soegaard

#lang racket
(provide tagged-begin)

;;; INTRODUCTION

; This is a little macro that resembles the Common Lisp tagbody construct
;  <http://www-2.cs.cmu.edu/Groups/AI/html/hyperspec/HyperSpec/Body/speope_tagbody.html#tagbody>
; See also "Applications of Continuations" of Daniel P. Friedman.

;;; MOTIVATION

soegaard

#lang racket
(define-syntax (my-for/first stx)
  (syntax-case stx ()
    [(_ (for-clause ...) . defs+exprs)
     (syntax/loc stx
       (let-values ([(val _)
                     (for/fold ([val #f] [stop? #f])
                       (for-clause ... #:unless stop?)
                        (begin 
                          (define x (let () . defs+exprs))

soegaard

(for/fold ([val #f] [stop? #f])
    (#:unless stop? 
     [x '(1 3 5 7 4 9 6)]
     #:when (even? x))
    (values x #t))

soegaard

#lang typed/racket
(require/typed typed/racket
               [integer-sqrt/remainder (Natural Natural -> Natural)])
integer-sqrt/remainder

----

racket-math/racket/collects/racket/contract/private/blame.rkt:89:0: integer-sqrt/remainder: broke its contract
  promised a procedure that accepts 2 mandatory arguments without any keywords, produced: #<procedure:integer-sqrt/remainder>
  in: (recursive-contract

soegaard

;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname pacman) (read-case-sensitive #t) (teachpacks ((lib "image.ss" "teachpack" "2htdp") (lib "universe.ss" "teachpack" "2htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "image.ss" "teachpack" "2htdp") (lib "universe.ss" "teachpack" "2htdp")))))

;;; Inspired by http://www.khanacademy.org/cs/chompy-and-friends/882986876

(define PACMAN-RADIUS 50)

(define pacman 
  (overlay/offset

soegaard

#lang racket
(define-syntax (foo stx)
  (syntax-case stx ()
    [(foo x)
     (let ([a (+ 1 2)])
       (with-syntax ([a a])
         #'(+ x a)))]))

(foo 39)

soegaard

#lang racket/base

(define m (- (expt 2 32) 5))
(define a (- (expt 2 32) 333333333))

(define rand
  (let ([xn 1])
    (λ ()
      (set! xn (modulo (* a xn) m))
      xn)))

soegaard

#lang racket

;;;
;;; How to take a screenshot on OS X
;;;   -- Jens Axel Søgaard

;;;
;;; This gist illustrates how to work with OS X
;;; system calls in order to take a screen shot.
;;;

soegaard

#lang racket
;;;
;;; How to take a screenshot on OS X
;;;   -- Jens Axel Søgaard
;;;
;;; This gist illustrates how to work with OS X
;;; system calls in order to take a screen shot.
;;;

(require racket/draw

soegaard

#lang racket/base

(require ragg/examples/simple-line-drawing/lexer
         ragg/examples/simple-line-drawing/grammar
         syntax/parse
         (for-syntax syntax/parse)
         (for-syntax racket/base))

(define-syntax (define-datums stx)
  (syntax-parse stx