build

@@ -1,12 +1,10 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-# generate this file from Nix config for now to avoid duplication?
-
 cargo build --manifest-path ./rust/Cargo.toml
 
 BUNDLED_LIB_DIR=$(cabal list-bin . | sed -e 's=x/garnet/build/garnet/garnet=build=g')
 mkdir -p $BUNDLED_LIB_DIR
-ln -sf $(pwd)/rust/target/debug/libgarnet_rs.a $BUNDLED_LIB_DIR/libCgarnet_rs.a
+ln -sf $(pwd)/rust/target/debug/libgarnet_rs.a $BUNDLED_LIB_DIR
 
 cabal build

cabal.project

@@ -1,5 +1,20 @@
 packages: .
 
+-- not on Hackage yet: https://well-typed.com/blog/2026/02/hs-bindgen-alpha
+-- we've modified the stanzas from that post in order to use a more recent version
+-- because we want record-dot support: https://github.com/well-typed/hs-bindgen/issues/1829#issuecomment-4081875451
+source-repository-package
+  type: git
+  location: https://github.com/well-typed/hs-bindgen
+  tag: 6ca94188abd756a1fb4dd8a4037de3fa7dca0765
+  subdir: c-expr-dsl c-expr-runtime hs-bindgen hs-bindgen-runtime
+  --sha256: M+8tEZA8gsEc6gXnNdSbRpMBQ5LkH7sphcV1aR0fclA=
+source-repository-package
+  type: git
+  location: https://github.com/well-typed/libclang
+  tag: d6e482df49b88375cf3075928a78ee86c2a068d4
+  --sha256: 175kjba915bh50wf03gi88njz03jp0n3wp7yq73hznkaly6bpwal
+
 allow-newer:
   *:base,
   *:containers,

exe/Main.hs

@@ -1,20 +1,13 @@
 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)

flake.lock

@@ -85,11 +85,11 @@
     },
     "crane": {
       "locked": {
-        "lastModified": 1774313767,
+        "lastModified": 1771438068,
-        "narHash": "sha256-hy0XTQND6avzGEUFrJtYBBpFa/POiiaGBr2vpU6Y9tY=",
+        "narHash": "sha256-nGBbXvEZVe/egCPVPFcu89RFtd8Rf6J+4RFoVCFec0A=",
         "owner": "ipetkov",
         "repo": "crane",
-        "rev": "3d9df76e29656c679c744968b17fbaf28f0e923d",
+        "rev": "b5090e53e9d68c523a4bb9ad42b4737ee6747597",
         "type": "github"
       },
       "original": {
@@ -99,21 +99,6 @@
       }
     },
     "flake-compat": {
-      "locked": {
-        "lastModified": 1767039857,
-        "narHash": "sha256-vNpUSpF5Nuw8xvDLj2KCwwksIbjua2LZCqhV1LNRDns=",
-        "owner": "NixOS",
-        "repo": "flake-compat",
-        "rev": "5edf11c44bc78a0d334f6334cdaf7d60d732daab",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "repo": "flake-compat",
-        "type": "github"
-      }
-    },
-    "flake-compat_2": {
       "flake": false,
       "locked": {
         "lastModified": 1672831974,
@@ -151,11 +136,11 @@
     "hackage": {
       "flake": false,
       "locked": {
-        "lastModified": 1770685064,
+        "lastModified": 1771461386,
-        "narHash": "sha256-e2G/GFzIdTXosxq+3Z0OXbSUmXy9tDbZZ6wsmfy7Hf8=",
+        "narHash": "sha256-93hCxhNOq9/HAggfTTurLhllI0IiEWZ35jk6i/X/qEo=",
         "owner": "input-output-hk",
         "repo": "hackage.nix",
-        "rev": "84628a8e4b5d580766d49d62a5e2e065cbb8604e",
+        "rev": "b4f4537825a4db29c10541a50d7eb6c848bf0dca",
         "type": "github"
       },
       "original": {
@@ -167,11 +152,11 @@
     "hackage-for-stackage": {
       "flake": false,
       "locked": {
-        "lastModified": 1770683900,
+        "lastModified": 1771461376,
-        "narHash": "sha256-03cshwLY80e5jBUgNBmoFoiH1e3VvhAX+1ME4NVt5g4=",
+        "narHash": "sha256-aEuZkBpTaU0XBFiaIomicJDoWQaw84rYfKXI/r17V/w=",
         "owner": "input-output-hk",
         "repo": "hackage.nix",
-        "rev": "c7d9e737cd1e07136982e0df0f9aa12391e2c883",
+        "rev": "ca611068e77f15b96ecf71fae827e491c0b2dc3b",
         "type": "github"
       },
       "original": {
@@ -204,7 +189,7 @@
         "cabal-34": "cabal-34",
         "cabal-36": "cabal-36",
         "cardano-shell": "cardano-shell",
-        "flake-compat": "flake-compat_2",
+        "flake-compat": "flake-compat",
         "hackage": "hackage",
         "hackage-for-stackage": "hackage-for-stackage",
         "hackage-internal": "hackage-internal",
@@ -225,7 +210,6 @@
         "hpc-coveralls": "hpc-coveralls",
         "iserv-proxy": "iserv-proxy",
         "nixpkgs": [
-          "nix-haskell",
           "haskell-nix",
           "nixpkgs-unstable"
         ],
@@ -240,17 +224,16 @@
         "stackage": "stackage"
       },
       "locked": {
-        "lastModified": 1773942398,
+        "lastModified": 1771462666,
-        "narHash": "sha256-VFUyPaWqXN357StToBRFbOCZAP4n8iCfEh2ZV1dNH88=",
+        "narHash": "sha256-z+pJFzbYa1ulNDUZdb0qLVVAdE0dqpnE51jqh2chA7c=",
-        "owner": "ymeister",
+        "owner": "input-output-hk",
         "repo": "haskell.nix",
-        "rev": "9fa7c11202e16c8cd2743deed4d811da1cfb2e51",
+        "rev": "857ba7b65d9c1a8765ad1599834a8fe71cb09981",
         "type": "github"
       },
       "original": {
-        "owner": "ymeister",
+        "owner": "input-output-hk",
         "repo": "haskell.nix",
-        "rev": "9fa7c11202e16c8cd2743deed4d811da1cfb2e51",
         "type": "github"
       }
     },
@@ -287,6 +270,23 @@
         "type": "github"
       }
     },
+    "hls-2-13": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1768552477,
+        "narHash": "sha256-Y4XVuyJZnZ++u+wSHlz7xnN9+nk29csahnXDC0QMiGM=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "d744a66a853c287e671e06e62f2a58dd8e7a86d9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "2.13.0.0",
+        "repo": "haskell-language-server",
+        "type": "github"
+      }
+    },
     "hls-2.0": {
       "flake": false,
       "locked": {
@@ -491,23 +491,6 @@
         "type": "github"
       }
     },
-    "hls-src": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1768552477,
-        "narHash": "sha256-Y4XVuyJZnZ++u+wSHlz7xnN9+nk29csahnXDC0QMiGM=",
-        "owner": "haskell",
-        "repo": "haskell-language-server",
-        "rev": "d744a66a853c287e671e06e62f2a58dd8e7a86d9",
-        "type": "github"
-      },
-      "original": {
-        "owner": "haskell",
-        "ref": "2.13.0.0",
-        "repo": "haskell-language-server",
-        "type": "github"
-      }
-    },
     "hpc-coveralls": {
       "flake": false,
       "locked": {
@@ -524,22 +507,6 @@
         "type": "github"
       }
     },
-    "hs-bindgen-src": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1776078838,
-        "narHash": "sha256-f8SE6IuACy8bzIX+EOYTpekaAI/TOQ3zTwJKJmHl3LY=",
-        "owner": "well-typed",
-        "repo": "hs-bindgen",
-        "rev": "ca714aca1ed941271ac248488c9a469554c5b470",
-        "type": "github"
-      },
-      "original": {
-        "owner": "well-typed",
-        "repo": "hs-bindgen",
-        "type": "github"
-      }
-    },
     "iserv-proxy": {
       "flake": false,
       "locked": {
@@ -557,59 +524,6 @@
         "type": "github"
       }
     },
-    "libclang-src": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1775645278,
-        "narHash": "sha256-JWARcbqH432vWcCvQ2bagTXBka8sCRNAnK1qOmnLWKw=",
-        "owner": "well-typed",
-        "repo": "libclang",
-        "rev": "bf574efcb492d2738d8a82b6ce556f840ff92778",
-        "type": "github"
-      },
-      "original": {
-        "owner": "well-typed",
-        "repo": "libclang",
-        "type": "github"
-      }
-    },
-    "nix-haskell": {
-      "inputs": {
-        "flake-compat": "flake-compat",
-        "haskell-nix": "haskell-nix",
-        "nixpkgs": "nixpkgs",
-        "reflex-platform": "reflex-platform"
-      },
-      "locked": {
-        "lastModified": 1774408168,
-        "narHash": "sha256-do26Ik50yH8NYSxuhwzBwNKsxIN88GoovwioWPvCpJU=",
-        "owner": "reflex-frp",
-        "repo": "nix-haskell",
-        "rev": "d6a3bb8f96ff35fd0ae2a0d64f40b584c92aa493",
-        "type": "github"
-      },
-      "original": {
-        "owner": "reflex-frp",
-        "repo": "nix-haskell",
-        "type": "github"
-      }
-    },
-    "nixpkgs": {
-      "locked": {
-        "lastModified": 1769089682,
-        "narHash": "sha256-9yA/LIuAVQq0lXelrZPjLuLVuZdm03p8tfmHhnDIkms=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "078d69f03934859a181e81ba987c2bb033eebfc5",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "078d69f03934859a181e81ba987c2bb033eebfc5",
-        "type": "github"
-      }
-    },
     "nixpkgs-2305": {
       "locked": {
         "lastModified": 1705033721,
@@ -739,34 +653,15 @@
         "type": "github"
       }
     },
-    "reflex-platform": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1760924715,
-        "narHash": "sha256-pUraGts8qa3R9jQqaVXevkC+nM07B8oF+LGF4xsyiJU=",
-        "owner": "reflex-frp",
-        "repo": "reflex-platform",
-        "rev": "4482ecb04c5939ac77c26d769d149dee12051a13",
-        "type": "github"
-      },
-      "original": {
-        "owner": "reflex-frp",
-        "repo": "reflex-platform",
-        "rev": "4482ecb04c5939ac77c26d769d149dee12051a13",
-        "type": "github"
-      }
-    },
     "root": {
       "inputs": {
         "crane": "crane",
         "flake-utils": "flake-utils",
-        "hls-src": "hls-src",
+        "haskell-nix": "haskell-nix",
-        "hs-bindgen-src": "hs-bindgen-src",
+        "hls-2-13": "hls-2-13",
-        "libclang-src": "libclang-src",
-        "nix-haskell": "nix-haskell",
         "nixpkgs": [
-          "nix-haskell",
+          "haskell-nix",
-          "nixpkgs"
+          "nixpkgs-2511"
         ],
         "rust-overlay": "rust-overlay"
       }
@@ -778,11 +673,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1774408260,
+        "lastModified": 1771470520,
-        "narHash": "sha256-Jn9d9r85dmf3gTMnSRt6t+DP2nQ5uJns/MMXg2FpzfM=",
+        "narHash": "sha256-PvytHcaYN5cPUll7FB70mXv1rRsIBRmu47fFfq3haxA=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "d6471ee5a8f470251e6e5b83a20a182eb6c46c9b",
+        "rev": "a1d4cc1f264c45d3745af0d2ca5e59d460e58777",
         "type": "github"
       },
       "original": {
@@ -794,11 +689,11 @@
     "stackage": {
       "flake": false,
       "locked": {
-        "lastModified": 1770596307,
+        "lastModified": 1771460325,
-        "narHash": "sha256-88b6YzeBaQr9ihSWAOxVGewCDfROKt2rOIHymadu3DI=",
+        "narHash": "sha256-RRsGO7QVyuBtUTVqDiB7CYvFruj0Z/yxZK1JarkTqI4=",
         "owner": "input-output-hk",
         "repo": "stackage.nix",
-        "rev": "ff21e9b6a976faed56963ae5fa5d5396dc48ea63",
+        "rev": "29c0dcc517e04be238023064412312ad4443ddb2",
         "type": "github"
       },
       "original": {

flake.nix

@@ -1,10 +1,8 @@
 {
   inputs = {
-    nix-haskell.url = "github:reflex-frp/nix-haskell";
+    haskell-nix.url = "github:input-output-hk/haskell.nix";
-    nixpkgs.follows = "nix-haskell/nixpkgs";
+    hls-2-13 = { url = "github:haskell/haskell-language-server/2.13.0.0"; flake = false; };
-    hls-src = { url = "github:haskell/haskell-language-server/2.13.0.0"; flake = false; };
+    nixpkgs.follows = "haskell-nix/nixpkgs-2511";
-    hs-bindgen-src = { url = "github:well-typed/hs-bindgen"; flake = false; };
-    libclang-src = { url = "github:well-typed/libclang"; flake = false; };
     flake-utils.url = "github:numtide/flake-utils";
     crane.url = "github:ipetkov/crane";
     rust-overlay = {
@@ -13,96 +11,51 @@
     };
   };
   outputs =
-    inputs:
+    inputs@{ nixpkgs, ... }:
     inputs.flake-utils.lib.eachSystem [ "x86_64-linux" ] (system:
     let
-      pkgs = haskell.nixpkgs.extend (import inputs.rust-overlay);
+      overlays = [
-      crane = (inputs.crane.mkLib pkgs).overrideToolchain (p: p.rust-bin.selectLatestNightlyWith (
+        inputs.haskell-nix.overlay
+        (final: _prev: {
+          hixProject =
+            final.haskell-nix.hix.project {
+              src = ./.;
+              evalSystem = "x86_64-linux";
+              name = "garnet";
+              compiler-nix-name = "ghc9141";
+              shell.tools.cabal = "latest";
+              shell.withHoogle = false;
+              shell.tools.haskell-language-server = {
+                src = inputs.hls-2-13;
+                sha256map = {
+                  "https://github.com/snowleopard/alga"."d4e43fb42db05413459fb2df493361d5a666588a" = "0s1mlnl64wj7pkg3iipv5bb4syy3bhxwqzqv93zqlvkyfn64015i";
+                };
+              };
+            };
+        })
+        (import inputs.rust-overlay)
+      ];
+      pkgs = import nixpkgs { inherit system overlays; inherit (inputs.haskell-nix) config; };
+      haskell = pkgs.hixProject.flake { };
+      rust = (inputs.crane.mkLib pkgs).overrideToolchain (p: p.rust-bin.selectLatestNightlyWith (
         toolchain: toolchain.default.override {
-          extensions = [ "rust-src" "rust-analyzer" ];
+          extensions = [ "rust-src" ];
           targets = [ "x86_64-unknown-linux-gnu" ];
         }
       ));
-      addLibcIncludeDir =
-        ''
-          export C_INCLUDE_PATH="${pkgs.stdenv.cc.libc.dev}/include''${C_INCLUDE_PATH:+:$C_INCLUDE_PATH}"
-        '';
-      haskell = (import inputs.nix-haskell { inherit system inputs; } {
-        name = "garnet";
-        src = ./.;
-        compiler-nix-name = "ghc914";
-        source-repository-packages = {
-          # not on Hackage yet: https://well-typed.com/blog/2026/02/hs-bindgen-alpha
-          # we're using more recent versions than in that post, because we want record-dot support:
-          # https://github.com/well-typed/hs-bindgen/issues/1829#issuecomment-4081875451
-          c-expr-dsl = inputs.hs-bindgen-src + "/c-expr-dsl";
-          c-expr-runtime = inputs.hs-bindgen-src + "/c-expr-runtime";
-          hs-bindgen = inputs.hs-bindgen-src + "/hs-bindgen";
-          hs-bindgen-runtime = inputs.hs-bindgen-src + "/hs-bindgen-runtime";
-          libclang-bindings = inputs.libclang-src;
-        };
-        overrides = [
-          ({ pkgs, ... }: {
-            packages.libclang-bindings.components.library = {
-              build-tools = [ pkgs.llvmPackages.llvm ];
-              libs = [ pkgs.llvmPackages.libclang ];
-            };
-            packages.garnet.components.library = {
-              preBuild = addLibcIncludeDir;
-              # try removing?
-              preConfigure = ''
-                mkdir -p rust/target/debug
-                ln -s ${garnet-rs}/include/garnet_rs.h rust/target/debug/garnet_rs.h
-              '';
-              preInstall = ''
-                cp ${garnet-rs}/lib/libCgarnet_rs.a dist/build/libCgarnet_rs.a
-              '';
-              configureFlags = [ "--extra-lib-dirs=${garnet-rs}/lib" ];
-            };
-          })
-        ];
-        shell = {
-          tools = {
-            cabal = "latest";
-            haskell-language-server = {
-              src = inputs.hls-src;
-              sha256map = {
-                "https://github.com/snowleopard/alga" = {
-                  "d4e43fb42db05413459fb2df493361d5a666588a" = "0s1mlnl64wj7pkg3iipv5bb4syy3bhxwqzqv93zqlvkyfn64015i";
-                };
-              };
-            };
-          };
-          withHoogle = false;
-          withHaddock = true;
-          shellHook = addLibcIncludeDir;
-        };
-      });
-      garnet-rs = crane.buildPackage {
-        src = crane.cleanCargoSource ./rust;
-        doCheck = false;
-        installPhaseCommand = ''
-          mkdir -p $out/lib $out/include
-          cp target/release/libgarnet_rs.a $out/lib/libCgarnet_rs.a
-          cp target/release/garnet_rs.h $out/include/
-        '';
-      };
     in
-    rec {
+    {
-      defaultPackage = packages.garnet-exe;
-      packages = let garnet = haskell.project.haskell-nix.hsPkgs.garnet; in {
-        inherit garnet-rs;
-        garnet-exe = garnet.components.exes.garnet;
-        garnet-lib = garnet.components.library;
-      };
       devShells.default = pkgs.mkShell {
         inputsFrom = [
-          haskell.project.haskell-nix.shell
+          haskell.devShells.default
-          (crane.devShell { })
+          (rust.devShell { })
         ];
         packages = with pkgs; [
           bacon
           ghcid
+          llvmPackages.libclang
+          llvmPackages.llvm
+          rust-analyzer
         ];
       };
     });

garnet.cabal

@@ -6,21 +6,6 @@ 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
-
--- actually maybe this is pointless given we always need debug path anyway in `extra-source-files`
--- plus we have it in `Raw.hs`
-flag dev
-  default:
-    False
-  manual:
-    True
 
 common common
     default-language: GHC2024
@@ -37,20 +22,17 @@ common common
         NoMonomorphismRestriction
         OverloadedRecordDot
         OverloadedStrings
-        PatternSynonyms
         RecordWildCards
         ViewPatterns
     ghc-options:
         -Wall
         -fdefer-type-errors
     build-depends:
-        base,
         bytestring,
         extra,
         mtl,
         process,
         text,
-        vector,
 
 library
     import: common
@@ -58,16 +40,13 @@ library
         GarnetRs.Raw
         GarnetRs.Wrapped
     hs-source-dirs: lib
-    -- if flag (dev)
-        -- include-dirs: rust/target/debug
     include-dirs: rust/target/debug
-    -- HLS gives up entirely when the header is malformed if we do this
+    extra-bundled-libraries: garnet_rs
-    -- 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,
+        primitive,
         template-haskell,
 
 executable garnet
@@ -79,4 +58,5 @@ executable garnet
         -rtsopts
         -with-rtsopts=-N
     build-depends:
+        base,
         garnet,

lib/GarnetRs/Raw.hs

@@ -1,5 +1,6 @@
 {-# LANGUAGE CApiFFI #-}
 {-# LANGUAGE DerivingVia #-}
+{-# LANGUAGE FieldSelectors #-}
 {-# LANGUAGE MagicHash #-}
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE TemplateHaskell #-}
@@ -29,10 +30,19 @@ import HsBindgen.TH
 import Language.Haskell.TH
 import System.Process
 
+do
+    systemDirs <- -- TODO bit of a hack
+        map (Dir . T.unpack . T.strip)
+            . concatMap (takeWhile (maybe False ((== ' ') . fst) . T.uncons) . dropWhile T.null . T.lines)
+            . drop 1
+            . T.splitOn "search starts here:"
+            . T.pack
+            . thd3
+            <$> runIO (readProcessWithExitCode "cpp" ["-v"] "")
     withHsBindgen
         def
-        { clang = def{extraIncludeDirs = [Pkg "rust/target/debug"]}
+            { clang = def{extraIncludeDirs = Pkg "rust/target/debug" : systemDirs}
-        , fieldNamingStrategy = OmitFieldPrefixes
+            , fieldNamingStrategy = EnableRecordDot
             }
         def
         $ hashInclude "garnet_rs.h"

lib/GarnetRs/Wrapped.hs

@@ -2,29 +2,19 @@
 -- 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
@@ -44,8 +34,8 @@ data Shape
     | Rectangle CDouble CDouble
 convertShape :: Shape -> Raw.Shape
 convertShape = \case
-    Circle r -> Raw.Shape Raw.Circle $ Raw.set_shape_circle_circle $ Raw.Circle_Body r
+    Circle r -> Raw.Shape Raw.Circle $ Raw.set_shape_body_circle $ Raw.Circle_Body r
-    Rectangle w h -> Raw.Shape Raw.Rectangle $ Raw.set_shape_circle_rectangle $ Raw.Rectangle_Body w h
+    Rectangle w h -> Raw.Shape Raw.Rectangle $ Raw.set_shape_body_rectangle $ Raw.Rectangle_Body w h
 
 data BTree a
     = Leaf a
@@ -53,38 +43,27 @@ data BTree a
 withBTree :: BTree Int64 -> (Raw.BTreeC -> IO a) -> IO a
 withBTree =
     runContT . fix \f -> \case
-        Leaf v -> pure $ Raw.BTreeC Raw.Leaf $ Raw.set_bTreeC_leaf_leaf $ Raw.Leaf_Body v
+        Leaf v -> pure $ Raw.BTreeC Raw.Leaf $ Raw.set_bTreeC_body_leaf $ Raw.Leaf_Body v
         Fork l r -> do
             lRaw <- f l
             rRaw <- f r
             lPtr <- ContT alloca
             rPtr <- ContT alloca
             lift $ poke lPtr lRaw >> poke rPtr rRaw
-            pure . Raw.BTreeC Raw.Fork . Raw.set_bTreeC_leaf_fork $
+            pure . Raw.BTreeC Raw.Fork . Raw.set_bTreeC_body_fork $
                 Raw.Fork_Body (unsafeFromPtr lPtr) (unsafeFromPtr rPtr)
 
 hello :: ByteString -> IO ()
-hello bs = useAsCString bs \ptr -> Raw.hello $ unsafeFromPtr ptr
+hello s = useAsCString s $ Raw.hello . unsafeFromPtr
 
 helloStruct :: T -> IO ()
-helloStruct t = with (convertT t) \ptr -> Raw.hello_struct $ unsafeFromPtr ptr
+helloStruct = Raw.hello_struct . convertT
-
-helloEnum :: Raw.E -> IO ()
-helloEnum e = with e \ptr -> Raw.hello_enum $ unsafeFromPtr ptr
 
 helloShape :: Shape -> IO ()
-helloShape s = with (convertShape s) \ptr -> Raw.hello_shape $ unsafeFromPtr ptr
+helloShape = Raw.hello_shape . convertShape
 
 add :: Int64 -> Int64 -> Int64
 add = Raw.add
 
 sumTree :: BTree Int64 -> Int64
-sumTree t = unsafePerformIO $ withBTree t \tc -> with tc \ptr -> Raw.sum_tree $ unsafeFromPtr ptr
+sumTree = unsafePerformIO . flip withBTree Raw.sum_tree
-
-sumSlice :: V.Vector Int64 -> Int64
-sumSlice v = unsafePerformIO $ V.unsafeWith v \ptr -> Raw.sum_slice (unsafeFromPtr ptr) (fromIntegral $ V.length v)
-
-printOptional :: Maybe Int8 -> IO ()
-printOptional = \case
-    Nothing -> Raw.print_optional $ unsafeFromPtr nullPtr
-    Just t -> with t \ptr -> Raw.print_optional $ unsafeFromPtr ptr

rust/build.rs

@@ -1,36 +1,43 @@
 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
-    // and that's really not helped by Rust Analyzer mostly only showing diagnostics on save
-    // 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(
+
+    // TODO vibe-coded workaround for hs-bindgen issue:
+    // https://github.com/well-typed/hs-bindgen/issues/1649#issuecomment-3994425922
+    let mut buf = Vec::new();
+    bindings.write(&mut buf);
+    let header = String::from_utf8(buf).unwrap();
+    let mut patched = String::new();
+    let mut saw_union = false;
+    for line in header.lines() {
+        if line == "  };" && saw_union {
+            patched.push_str("  } body;\n");
+            saw_union = false;
+            continue;
+        }
+        if line == "  union {" {
+            saw_union = true;
+        }
+        patched.push_str(line);
+        patched.push('\n');
+    }
+    fs::write(
         PathBuf::from(&crate_dir)
             .join("target")
             .join(&profile)
             .join("garnet_rs.h"),
-        );
+        patched,
+    )
+    .unwrap();
 }

rust/lib.rs

@@ -3,7 +3,6 @@
 use std::{
     ffi::{CStr, c_char},
     ops::Add,
-    slice,
 };
 
 fn say_hello(name: &str) {
@@ -11,7 +10,7 @@ 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())
 }
 
@@ -23,23 +22,10 @@ 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 {
@@ -48,7 +34,7 @@ enum Shape {
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn hello_shape(s: &Shape) {
+extern "C" fn hello_shape(s: Shape) -> () {
     say_hello(&format!("{:?}", s))
 }
 
@@ -92,19 +78,6 @@ 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::<_, &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>) -> () {
-    match x {
-        Some(x) => println!("{}", x / 2),
-        None => {}
-    }
 }