tcdowney’s gists

tcdowney / atom?.ss

Created January 8, 2013 16:28

Definition for atom? for The Little Schemer.

tcdowney / lat?.scm

Created January 9, 2013 15:58

Definition for lat? for The Little Schemer. #myversion

tcdowney / member?.scm

Created January 9, 2013 18:10

The definition for member? for The Little Schemer. Returns #t if the first argument (an atom) is found in the second argument (a list of atoms).

	(define member?
	(lambda (a lat)
	(cond
	((null? lat) #f)
	(else (or (eq? (car lat) a) (member? a (cdr lat)))))))

tcdowney / free?.scm

Created January 21, 2013 02:12

Scheme snippet that returns true if the variable is a free variable in the expression. Taken from C311 notes and uses pmatch library.

	(define free?
	(lambda (y e ce)
	(pmatch e
	[,x (guard (symbol? x)) (and (eq? x y) (not (memq y ce)))]
	[(lambda (,x) ,body) (free? y body (cons x ce))]
	[(,rator ,rand) (or (free? y rator ce)(free? y rand ce))])))

tcdowney / ds_gyro_read.c

Last active December 12, 2015 00:39

	void ds_gyro_read(uint8_t* pBuffer, uint8_t ReadAddr, volatile uint16_t NumByteToRead) {
	if (NumByteToRead > 0x01) {
	ReadAddr \|= (uint8_t)(0x80 \| 0x40); // If sending more that one byte set multibyte commands
	}
	else {
	ReadAddr \|= (uint8_t) (0x80); // Else just set the read mode
	}

	GYRO_CS_LOW();
	//GPIO_ResetBits(GPIOE, GPIO_Pin_3);

tcdowney / primeperms.rb

Last active August 29, 2015 14:00 — forked from baweaver/primeperms.rb

Use the sieve :)

	def eratosthenes(n)
	nums = [nil, 1, *2..n]
	(2..Math.sqrt(n)).each do \|i\|
	(i**2..n).step(i){\|m\| nums[m] = nil} if nums[i]
	end
	nums
	end

	primes_to_million = eratosthenes(1_000_000)

tcdowney / missing_translations.rb

Created October 10, 2014 02:39

Missing Translations RSpec Matcher

	# spec/support/missing_translations.rb
	require 'rspec/expectations'

	RSpec::Matchers.define :have_missing_translations do

	match do \|actual\|
	missing_i18n_js = /\[missing ".*" translation\]/
	missing_i18n_ruby = /class="translation_missing"/
	!!(actual.body.match(missing_i18n_ruby) \|\| actual.body.match(missing_i18n_js))
	end

tcdowney / raspbian-sd-longetivity.sh

Created June 3, 2018 03:13

Raspbian SD Longetivity Commands

	# Inspired by https://raspberrypi.stackexchange.com/questions/169/how-can-i-extend-the-life-of-my-sd-card
	# Gonna see if I can get by with just disabling swap for now

	# Disable SWAP
	sudo dphys-swapfile swapoff && \
	sudo dphys-swapfile uninstall && \
	sudo update-rc.d dphys-swapfile remove

tcdowney / rename_ga.rb

Created May 21, 2019 01:55

Hacky rename of Intro to Graduate Algorithms videos to get sorted correctly on Kindle Fire

	leading_digit_regex = /\d+\s+/
	path = '/Users/tcdowney/Downloads/ga-vids'

	Dir.glob("#{path}/*.mp4") do \|mp4_file\|
	filename = File.basename(mp4_file, File.extname(mp4_file))
	leading_digits = filename.match(leading_digit_regex)[0].to_i
	padded_digits = sprintf('%03d', leading_digits)
	padded_filename = filename.gsub(leading_digits.to_s, padded_digits)
	#puts padded_filename + File.extname(mp4_file)
	File.rename(mp4_file, padded_filename + File.extname(mp4_file))

tcdowney / keybase.md

Created October 6, 2019 05:31

I hereby claim:

I am tcdowney on github.
I am tcdowney (https://keybase.io/tcdowney) on keybase.
I have a public key whose fingerprint is 90C8 2606 77B1 FF63 34C1 1DEE 301B 9993 40D5 E292

To claim this, I am signing this object:

Tim Downey tcdowney