oseme-techguy

#!/usr/bin/env bash

# To fix the " gpg: WARNING: unsafe permissions on homedir '/home/path/to/user/.gnupg' " error
# Make sure that the .gnupg directory and its contents is accessibile by your user.
chown -R $(whoami) ~/.gnupg/

# Also correct the permissions and access rights on the directory
chmod 600 ~/.gnupg/*
chmod 700 ~/.gnupg

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).

gvolpe

Dependency Injection in Functional Programming

There exist several DI frameworks / libraries in the Scala ecosystem. But the more functional code you write the more you'll realize there's no need to use any of them.

A few of the most claimed benefits are the following:

• Dependency Injection.
• Life cycle management.
• Dependency graph rewriting.

kritzcreek

Generating collections of random numbers in PureScript

A problem that I've seen beginners run into in Haskell or PureScript a couple of times now is how to generate a List of random numbers. It's a common requirement for little games (which make for great first projects) to generate these, and it definitely seems to be a stumbling block.

Why are random numbers hard?

Randomness is considered a side effect in purely functional languages, which means that to generate them you usually need access to Eff/IO, which in turn means we need to deal with Monads. And while generating a single random number is usually pretty easy with do-notation, the typical intuition beginners have built when going from single values to a collection is to use map, but that fails.

Type-Directed-Search to the rescue

DrBoolean

const daggy = require('daggy');
const {foldMap} = require('pointfree-fantasy')
const {concat, toUpper, prop, identity, range, compose} = require('ramda');

// Contravariant functors usually have this shape F(a -> ConcreteType).
// In other words, some type holding a function which is parametric on its input, but not output.
// They don't always have that shape, but it's a good intuition
// Covariant functors are what we're used to, which are parametric in their output
//================================================================

therealklanni

repeat(a) -> [a]

Inspired by Haskell, I wanted to see if I could replicate, using ES6 features, the repeat function:

repeat :: a -> [a]

So as you can see in repeat.js, I have done exactly that. However there are some caveats.

nkpart

fmap . fmap . fmap

Functors and Traversables compose.

You might have seen this statement before. This is how you can take advantage of it.

Composing many fmap calls gives you a function that will drill down into a structure and modify it at a certain depth in that nested structure.

staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---