Partial Evaluation

Partial evaluation is the technique of evaluating as much of a program as possible at compile time, leaving only data-dependent computations to runtime.

• Constant folding: &pi · 2 &rarr 6.28

• Operations involving special constants: x · 1 &rarr x

• Simplification of if statements when the test is constant allows removal of interpretation.

• Method dispatch in OOP when type is known.
  (draw x) &rarr (draw-circle x)

• Strong typing: eliminates type testing at runtime if types are known.

• Inline expansion: eliminates function call overhead, allows further optimization.

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