greghendershott

-*- mode:org ; mode:visual-line -*-

Hack && Tell 6 Boston

What is a “debugger”?

Specifically a “step debugger”?

A program that runs your program, letting you

• Pause execution (“break”) at steps of its evaluation (“breakpoints”)

greghendershott

Say that /tmp/ex.rkt is

#lang racket
(define x 42)
x

Now:

$ racket
Welcome to Racket v6.10.

greghendershott

#lang racket/base

(require racket/match)

(define (combining xs pred?)
  (let loop ([xs xs])
    (match xs
      [(list* (? pred? this) (? pred? next) more)
       (loop (cons (string-append this next) more))]
      [(cons this more)

greghendershott

(url
 "http"
 #f
 "bttracker.debian.org"
 6969
 #t
 (list (path/param "announce" '()))
 '((info_hash . ";\u001D��x\u000E���S���zc�R�1�")
   (peer_id . "-TR4940-i750j7wqz8tu")
   (uploaded . "0")

greghendershott

#lang racket/base

(define (expensive-or-complicated v)
  v)  ;not really, but for example

(for*/list ([x (in-list '(1 2 3 4))]
            [y (in-value (expensive-or-complicated x))]
            #:unless (odd? y))
  y)
;; '(2 4)

greghendershott

#lang racket/base

(module m racket/base
  (provide (struct-out exn:fail)
           (rename-out [exn-message            exn:fail-message]
                       [exn-continuation-marks exn:fail-continuation-marks])))

(require 'm)

(define e (exn:fail "foo" (current-continuation-marks)))

greghendershott

#lang racket/base

(require racket/match
         net/dns)

(provide validate-address)

(define (validate-address s)
  (match s
    [(regexp "^([^@]+)@(.+)$" (list _ user domain))

greghendershott

#lang racket/base

(require racket/format
         racket/list
         racket/match
         racket/trace)

(provide (all-defined-out)
         (all-from-out racket/trace))

greghendershott

modified   index.rkt
@@ -12,12 +12,14 @@
           (for-label racket/syntax))
 @(define evaluator
    (parameterize ([sandbox-output 'string]
-                  [sandbox-error-output 'string])
+                  [sandbox-error-output 'string]
+                  [sandbox-memory-limit 100])
      (make-evaluator 'racket)))
 

greghendershott

;; A fairly simple Racket program like this:
(module m racket/base
  (define (f xs)
    (for/list ([x (in-list xs)])
      (add1 x)))
  (f '(1 2 3 4)))

;; Fully expanded with:
;;
;; (println (syntax->datum (expand (with-input-from-file "foo.rkt" read-syntax))))