kbridge

Understanding the Phases Applicative

While I was researching how to do level-order traversals of a binary tree in Haskell, I came across a library called tree-traversals which introduced a fancy Applicative instance called Phases. It took me a lot of effort to understand how it works. Although I still have some unresolved issues, I want to share my journey.

Note: I was planning to post this article on Reddit. But I gave up because it was too long so here might be a better place.

See the discussion.

Note: This article is written in a beginner-friendly way. Experts may find it tedious.

eliocamp

#' Smooths a 2D field
#' 
#' @param x,y Vector of x and y coordinates
#' @param value Vector of values
#' @param kx,ky Proportion of components to keep in the x and 
#' y direction respectively. Lower values increased the smoothness.
#' 
#' @examples 
#' library(ggplot2)
#' # Creates a noisy version of the volcano dataset and applies the smooth

DanielJWood

https://naturalearth.s3.amazonaws.com/10m_cultural/ https://naturalearth.s3.amazonaws.com/10m_cultural/10m_cultural.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_antarctic_claim_limit_lines.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_antarctic_claims.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_boundary_lines_disputed_areas.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_boundary_lines_land.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_boundary_lines_map_units.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_boundary_lines_maritime_indicator.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_countries.zip https://naturalearth.s3.amazonaws.com/10m_cultural/ne_10m_admin_0_countries_lakes.zip

dino-

#! /usr/bin/env stack
-- stack --resolver lts-18.8 script

{-# LANGUAGE OverloadedStrings #-}

{-
This is a handy illustration of converting between five of the commonly-used
string types in Haskell (String, ByteString, lazy ByteString, Text and lazy
Text).

lislis

# [...]

addons:
  chrome: stable

dsample

ASCI art characters for creating diagrams

Characters:

Single line

• ASCII code 191 = ┐ ( Box drawing character single line upper right corner )
• ASCII code 192 = └ ( Box drawing character single line lower left corner )
• ASCII code 193 = ┴ ( Box drawing character single line horizontal and up )
• ASCII code 194 = ┬ ( Box drawing character single line horizontal down )

benmarwick

# Adapted from https://stackoverflow.com/a/7267364/1036500 by Andrie de Vries

# This is it: theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust = 0.5))

library(ggplot2)

td <- expand.grid(
  hjust=c(0, 0.5, 1),
  vjust=c(0, 0.5, 1),
  angle=c(0, 45, 90),

cscalfani

Monoids in Haskell, an Introduction

Why should programmers care about Monoids? Because Monoids are a common pattern that shows up over and over in programming. And when patterns show up, we can abstract them and leverage work we've done in the past. This allows us to quickly develop solutions on top of proven, stable code.

Add Commutative Property to a Monoid (Commutative Monoid) and you have something that can be executed in parallel. With the end of Moore's Law, parallelism is our only hope to increasing processing speeds.

What follows is what I've learned after studying Monoids. It is hardly complete, but hopefully will prove to be helpful as an introduction for others.

Monoid Lineage

robertpainsi

Commit Message Guidelines

Short (72 chars or less) summary

More detailed explanatory text. Wrap it to 72 characters. The blank
line separating the summary from the body is critical (unless you omit
the body entirely).

Write your commit message in the imperative: "Fix bug" and not "Fixed
bug" or "Fixes bug." This convention matches up with commit messages

vhodges

/**
 * A simple theme for reveal.js presentations, derived from serif.css 
 * It's in the spirit of the Metropolis theme for beamer https://github.com/matze/mtheme
 *
 * This theme is Copyright (C) 2016 Vince Hodges, http://sourdoughlabs.com - it is MIT licensed.
 */

@import url('https://fonts.googleapis.com/css?family=Fira+Sans');

.reveal a {