_char},
     ops::Add,
+    slice,
 };
 
 fn say_hello(name: &str) {
@@ -10,7 +11,7 @@ fn say_hello(name: &str) {
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn hello(c: *const c_char) -> () {
+extern "C" fn hello(c: *const c_char) {
     say_hello(unsafe { CStr::from_ptr(c) }.to_str().unwrap())
 }
 
@@ -22,10 +23,23 @@ struct T {
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn hello_struct(t: T) -> () {
+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 {
@@ -34,7 +48,7 @@ enum Shape {
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn hello_shape(s: Shape) -> () {
+extern "C" fn hello_shape(s: &Shape) {
     say_hello(&format!("{:?}", s))
 }
 
@@ -78,6 +92,18 @@ enum BTreeC {
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn sum_tree(t: BTreeC) -> i64 {
+extern "C" fn sum_tree(t: &BTreeC) -> i64 {
-    (unsafe { std::mem::transmute::<_, &BTree<i64>>(&t) }).sum()
+    (unsafe { std::mem::transmute::<&BTreeC, &BTree<i64>>(t) }).sum()
+}
+
+#[unsafe(no_mangle)]
+extern "C" fn sum_slice(v: *const i64, s: usize) -> i64 {
+    unsafe { slice::from_raw_parts(v, s) }.iter().sum()
+}
+
+#[unsafe(no_mangle)]
+extern "C" fn print_optional(x: Option<&i8>) {
+    if let Some(x) = x {
+        println!("{}", x / 2)
+    }
 }