Named let
«Named let» is a variant of
let
that has the form
(let var bindings body)The
<bindings>
and
<body>
are just as in ordinary
let
, except that
<var>
is bound within
<body>
to a procedure whose body is
<body>
and whose parameters are the variables in the
<bindings>
. Thus, one can repeatedly execute the
<body>
by invoking the procedure named
<var>
. For example, the iterative Fibonacci procedure (section 1.2.2) can be rewritten using named
let
as follows:
(define (fib n)
(let fib-iter ((a 1)
(b 0)
(count n))
(if (= count 0)
b
(fib-iter (+ a b) a (- count 1)))))Modify
let->combination
of exercise
4.6
to also support named
let
.