There is, in fact, an homology between the l-calculus for sequential programs and the p-calculus for concurrent processes, so we have the l-calculus and the p-calculus. Here, you see, we describe functions, here we describe processes. The basic binding operation is functional application, while here it is parallel composition; b-reduction is the basic computation of rule in the functional paradigm. Communication is the basic computational ingredient in the concurrent world. LISP, ML, Haskell are functional languages based on l-calculus, and PICT is a language based on the p-calculus.

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