Add `make watch` command for automatic rebuilding. (#442)
Add `make watch` command for automatic rebuilding. (#442)

`make watch` invokes `stack build $(STACK_FLAGS) --file-watch`, which
watches for source file changes and automatically rebuilds.
google-research/dex-lang,google-research/dex-lang,google-research/dex-lang,google-research/dex-lang,google-research/dex-lang,google-research/dex-lang