samdphillips

#lang racket/base

#|

Three color LED connected to RPi GPIO pins 2 3 4.

The process is pretty straightforward.

1. Use FFI to get open and mmap /dev/gpiomem
2. Use FFI ptr-ref and ptr-set! to change the gpio registers

dvanhorn

#lang racket

;; A CPS interpreter for a CBV language written in syntax-rules

;; e ::= 'd          literal
;;    |  x           variable
;;    |  (e e)       application
;;    |  (λ (x) e)   abstraction

;; (eval e) interprets e in an environment

Metaxal

#lang racket

;; License: [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0) or
;;          [MIT license](http://opensource.org/licenses/MIT) at your option.

(require racket/gui/base
         pict)

(define line-width-init 1)

samdphillips

#lang racket/base

(struct %class  [parent ivars methods] #:transparent)
(struct %object [class ivars] #:transparent)

(define (new class vals)
  (%object class vals))

(define (send obj method-name args)
  (define method (lookup-method (object-class obj) method-name))

katef

#!/usr/bin/awk -f

# This program is a copy of guff, a plot device. https://github.com/silentbicycle/guff
# My copy here is written in awk instead of C, has no compelling benefit.
# Public domain. @thingskatedid

# Run as awk -v x=xyz ... or env variables for stuff?
# Assumptions: the data is evenly spaced along the x-axis

# TODO: moving average

jackfirth

Lessons in Using Continuations

This gist contains examples of how to build different kinds of control flow structures in Racket using macros and continuations. Examples include:

• Early exit from functions using a return statement.
• Early exit from arbitrary expressions using a simple exception system.
• Temporarily interrupting execution in order to check permissions.

samdphillips

Advent of Code 2019 Racket Leaderboard

Proposal Author

Sam Phillips

Background

Advent of Code is a coding contest that takes place December 1st to 25th every year. Everyday a new puzzle is posted to the site. The puzzles form a larger story that is Christmas/Holiday themed. There is a global leaderboard which is pretty competitive. They also allow users to

alex-hhh

#lang racket
(require json racket/draw math/base)

(define (lat-lon->map-point coordinates)
  (match-define (list lon lat _ ...) coordinates)
  (define-values (x y) (values (degrees->radians lon) (asinh (tan (degrees->radians lat)))))
  (list (/ (+ 1 (/ x pi)) 2) (/ (- 1 (/ y pi)) 2)))

(define (draw-polygon dc polygons)
  (define path

spdegabrielle

http://chronos-st.blogspot.com/2007/12/smalltalk-in-one-page.html
http://www.csci.csusb.edu/dick/samples/smalltalk.syntax.html

Formal EBNF Specification of Smalltalk Syntax

   1. Character = ? Any Unicode character ?;
   2. WhitespaceCharacter = ? Any space, newline or horizontal tab character ?;
   3. DecimalDigit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
   4. Letter = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M"
                      | "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z"

nilp0inter

#lang 2d racket

(require 2d/match)

(define (fizz? n)
  (= 0 (modulo n 5)))

(define (buzz? n)
  (= 0 (modulo n 3)))