Eager evaluation

In eager evaluation an expression is evaluated as soon as it gets bound to a variable. This is generally more efficient as a low-level strategy in simple programming languages, as it removes the need to build and managed intermediate data structures representing unevaluated expressions.

The low-level optimisation of forced eager evaluation prevents the higher-level optimisations and greater expressiveness that can be obtained from lazy evaluation in more sophisticated programming languages, which generally allow the implementation of both lazy and eager semantics.

See also: speculative execution[?].