Partial Evaluation[Neil D. Jones, Carsten K. Gomard, and Peter Sestoft, Partial Evaluation and Automatic Program Generation, Prentice-Hall, 1993.]

Partial evaluation specializes a function with respect to arguments that have known values. Given a program P(x, y) where the values of variables x are constant, a specializing function mix transforms P(x, y) &rarr P_x(y) such that P(x, y) = P_x(y) for all inputs y. P_x(y) may be shorter and faster than P(x, y) . We call x static data and y dynamic data. .

Partial evaluation involves:

• precomputing constant expressions involving x,
• propagating constant values,
• unfolding or specializing recursive calls,
• reducing symbolic expressions such as x * 1, x * 0, x + 0, (if true S₁ S₂).

Partial evaluation improves execution time by a (possibly large) constant factor, by increasing the binding between a program and its execution environment.

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