APL Demonstration (1975) [video]
As cool as this is, APL has improved a <i>lot</i> in the 34 years since that video was made.  Most notably, these days, APL has `direct functions`, which enable a degree of concision and tacit-programming support unmatched in any other programming language (yes, including Haskell).<p>As a minor taste of the power of direct fns, here&#x27;s a naive implementation of the Fibonacci sequence with one: `fib←{1≥⍵:⍵⋄(∇⍵-1)+∇⍵-2}`