Update Makefile (#145)

Quality-of-life improvements.

Author: 9999years

tests/data/simple/Makefile

@@ -1,6 +1,21 @@
-CABAL = cabal \
-		--offline \
-		$(if $(GHC), --with-compiler=$(GHC))
+CABAL_OPTS ?=
+CABAL ?= cabal \
+	--offline \
+	$(if $(GHC), --with-compiler=$(GHC)) \
+	$(CABAL_OPTS)
+
+CABAL_REPL ?= $(CABAL) \
+	--repl-option -fdiagnostics-color=always \
+	-flocal-dev v2-repl lib:test-dev
+
+GHCIWATCH_OPTS ?=
+GHCIWATCH ?= ../../../target/release/ghciwatch \
+	--command "$(CABAL_REPL)" \
+	--before-startup-shell "make my-simple-package.cabal" \
+	--watch src \
+	--watch test \
+	--watch test-main \
+	$(GHCIWATCH_OPTS)
 
 my-simple-package.cabal: package.yaml
 	hpack .
@@ -11,8 +26,12 @@ test: my-simple-package.cabal
 	$(CABAL) test
 	$(CABAL) -flocal-dev build
 	$(CABAL) -flocal-dev test
-	echo ":quit" | $(CABAL) -flocal-dev repl lib:test-dev
+	echo ":quit" | $(CABAL_REPL)
 
 .PHONY: ghci
 ghci: my-simple-package.cabal
-	$(CABAL) -flocal-dev repl lib:test-dev
+	$(CABAL_REPL)
+
+.PHONY: ghciwatch
+ghciwatch:
+	$(GHCIWATCH)