Iverson bracket: APL (programming language), Donald Knuth, Kronecker delta, Indicator function, Sign Heaviside step Trichotomy (mathematics)

FP (Programming Language): programming language, John Backus, Function level programming, APL FL J language

Cat (programming Language): Stack oriented programming language, Joy language), Function composition, Lambda...

Indent style: Indentation, C (programming language), Curly bracket Programming language, style, Apple...