# Lambda abstraction

A

**lambda abstraction** is an abstract lambda expression. It is expressed in the language of

lambda calculus. A lambda abstraction is to a

functional programming language such as

Scheme what pseudo-code is to an

imperative programming language.

More specifically, a lambda abstraction is a lambda expression with no free variables: each its variables is bound by some lambda. E.g.

- f (f (f x))

is a concrete lambda expression, whereas

- λf. λx. f (f (f x))

is an abstract lambda expression.

For example, λ could stand for 'for each', 'for some', or 'there is'. In this case, the expression could stand for a 'logic proposition'.