lambda

(lambda <formals> <body>)


Description:

Syntax: <Formals> should be a formal arguments list as described below,

and <body> should be a sequence of one or more expressions.


Semantics: A lambda expression evaluates to a procedure.  The

environment in effect when the lambda expression was evaluated is

remembered as part of the procedure.  When the procedure is later

called with some actual arguments, the environment in which the lambda

expression was evaluated will be extended by binding the variables in

the formal argument list to fresh locations, the corresponding actual

argument values will be stored in those locations, and the expressions

in the body of the lambda expression will be evaluated sequentially in

the extended environment.  The result(s) of the last expression in the

body will be returned as the result(s) of the procedure call.


       (lambda (x) (+ x x))      =>  a procedure

       ((lambda (x) (+ x x)) 4)  =>  8


       (define reverse-subtract

         (lambda (x y) (- y x)))

       (reverse-subtract 7 10)         =>  3


       (define add4

         (let ((x 4))

           (lambda (y) (+ x y))))

       (add4 6)                        =>  10


<Formals> should have one of the following forms:


(<variable1> ...)

     The procedure takes a fixed number of arguments; when the

     procedure is called, the arguments will be stored in the bindings

     of the corresponding variables.


<variable>

     The procedure takes any number of arguments; when the procedure is

     called, the sequence of actual arguments is converted into a newly

     allocated list, and the list is stored in the binding of the

     <variable>.


(<variable1> ... <variablen> . <variablen+1>)

     If a space-delimited period precedes the last variable, then the

     procedure takes n or more arguments, where n is the number of

     formal arguments before the period (there must be at least one).

     The value stored in the binding of the last variable will be a

     newly allocated list of the actual arguments left over after all

     the other actual arguments have been matched up against the other

     formal arguments.


Arguments:


Returns: boolean


Examples:

((lambda x x) 3 4 5 6)          =>  (3 4 5 6)

((lambda (x y . z) z) 3 4 5 6)  =>  (5 6)



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