Here's a program that prints the first 10 Fibonacci numbers:
#lang racket
(define (lazy-map f . lsts)
(define flsts (map force lsts))
(if (ormap null? flsts)
null
(cons (apply f (map car flsts))
(lazy (apply lazy-map f (map cdr flsts))
(define fib (cons 1 (cons 1
10 hours ago, Ryan Culpepper wrote:
See SRFI-45 (http://srfi.schemers.org/srfi-45/srfi-45.html) for a
discussion of why lazy is necessary (ie, why force and delay are not
sufficient in practice).
Racket's lazy might (?) be slightly different from the one discussed
there, though. See this
I'm trying to understand how to use (lazy body ...+) to generate an infinite
list.
Would somebody please provide an example or two using it, say for ones and fibs.
Thanks very much.
lb
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Are you sure you're not looking for the racket/stream library instead?
For example:
#lang racket
(require racket/stream)
(define ones (stream-cons 1 ones))
Racket Users list:
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Thanks, Danny.
I am trying to understand how to use promises, in particular for lazy
programming. I know there are various implementations that solve this more
simply: racket/stream and racket/lazy; but I'd like to see how it's done with
the more primitive racket/promise library. It appears
The following program creates four infinite lists and tries to take the
first of each. Only the last expression raises an error.
#lang racket
(require racket/promise)
(define ones (lazy (cons 1 ones)))
(define ones* (delay (cons 1 ones*)))
(car (force ones))
(car (force ones*))
(define twos
See SRFI-45 (http://srfi.schemers.org/srfi-45/srfi-45.html) for a
discussion of why lazy is necessary (ie, why force and delay are not
sufficient in practice).
Racket's lazy might (?) be slightly different from the one discussed
there, though. See this post by Eli for why:
Here's a program that prints the first 10 Fibonacci numbers:
#lang racket
(define (lazy-map f . lsts)
(define flsts (map force lsts))
(if (ormap null? flsts)
null
(cons (apply f (map car flsts))
(lazy (apply lazy-map f (map cdr flsts))
(define fib (cons 1 (cons 1
