The eta rewrite rule

The Order of Evaluation - slide 12 : 26

An eta conversion lifts certain function calls out of a lambda convolute

A function f, which only passes its parameters on to another function e, can be substituted by e

(lambda(x) (e x)) <=> e provided that x is not free in the expression e

Legal conversion:

Expression	Converted Expression
(lambda (x) (square x))	square

Illegal conversion:

Expression	Converted Expression
(lambda(x) ((lambda(y) (f x y)) x))	(lambda(y) (f x y))