CLU, a programming language created at MIT by Barbara Liskov [1] in 1974-1975, was the first language which had iterators.

Syntax of CLU was based on Pascal, but strongly simplified.

CLU uses a concept called a "cluster" which is a slight generalisation of "modules" as seen in Modula-2, early Ada, etc. This is about the closest you can get to object-oriented programming without actually being there.

Ruby borrowed many concepts from CLU and has similar syntax.

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