branneman

#lang racket

; syntax: literals and manipulation
(syntax (if x (list "true") #f))
#'(if x (list "true") #f)
(syntax->list #'(if x (list "true") #f)) ; list of syntax objects (only first level)
(syntax->datum #'(if x (list "true") #f)) ; discards metadata from nested syntax
(datum->syntax #f '(if x (list "true") #f)) ; creates syntax without metadata

; defining functions for use at compile time

branneman

Automate backups: Nextcloud to S3

Assumptions

• Disk space: at least 3× the size of the /var/www/nextcloud directory is available on /var/backups
• Nextcloud is installed into /var/www/nextcloud as user www-data
• AWS cli is installed and configured with credentials
• mysqldump is installed
• rsync is installed

Setup

branneman

[
  {
    "id": 1,
    "radical": "一",
    "pinyin": "yī",
    "english": "one",
    "strokeCount": 1
  },
  {
    "id": 2,

branneman

(ns main (:gen-class))

;; Snake :: [[int int]…]
;;  vector of x,y tuples
;;  head is first, tail is last

;; out-of-bounds? :: (int int int) -> bool
;;  grid-size is 1-indexed, x+y are 0-indexed
(defn out-of-bounds? [grid-size x y]
  (or (neg? x) (neg? y) (>= x grid-size) (>= y grid-size)))

branneman

List of all Clojure Predicate functions

A predicate function returns a boolean true or false, and it's name ends with a ?. Ran against Clojure 1.10.0.

({:ns clojure.string,
  :predicates
  ({:fn ends-with?, :arglists ([s substr])}
   {:fn starts-with?, :arglists ([s substr])}
   {:fn includes?, :arglists ([s substr])}

branneman

const wrapPromise = fn => (...args) =>
  new Promise(resolve => setTimeout(
    () => resolve(fn(...args)),
    Math.floor(Math.random() * 1500) + 250)
  )
const upper = wrapPromise(str => str.toUpperCase())
const underline = str => `__${str}__`
const exclamate = wrapPromise(str => str + '!')

// Util: Create promise chain

branneman

//
// Tight coupling from A to B  => A needs B to be defined, callable and adhere to an interface
// No coupling from B to A     => B does not need A in any way (pure fn)
//
function a() { b() }
function b() {}
a()

//
// No coupling from A to B         => A and B work independently,

branneman

Run Debian as docker container

Setup

Start a container in detached mode:

docker run -dit --name deb -e "LANG=C.UTF-8" -w "/root" debian:latest bash

Connect to it and do initial setup:

branneman

const { curryN, curry } = require('./curry') // https://gist.github.com/branneman/4ffb7ec3fc4a2091849ba5d56742960c

// Typechecks
const isUndef = x => typeof x === 'undefined'
const isNull = x => x === null
const isBool = x => typeof x === 'boolean'
const isNum = x => typeof x === 'number' && isFinite(x)
const isInt = x => typeof x === 'number' && isFinite(x) && Math.floor(x) === x
const isStr = x => typeof x === 'string'
const isArr = x => Array.isArray(x)

branneman

'use strict'

const curryN = (() => {
  const isPlaceholder = x => x['@@functional/placeholder'] === true
  const filterPlaceholders = xs => xs.filter(x => isPlaceholder(x))
  const filterValues = xs => xs.filter(x => !isPlaceholder(x))

  return (arity, fn, accIn = []) => (...args) => {
    const accOut = accIn.slice()