Nice list, and overlaps a lot with my &quot;Languages to try one day&quot; Post-it note (though I have Elixir instead of Erlang). And I&#x27;d never heard of Forth - amazing what I learn!<p>My current toolbox is:<p>Professional level: PHP, databases, frontend development (but haven&#x27;t picked a JS framework due to choice paralysis)<p>Experience of: C, Python, Matlab, Fortran77, Prolog (my favourite, most mind-bending experience yet. Magic!)<p>I tried learning about monads recently. <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=UvD1VjRvGIk" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=UvD1VjRvGIk</a> made sense (I was nodding my way through) but I kinda missed what a monad was - this just seemed common sense that my languages didn&#x27;t allow :)<p>Thanks, you&#x27;ve inspired me to play.