feat(Makefile): add stack support, default to cabal

Author: rasheedja

Makefile

@@ -1,5 +1,10 @@
 HS_FILES := $(shell git ls-files '*.hs')
 
+# BUILD_TOOL selects the Haskell build tool: cabal (default) or stack.
+BUILD_TOOL ?= cabal
+
+# --- Shared ---
+
 .PHONY: format
 format:
 	@test -n "$(HS_FILES)" || { echo "No tracked .hs files found"; exit 0; }
@@ -10,6 +15,8 @@ format-check:
 	@test -n "$(HS_FILES)" || { echo "No tracked .hs files found"; exit 0; }
 	fourmolu -m check $(HS_FILES)
 
+# --- Cabal ---
+
 .PHONY: cabal-check
 cabal-check:
 	cabal check
@@ -18,26 +25,71 @@ cabal-check:
 cabal-update:
 	cabal update
 
-.PHONY: configure
-configure:
+.PHONY: cabal-configure
+cabal-configure:
 	cabal configure --enable-tests --enable-benchmarks --disable-documentation $(CABAL_CONFIGURE_FLAGS)
 	cabal build --dry-run
 
-.PHONY: deps
-deps:
+.PHONY: cabal-deps
+cabal-deps:
 	cabal build --only-dependencies
 
-.PHONY: build
-build:
+.PHONY: cabal-build
+cabal-build:
 	cabal build all
 
-.PHONY: test
-test:
+.PHONY: cabal-test
+cabal-test:
 	cabal test all
 
-.PHONY: docs
-docs:
+.PHONY: cabal-docs
+cabal-docs:
 	cabal haddock all --disable-documentation
 
+.PHONY: cabal-ci
+cabal-ci: format-check cabal-check cabal-update cabal-configure cabal-deps cabal-build cabal-test cabal-docs
+
+# --- Stack ---
+
+.PHONY: stack-update
+stack-update:
+	stack update
+
+.PHONY: stack-deps
+stack-deps:
+	stack build --only-dependencies --test --no-run-tests
+
+.PHONY: stack-build
+stack-build:
+	stack build
+
+.PHONY: stack-test
+stack-test:
+	stack test
+
+.PHONY: stack-docs
+stack-docs:
+	stack haddock --no-haddock-deps
+
+.PHONY: stack-ci
+stack-ci: format-check stack-update stack-deps stack-build stack-test stack-docs
+
+# ── Generic (delegates to BUILD_TOOL) ────────────────────────────────
+
+.PHONY: update
+update: $(BUILD_TOOL)-update
+
+.PHONY: deps
+deps: $(BUILD_TOOL)-deps
+
+.PHONY: build
+build: $(BUILD_TOOL)-build
+
+.PHONY: test
+test: $(BUILD_TOOL)-test
+
+.PHONY: docs
+docs: $(BUILD_TOOL)-docs
+
 .PHONY: ci
-ci: format-check cabal-check cabal-update configure deps build test docs
+ci: $(BUILD_TOOL)-ci