Simula 67 had separate value and reference assignment operators

Simula 67 had two notations for assignment, namely, := for value assignment of basic types and :- for reference assignment of user-defined types.

Source: http://blog.greaterthanzero.com/post/58482859780/c-and-the-culture-of-complexity
added 2013-08-24T00:20:07Z by anders

λ-calculus core

At it’s core, the lambda calculus contains only: variable references, single-argument anonymous functions and function calls.

Source: Church-encoded numbers, lists, booleans, conditionals with fixed-point recursion in Scheme
added 2012-03-15T15:43:43Z by anders