Some time ago on HN there was Facebook exploit posted where it was possible to track your friends. All this was possible mainly because lacking real types the o

Some time ago on HN there was Facebook exploit posted where it was possible to track your friends. All this was possible mainly because lacking real types the only stable interface becomes string and everything becomes stringly typed. Static types are not only strings and numbers and static types are about something more than typed variables. Too many times have I run into situation when I call some API in dynamic language and have absolutely no idea what can I do with the thing being returned. In dynamic language I have to either read the docs (hoping they are good) or introspect in a REPL, IDE won't help. And In Python world, the wrapper library method I'm calling forwards kwargs to some underlying library and I have absolutely no idea what can I pass without getting familiar with the underlying library. Dynamically typed abstractions are very prone to leaking.