Improved makefile

Makefile now only builds if there as been any changes to the relevant files.
`make spec` will build `bin/spec` (if not otherwise specified) and run it; if it were to be run again with no changes to any files made, `bin/spec` will be reused.
`make help` also looks much much better.

Author: Jens

.gitignore

@@ -1,7 +1,7 @@
 *~
 
-# Files created by sentry
-*sentry*
+# Local files
+/local/
 
 # Build artifacts and dependencies
 /lib/
@@ -10,7 +10,9 @@
 
 # Crystal generated docs
 /docs/
+
 # The myst executable
 /myst
+
 # DWARF file from compiling on macOS
-/myst.dwarf
+*.dwarf

Makefile

@@ -1,22 +1,122 @@
-.PHONY: help clean spec mystspec
+# Because env `SHELL` might be 
+# some extremely weird shell
+SHELL = bash
 
-spec:      ## Runs all specs
-	crystal spec
-	crystal run src/myst_cli.cr -- spec/myst/spec.mt
+# Parse makefiles named *.mk in the dir `local`
+# for local extra makefile targets if wanted.
+# It is smart to set MYSTBUILD to your myst dev-build there
+-include local/*.mk
 
-myst-spec: ## Runs just the in-language specs
-	crystal run src/myst_cli.cr -- spec/myst/spec.mt
-	
-build:     ## Builds myst into an executable
-	shards build
+# https://www.gnu.org/software/make/manual/html_node/One-Shell.html
+.ONESHELL:
 
-check:     ## Runs all crystal specs
-	crystal spec/
+# The docs says i should do this
+.SUFFIXES: .cr .mt
 
-clean:     ## Cleans (deletes) docs and executables
-	rm -rf docs
-	rm bin/*
+MYST_CLI = src/myst_cli.cr
 
-# https://gist.github.com/prwhite/8168133 "Help target"
-help:      ## Show this help.
-	@fgrep -h "##" $(MAKEFILE_LIST) | fgrep -v fgrep | sed -e 's/\\$$//' | sed -e 's/##//'
+MYST_INTERPRETER_SPEC = spec/all_spec.cr
+MYST_IN_LANG_SPEC 		= spec/myst/spec.mt
+
+SOURCE_FILES := $(shell find src    -type f -name '*.cr')
+SPEC_FILES   := $(shell find spec   -type f -name '*.cr' -o -name '*.mt')
+STDLIB_FILES := $(shell find stdlib -type f -name '*.mt')
+ALL_FILES    := $(SPEC_FILES) $(STDLIB_FILES) $(SOURCE_FILES)
+
+INSTALL_LOCATION ?= /usr/local/bin/myst
+MYSTBUILD				 ?= myst
+
+O ?= bin
+
+verbose ?= true
+
+# If another default is intentionally wished for,
+# set it in local/*.mk, like this:
+# .DEFAULT_GOAL = goal
+# 
+.DEFAULT_GOAL ?= spec
+
+verbose_log = $(if $(subst false,,$(verbose)), $(info $(1)))
+
+.PHONY: spec
+spec: $(O)/myst $(O)/spec ## Runs all specs
+	@$(call verbose_log,Running interpreter spec)
+	$(O)/spec
+	@$(call verbose_log,Running in-language spec)
+	$(O)/myst $(MYST_IN_LANG_SPEC)
+
+myst-spec: $(O)/myst ## Runs just the in-language specs
+	$(O)/myst $(MYST_IN_LANG_SPEC)
+
+.PHONY: install
+install: $(INSTALL_LOCATION) ## Install myst to INSTALL_LOCATION		
+
+.PHONY: build
+build: $(O)/myst ## Builds myst into an executable
+
+.PHONY: myst-spec_with_build
+myst-spec_with_build: ## Runs the in-language specs with MYSTBUILD
+	$(MYSTBUILD) $(MYST_IN_LANG_SPEC)
+
+$(O)/myst: $(SOURCE_FILES)
+	@$(call verbose_log,Building myst...)
+	@mkdir -p $(O)
+	crystal build -o $(O)/myst $(MYST_CLI)
+
+$(O)/spec: $(ALL_FILES)
+	@$(call verbose_log,Building specs...)
+	@mkdir -p $(O)
+	crystal build -o $(O)/spec $(MYST_INTERPRETER_SPEC)
+
+$(INSTALL_LOCATION): $(SOURCE_FILES)
+	@mkdir -p $(dir $(INSTALL_LOCATION))
+	sudo crystal build --release -o $(INSTALL_LOCATION) $(MYST_CLI)	
+
+.PHONY: clean
+clean: ## Cleans (deletes) docs and executables	
+ifdef O	
+	@[ -f $(O)/myst ] && rm $(O)/myst
+	@[ -f $(O)/spec ] && rm $(O)/spec
+endif
+	@rm -rf docs
+
+# Thanks https://stackoverflow.com/questions/4219255/how-do-you-get-the-list-of-targets-in-a-makefile/26339924#26339924
+define TARGET_LIST =
+$(shell \
+	$(MAKE) -pRrq -f $(MAKEFILE_LIST) : 2>/dev/null | awk -v RS= -F: '/^# File/,/^# Finished Make data base/ {if ($$1 !~ "^[#.]") {print $$1}}' |\
+	sort |\
+	egrep -v -e '^[^[a-zA-Z0-9]]' -e '^$@$$' |\
+	xargs )
+endef
+
+# Used in help target
+list:
+	@echo $(TARGET_LIST)
+
+HELP_INDENTATION 	 ?= 2
+HELP_NAME-DESC_SEP ?= 2
+
+LENGTH_OF_LONGEST_TARGET_NAME = $(shell ruby -e 'puts ARGV.sort_by(&:size)[-1].size' $$(make list))
+
+parse_help = perl -n -e \
+	'if(/^(\S*)?(?=:).*$(HELP_MARK)\s*(.*)/){ \
+		print((" " x $(HELP_INDENTATION)) . "$$1" . (" " x ($(LENGTH_OF_LONGEST_TARGET_NAME) + $(HELP_NAME-DESC_SEP) - length($$1))) . "- $$2\n") \
+	}' $(1) |\
+	sort
+
+# Help target that reads text after two '#'s in a target definition and prints it after the target name
+.PHONY: help
+help: ## Show this help
+	@echo "The main targets are:"
+	@$(call parse_help, $(firstword $(MAKEFILE_LIST))); echo
+	# Iterate through the extra optional makefiles
+	@for makefile in $(wordlist 2, $(words $(MAKEFILE_LIST)), $(MAKEFILE_LIST)); do 
+		echo "Targets defined in $$makefile:"
+			$(call parse_help, $$makefile)
+		echo
+	done
+	@echo "The default target is '$(.DEFAULT_GOAL)'"
+
+define HELP_MARK
+##
+endef

spec/all_spec.cr

@@ -0,0 +1 @@
+require "./**"