Coln compiler as WebAssembly library

cabal.project

@@ -1,5 +1,20 @@
 packages:
-  packages/*/*.cabal
+  packages/diagnostician
+  packages/diagnostician-terminal
+  packages/diagnostician-html
+  packages/fnotation
+  packages/coln-compiler
+if !os(wasi)
+  packages:
+    packages/coln-manual-dev
+    packages/coln-do
+    packages/coln-repl
+    packages/coln-ls
+    packages/coln-cli
+else
+  packages:
+    packages/coln-wasm
+
 jobs: $ncpus
 semaphore: true
 tests: True
@@ -9,3 +24,10 @@ constraints:
   -- https://github.com/haskell/lsp/issues/641
   lsp >= 2.8.0.0,
   lsp-types >= 2.4,
+
+if impl(ghc >= 9.14)
+  allow-newer:
+    -- https://github.com/dmwit/ordered-containers/pull/36
+    ordered-containers:containers,
+    -- https://github.com/georgefst/prettyprinter-lucid/issues/7
+    prettyprinter-lucid:base,

flake.nix

@@ -3,6 +3,7 @@
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-26.05";
     flake-utils.url = "github:numtide/flake-utils";
     rust-overlay.url = "github:oxalica/rust-overlay";
+    ghc-wasm-meta.url = "gitlab:haskell-wasm/ghc-wasm-meta?host=gitlab.haskell.org";
   };
   outputs =
     inputs@{
@@ -156,6 +157,7 @@
         };
 
         inherit (packages) forester coln-manual-dev;
+        haskell-wasm = inputs.ghc-wasm-meta.packages.${system}.default;
       in
       {
         inherit packages;
@@ -177,9 +179,11 @@
             forester
             fourmolu
             esbuild
+            haskell-wasm
             haskell.compiler.ghc912
             haskell.packages.ghc912.haskell-language-server
             haskellPackages.cabal-gild
+            jq
             just
             nodejs
             pnpm
@@ -190,6 +194,7 @@
             openssl
             pkg-config
             reuse
+            simple-http-server
             tectonic
             typescript
             zlib

packages/coln-cli/coln-cli.cabal

@@ -23,7 +23,7 @@ executable coln
     Coln.CLI.REPL
 
   build-depends:
-    base ^>=4.21.0.0,
+    base ^>=4.21.0.0 || ^>=4.22,
     coln-compiler,
     coln-ls,
     coln-repl,

packages/coln-do/coln-do.cabal

@@ -22,7 +22,7 @@ executable coln-do
   default-language: GHC2024
   ghc-options: -Wall
   build-depends:
-    base ^>=4.21.0.0,
+    base ^>=4.21.0.0 || ^>=4.22,
     bytestring,
     directory,
     djot,

packages/coln-manual-dev/coln-manual-dev.cabal

@@ -15,7 +15,7 @@ executable coln-manual-dev
   main-is: Main.hs
   build-depends:
     async,
-    base ^>=4.21.0.0,
+    base ^>=4.21.0.0 || ^>=4.22,
     bytestring,
     directory,
     extra,

packages/coln-wasm/Lib.hs

@@ -0,0 +1,71 @@
+-- SPDX-FileCopyrightText: 2026 Coln contributors
+--
+-- SPDX-License-Identifier: Apache-2.0 OR MIT
+
+module Lib () where
+
+import Coln.Backend.IR qualified as I
+import Coln.Backend.Lower
+import Coln.Core.Globals
+import Coln.Diagnostics
+import Coln.Frontend.Driver
+import Control.Monad
+import Data.Aeson.Text qualified as Aeson
+import Data.Foldable
+import Data.IORef
+import Data.Map.Ordered qualified as OMap
+import Data.Text (Text)
+import Data.Text qualified as T
+import Data.Text.Lazy qualified as TL
+import Diagnostician
+import Diagnostician.HTML (diagnosticToHtml)
+import Foreign.StablePtr
+import GHC.Wasm.Prim
+import Lucid qualified
+import Prettyprinter
+import Prettyprinter.Render.Text qualified as Text
+
+data CompileResult = CompileResult
+  { ir :: [I.FlatRealm]
+  , diagnostics :: [Diagnostic ColnCode]
+  }
+foreign export javascript "freeCompileResult" freeStablePtr :: StablePtr CompileResult -> IO ()
+
+compile :: JSString -> IO (StablePtr CompileResult)
+compile src = do
+  ref <- newIORef []
+  globals <- topFromText (pureReporter ref) (newFile "<wasm>" $ textFromJSString src)
+  let ir = map (uncurry lowerRealm) $ OMap.assocs globals.realms
+  diagnostics <- reverse <$> readIORef ref
+  newStablePtr CompileResult{ir, diagnostics}
+foreign export javascript "compile" compile :: JSString -> IO (StablePtr CompileResult)
+
+getDiagnostics :: Bool -> StablePtr CompileResult -> IO JSVal
+getDiagnostics asHtml = jsStringArray . map (textToJSString . TL.toStrict . render) . (.diagnostics) <=< deRefStablePtr
+ where
+  render =
+    if asHtml
+      then Lucid.renderText . diagnosticToHtml
+      else Text.renderLazy . layoutPretty defaultLayoutOptions . dpretty
+foreign export javascript "getDiagnostics" getDiagnostics :: Bool -> StablePtr CompileResult -> IO JSVal
+
+prettyIr :: StablePtr CompileResult -> IO JSVal
+prettyIr = jsStringArray . map (textToJSString . T.show) . (.ir) <=< deRefStablePtr
+foreign export javascript "prettyIr" prettyIr :: StablePtr CompileResult -> IO JSVal
+
+irToJson :: StablePtr CompileResult -> IO JSString
+irToJson = fmap (textToJSString . TL.toStrict . Aeson.encodeToLazyText . (.ir)) . deRefStablePtr
+foreign export javascript "irToJson" irToJson :: StablePtr CompileResult -> IO JSString
+
+textToJSString :: Text -> JSString
+textToJSString = toJSString . T.unpack
+textFromJSString :: JSString -> Text
+textFromJSString = T.pack . fromJSString
+
+foreign import javascript unsafe "[]" js_new_array :: IO JSVal
+foreign import javascript unsafe "$1.push($2)" js_push_string :: JSVal -> JSString -> IO ()
+jsStringArray :: [JSString] -> IO JSVal
+jsStringArray ss = do
+  arr <- js_new_array
+  for_ ss $ js_push_string arr
+  pure arr

packages/coln-wasm/coln-wasm.cabal

@@ -0,0 +1,31 @@
+cabal-version: 3.4
+name: coln-wasm
+version: 0.1
+
+executable coln-wasm
+  main-is: Lib.hs
+  hs-source-dirs: .
+  default-language: GHC2024
+  default-extensions:
+    NoFieldSelectors
+    OverloadedRecordDot
+    OverloadedStrings
+
+  build-depends:
+    aeson,
+    base,
+    coln-compiler,
+    containers,
+    diagnostician,
+    diagnostician-html,
+    fnotation,
+    ghc-experimental,
+    lucid,
+    ordered-containers,
+    prettyprinter,
+    text,
+
+  ghc-options:
+    -Wall
+    -no-hs-main
+    -optl-mexec-model=reactor