Info Catalog elisp: Lambda Components elisp: Lambda Expressions elisp: Argument List

elisp: Simple Lambda

 
 12.2.2 A Simple Lambda Expression Example
 -----------------------------------------
 
 Consider the following example:
 
      (lambda (a b c) (+ a b c))
 
 We can call this function by passing it to ‘funcall’, like this:
 
      (funcall (lambda (a b c) (+ a b c))
               1 2 3)
 
 This call evaluates the body of the lambda expression with the variable
 ‘a’ bound to 1, ‘b’ bound to 2, and ‘c’ bound to 3.  Evaluation of the
 body adds these three numbers, producing the result 6; therefore, this
 call to the function returns the value 6.
 
    Note that the arguments can be the results of other function calls,
 as in this example:
 
      (funcall (lambda (a b c) (+ a b c))
               1 (* 2 3) (- 5 4))
 
 This evaluates the arguments ‘1’, ‘(* 2 3)’, and ‘(- 5 4)’ from left to
 right.  Then it applies the lambda expression to the argument values 1,
 6 and 1 to produce the value 8.
 
    As these examples show, you can use a form with a lambda expression
 as its CAR to make local variables and give them values.  In the old
 days of Lisp, this technique was the only way to bind and initialize
 local variables.  But nowadays, it is clearer to use the special form
 ‘let’ for this purpose (Local Variables).  Lambda expressions
 are mainly used as anonymous functions for passing as arguments to other
 functions (Anonymous Functions), or stored as symbol function
 definitions to produce named functions (Function Names).
 

Info Catalog elisp: Lambda Components elisp: Lambda Expressions elisp: Argument List