Beau Harrington bohford

How I set up a new Mac

Install Apps

First I install some apps. I try to use the AppStore for everything if I can, buth unfortunately that’s not possible. YMMV.

AppStore

This blog post series has moved here.

You might also be interested in the 2016 version.

This is material to go along with a 2014 Boston Haskell talk.

We are going to look at a series of type signatures in Haskell and explore how parametricity (or lack thereof) lets us constrain what a function is allowed to do.

Let's start with a decidedly non-generic function signature. What are the possible implementations of this function which typecheck?

wrangle :: Int -> Int

Fire up ghci. Make the text real big. Always show the types for everything as you go!

Takes ~1 hour generally.

Note: if you object to "uncertainty" (evocative of data/value flow possibilities), consider wording like "simultaneously possible values". It's a reference to how the compiler won't know whether Maybe a is a Just a or a Nothing statically. Don't blather at me about dependent types; I know.

Alternate verbiage for uncertainty: product - simultaneous altogetherness, sum - simultaneous singlehood. Also consider what the category theoretic diagrams look like. Can be instructive.

Suggestions taken under advisement.

	{-# LANGUAGE RecordWildCards, Arrows #-}

	import Numeric
	import Data.Char

	import Control.Monad
	import Data.Monoid ((<>))
	import Data.List (nub, sort, reverse)

	data RepeatBounds = RB

	var child_process = require('child_process');

	exports.handler = function(event, context) {
	var proc = spawn('./test', [ JSON.stringify(event) ], { stdio: 'inherit' });

	proc.on('close', function(code){
	if(code !== 0) {
	return context.done(new Error("Process exited with non-zero status code"));
	}

	{-# LANGUAGE OverloadedStrings #-}

	module Main where

	import Control.Lens -- lens
	import Control.Monad.IO.Class -- transformers
	import Control.Monad.Trans.AWS -- amazonka
	import Network.AWS.EC2 -- amazonka-ec2

	main :: IO ()

	(require '[clojure.test :as test])

	; Rewrite clojure.test to generate data structures instead of writing to
	; stdout
	(def ^:dynamic results
	"Bound dynamically to an atom wrapping a vector of test report maps")

	(defn add-name
	"Given a testing report map, assoc's on a :name derived from the current
	`clojure.test/testing` context."

	#!/bin/bash

	# Check out the blog post at:
	#
	# http://www.philipotoole.com/influxdb-and-grafana-howto
	#
	# for full details on how to use this script.

	AWS_EC2_HOSTNAME_URL=http://169.254.169.254/latest/meta-data/public-hostname
	INFLUXDB_DATABASE=test1

	import Control.Monad.State

	type App = StateT String IO

	main :: IO ()
	main = do
	x <- runStateT code ""
	print x -- ("stateResult","stateValue")
	return ()