build

name	build
description	Build the mtg-pure Haskell project with cabal/GHC. Use whenever you need to compile the project, verify a change type-checks, do a clean build, or diagnose a build failure. Covers the PowerShell/Windows setup and the ToObjectN code-generation prestep (which you should NOT run proactively — it forces a long recompile).

Build mtg-pure

Toolchain is installed: GHC 9.10.3 + cabal 3.16 in C:\ghcup\bin.

Use PowerShell (not Git Bash)

Run build commands with the PowerShell tool. Not for caching reasons — both shells reuse the compiled .hi/.o cache equally (see below). PowerShell wins on everything around the build: Git Bash mangles Windows paths (/c/...), sets HOME, and reorders PATH, which bites the sh.exe/configure steps, runghc codegen, and log encoding.

Build

cabal build

• First build compiles the whole dep tree + generated ToObjectN modules — many minutes. Run it in the background and check the log.
• Incremental rebuilds are very fast. cabal reuses cached .hi/.o object code. A message like mtg-pure ... (configuration changed) is not a recompile — it's just a seconds-long reconfigure (rewrites setup-config / plan.json); your compiled objects are reused untouched. Editing a file ("touch") only recompiles the modules that actually changed.
• The configuration changed fingerprint is per-environment, so it ping-pongs between a tool shell and an interactive cmd.exe. Harmless — each side just pays one reconfigure, never a recompile.

Presteps (only if they fail)

1. ToObjectN code — assume it is already up to date; do NOT regenerate proactively. Files under src/MtgPure/Model/Object/ToObjectN/Instances* are git-ignored + generated. Their content changes only when the ObjectN/OT machinery changes (rare), but regenerating rewrites ~130 files' timestamps, which forces cabal to recompile every one of them — many minutes — even though nothing actually changed. So leave them alone by default.

   Only regenerate when an independent build error clearly requires it: the generated files are missing entirely (Instances.hs absent → build fails), or a build error points at a stale/missing ToObject instance after you changed the ObjectN/OT types (see regen-object-code). Then:

   New-Item -ItemType Directory -Force src\MtgPure\Model\Object\ToObjectN\Instances | Out-Null
   Set-Location src; runghc MtgPure/Model/Object/ToObjectN/CodeGen.hs; Set-Location ..
   

2. cabal update once if the solver says unknown package: ... (empty Hackage index).

3. If ./configure fails with [Cabal-8011] (needs Unix toolchain), put sh.exe on PATH: prepend C:\Program Files\Git\usr\bin to $env:Path.

Diagnose failures

• cabal build 2>&1 | Out-File -Encoding utf8 "$env:TEMP\mtg-build.log" (utf8, or the log reads as garbage), then grep error:|Failed to build|Cabal-[0-9].
• Dependency-version / new-warning failures → see update-cabal-toolchain.

Run after building

REPL: cabal repl. Tests/demo are main<Name> entry points — see run-tests.