If my time at Facebook has taught me anything, it's that using an untyped language is pennywise and pound foolish. Whatever time you save in the short term, you

If my time at Facebook has taught me anything, it's that using an untyped language is pennywise and pound foolish. Whatever time you save in the short term, you're going to pay back 100x in the long term. FB devs wrote millions of lines of PHP/Hack code when it was untyped, and then it gradually became more and more typed, and they had to keep modifying the entire codebase with various elaborate schemes so that it sort of complies with increasingly strict type checking. A lot of that was inserting compiler directives to say "ignore type errors on the next line." That built up tech debt which eventually had to be dealt with, and doing that is soooo much more difficult than writing typed code in the first place.