With file watching I made a small repl fairly quickly and its a tool that I kept using for longer then a week suggesting its worth keeping around

Its currently a bit of a piece of shit but its competing with dlang.io in my use as is: https://github.com/opendlang/opend/issues/96

(btw dlang.io is consistently degrading someone should do a clean up pass, fix the resharing, shorten the all compiler list, add opend)

rough ideas:

• decrease io by detecting if files change(its a little slow)
• track diffs
• align reported error message possibly using whatever line pragma or just padding if it fails
• pull out har file with a flag
• a/b test different commands