Einar Høst

Computer at NRK

Einar W. Høst is a computer at NRK, the Norwegian public broadcaster. He thinks that programs should be written for people to read and also for machines to laugh at. He has a PhD in Computer Science from the University of Oslo.

Past Activities

Einar Høst
Code Mesh LDN 2018
09 Nov 2018
14.20 - 15.05

A PostScript to Functional Geometry

Peter Henderson's 1982 "Functional Geometry" is a classic paper that shows the beauty and power of functional representation. Using functions to represent pictures, Henderson defines a small set of combinators to create a replica of Escher's recursive tessellation "Square Limit". It's a nice kata for functional programmers.

However, you could also implement Henderson's combinators in concatenative languages, which excel at composition! In this talk, Einar shows us how. For choice of language, Einar turned to PostScript, a proven and battle-worn concatenative language that has been on the plateau of productivity for decades. It's also rather good for drawing. With one neat trick, values on the stack can be captured inside an executable array, to simulate closures. And the rest is easy.


Learn how to do functional programming in a vintage concatenative language.