To pick up the basics of a language similar to one you already know? Sure. I used this site to write something in Nim just a few days ago.

Do I know the conventions or idioms? No. Do I know the advanced features of Nim? I sincerely doubt it. But I know Python, and seeing the syntax written out is enough for me to correct my informed guesses in how to write it.

I doubt I could use it to pick up Haskell or a language whose paradigm I was unfamiliar with though.