PPT Slide
In the lambda calculus, you define functions using expressions such as
Lisp borrowed the ?, changed it to ‘lambda’ for utility functions that don’t have names.
( lambda ( <args> ) <body> )
is the definitions of a nameless function to be used by another function
( ( lambda ( x ) ( + 2 x ) ) 3 )
( ( lambda ( x y ) ( + x y ) ) 2 3 )
( mapcar #’( lambda ( x ) ( + x x) ) ’( 4 1 3 ) )