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The scheme environment: continuations

Continuations are also a fairly old concept. Their importance became evident in the pioneering work of Christopher Strachey, Peter Landin, John Reynolds, and others who during the late 1960's were using lambda calculus as a formal tool to describe the semantics of Algol 60 and other programming languages [4, 5]. Carl Hewitt borrowed the concept from this work on formal semantics, giving it prominence in his message-passing model of computation known as actors. Continuations were carried over into Scheme, which Guy Steele and Gerry Sussman invented as a concrete implementation of actors.