Build Agda to JavaScript using the GHC 9.6 JavaScript backend

build-agda-js.sh

#!/bin/bash
set -eo pipefail

# 1. Build GHC with JavaScript backend
# https://gitlab.haskell.org/ghc/ghc/-/wikis/javascript-backend/building

# 2. Get Agda source
git clone --depth=1 git@github.com:agda/agda.git agda
cd agda

# 3. Ensure emscripten has the port for zlib
mkdir _zlib
wget https://raw.githubusercontent.com/madler/zlib/master/test/example.c -O _zlib/example.c
emcc -s USE_ZLIB=1 _zlib/example.c -o _zlib/example.js
node _zlib/example.js
rm -r _zlib

# 4. Patch Agda source
mkdir _patches
cat <<'EOF' > '_patches/0001-Set-build-type-Simple.patch'
From d21e6ca5c1ef08901468b3d820cc8c25b875bb3e Mon Sep 17 00:00:00 2001
From: Wen Kokke <wenkokke@users.noreply.github.com>
Date: Thu, 8 Jun 2023 18:12:59 +0100
Subject: [PATCH 1/2] Set build-type: Simple

---
 Agda.cabal | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Agda.cabal b/Agda.cabal
index 93e9180b7..df306467b 100644
--- a/Agda.cabal
+++ b/Agda.cabal
@@ -1,7 +1,7 @@
 cabal-version:   2.4
 name:            Agda
 version:         2.6.4
-build-type:      Custom
+build-type:      Simple
 license:         LicenseRef-OtherLicense
 license-file:    LICENSE
 copyright:       (c) 2005-2023 The Agda Team.
--
2.40.1

EOF
git apply _patches/0001-Set-build-type-Simple.patch

cat <<'EOF' > '_patches/0002-Remove-use-of-Template-Haskell.patch'
From f4f19b764cdac3ae8ff3a3e61b88c2c6032aa3a2 Mon Sep 17 00:00:00 2001
From: Wen Kokke <wenkokke@users.noreply.github.com>
Date: Thu, 8 Jun 2023 18:19:45 +0100
Subject: [PATCH 2/2] Remove use of Template Haskell

---
 Agda.cabal                     |  1 -
 src/full/Agda/VersionCommit.hs | 16 +---------------
 2 files changed, 1 insertion(+), 16 deletions(-)

diff --git a/Agda.cabal b/Agda.cabal
index df306467b..e9de1c59b 100644
--- a/Agda.cabal
+++ b/Agda.cabal
@@ -389,7 +389,6 @@ library
     , exceptions           >= 0.8       && < 0.11
     , filepath             >= 1.4.2.1   && < 1.5
     , ghc-compact          == 0.1.*
-    , gitrev               >= 1.3.1     && < 2.0
     -- hashable 1.2.0.10 makes library-test 10x
     -- slower. The issue was fixed in hashable 1.2.1.0.
     -- https://github.com/tibbe/hashable/issues/57.
diff --git a/src/full/Agda/VersionCommit.hs b/src/full/Agda/VersionCommit.hs
index 2753f8ed2..652cb3e83 100644
--- a/src/full/Agda/VersionCommit.hs
+++ b/src/full/Agda/VersionCommit.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE CPP             #-}
-{-# LANGUAGE TemplateHaskell #-}

 #if __GLASGOW_HASKELL__ >= 900
 {-# OPTIONS_GHC -Wno-overlapping-patterns #-}
@@ -7,8 +6,6 @@

 module Agda.VersionCommit where

-import Development.GitRev
-
 import Agda.Version

 versionWithCommitInfo :: String
@@ -16,15 +13,4 @@ versionWithCommitInfo = version ++ maybe "" ("-" ++) commitInfo

 -- | Information about current git commit, generated at compile time
 commitInfo :: Maybe String
-commitInfo
-  | hash == "UNKNOWN" = Nothing
-  | otherwise         = Just $ abbrev hash ++ dirty
-  where
-    hash = $(gitHash)
-
-    -- Check if any tracked files have uncommitted changes
-    dirty | $(gitDirtyTracked) = "-dirty"
-          | otherwise          = ""
-
-    -- Abbreviate a commit hash while keeping it unambiguous
-    abbrev = take 7
+commitInfo = Nothing
--
2.40.1

EOF
git apply _patches/0002-Remove-use-of-Template-Haskell.patch

# 5. Build Agda
mkdir _build
cabal v2-install \
  --ghc-option=-O2 \
  -f+optimise-heavily \
  --with-ghc=$(which javascript-unknown-ghcjs-ghc) \
  --with-ghc-pkg=$(which javascript-unknown-ghcjs-ghc-pkg) \
  --with-hsc2hs=$(which javascript-unknown-ghcjs-hsc2hs) \
  --with-gcc=$(which emcc) \
  --with-ld=$(which emcc) \
  --with-strip=$(which emstrip) \
  --installdir=_build \
  --install-method=copy \
  --overwrite-policy=always

# 6. Minify with esbuild
npx esbuild --bundle --minify --platform=node --target=node18 --tree-shaking=true _build/agda.js --outfile=_build/agda.min.js