evancz

Focus

A Focus is a way to work with particular parts of a large chunk of data. On the most basic level, it lets you get and set fields of a record in a simple and composable way. This means you could avoid writing special record update syntax and use something that composes much more elegantly.

This API is inspired by the concept of Bidirectional Lenses as described by Nate Foster and seen in a modified form in Haskell as "lenses" and in ClojureScript as "cursors". My personal opinions and understanding comes from this talk by Simon Peyton Jones, discussions with @seliopou, and a basic understanding of Nate Foster's PhD thesis on bidirectional lenses. I chose the name "Focus" for this outline because it is sort of like a lens that only lets you see in one direction.

Here's the pseudocode that describes the basic API:

modul

Tehnix

#!/bin/sh
binaries=(
  awscli
  trash
  tree
  git
  mosh
  tmux
  screen
  zsh

dennisreimann

{-

   This file is a reaction to the article "A small dive into, and rejection of, Elm":
   https://hackernoon.com/a-small-dive-into-and-rejection-of-elm-8217fd5da235#.9w3ml4r6b

   I think constructive criticism is very welcome in the Elm community. Pointing out
   possibilities for documentation improvements, mentioning missing features or ways
   in which the language could evolve etc. are imho a vital part of a good community.

   However, the article above is neither well informed nor constructive. IMHO ranting

jcushman

-- Enable pl/v8:
CREATE EXTENSION plv8;

-- Create json history table:
CREATE TABLE json_history (id BIGSERIAL PRIMARY KEY, tstamp timestamp DEFAULT now(), table_name text, column_name text, target_id bigint, transform json);

-- Create test table:
CREATE TABLE test_json (id BIGSERIAL PRIMARY KEY, data JSON);

-- Enable history tracking on test_json.data:

rosszurowski

[
  { "name": "Afghanistan", "lat": 33, "long": 66 },
  { "name": "Albania", "lat": 41, "long": 20 },
  { "name": "Algeria", "lat": 28, "long": 3 },
  { "name": "Andorra", "lat": 42.5, "long": 1.5 },
  { "name": "Angola", "lat": -12.5, "long": 18.5 },
  { "name": "Antigua and Barbuda", "lat": 17.05, "long": -61.8 },
  { "name": "Argentina", "lat": -34, "long": -64 },
  { "name": "Armenia", "lat": 40, "long": 45 },
  { "name": "Australia", "lat": -25, "long": 135 },

tomhicks

/*
Copy this into the console of any web page that is interactive and doesn't
do hard reloads. You will hear your DOM changes as different pitches of
audio.

I have found this interesting for debugging, but also fun to hear web pages
render like UIs do in movies.
*/

const audioCtx = new (window.AudioContext || window.webkitAudioContext)()

llelf

   what               k4/k7         k9              example    result                
  ---------------------------------------------------------------------------------
   each-left         a f\:b     a f\:b            (!3)*\:!2    (0 0;0 1;0 2)         
   each-right        a f/:b     a f/:b            (!3)*/:!2    (0 0 0;0 1 2)         
   fold                 f/v        f/v                */6 7    42                    
   fold w/initial     a f/v      a f/v             7*/11 13    1001                  
   scan                 f\v        f\v              -\1 1 1    1 0 -1                
   scan w/initial     a f\v      a f\v             3-\1 1 1    2 1 0