AyeGill

#Retail typing In which I describe an idea I had for a type system. Or something.

##Intro: Duck typing Duck typing (as in, "if it quacks like a duck...") typically refers to a specific sort of dynamic typing common in dynamically typed, object oriented languages. As an example, consider ruby:

def foo(arg)
  arg.bar.baz
end

So, haskell is a "Pure Functional" language, which basically means that functions behave(almost) like mathematical functions, rather than how they behave in other languages. So in most other languages a function can do whatever before it returns, print some text, wipe the root partition, launch nukes against China, whatever. In haskell, that's (almost) not allowed: a function takes an argument, returns an argument, and that's it.

So how do you accomplish anything? Software has to actually do stuff, so how do you interact with anything? To explain that, we need a brief interlude to explain types in haskell. First there are simple types like int, string, so on. Just like a type in C. Then you have parametric types, like List. So you can have a List int, or a List string, and that's a linked list of integers or strings. Lastly, we need to explain parametric types. For example, you might have a function that takes the length of a list. The thing about that function is that it actually doesn't care abou

How to make graphs for tikz easily

Necessary utilities: graphviz, dot2tex, xsel. Install these:

$ sudo apt install graphviz
$ sudo apt install xsel
$ pip3 install dot2tex

	(defun view-latex ()
	(interactive)
	(if (buffer-modified-p) (save-buffer))
	(shell-command (concat "pdflatex " buffer-file-name " >> /dev/null"))
	(shell-command (concat "evince " (substring buffer-file-name 0
	(- (length buffer-file-name) 4)) ".pdf >> /dev/null")))
	;Obviously, replace "pdflatex" and "evince" with your own latex and pdf viewer systems, respectively.
	;

	\documentclass{article}
	\usepackage{mathtools}
	\begin{document}
	\[ \pi * 10^7 \approx 3652460*60 = 1 yr\footnotemark
	\]

	\footnotetext{The actual astronomical year is, of course, slightly longer than this, depending on which standard you use. But the deviation is about .25 day, which is well within the margin of error anyways. For more information, you may consult the wikipedia article ``Year''}

	More precisely:

	{-# LANGUAGE TypeOperators
	, Arrows
	, FlexibleInstances
	, DeriveDataTypeable
	, StandaloneDeriving
	, GeneralizedNewtypeDeriving#-}

	import Prelude hiding ((.))
	import Data.Dynamic
	import qualified Data.Map as M

	{-# LANGUAGE DataKinds, GADTs, StandaloneDeriving, FlexibleInstances, FlexibleContexts #-}

	import Data.Foldable hiding (foldl)
	import Data.Traversable
	import Data.Monoid
	import Control.Applicative

	-- vector stuff --
	data Nat = Z \| S Nat

	{{
	--Arbitrary haskell code in double curly brackets
	--Top-level definitions are available throughout text
	emph s = "" ++ s ++ ""
	}}

	This will be rendered raw.
	{{
	-- String-typed expressions will be printed into the final text wherever they appear
	emph "This will be emphasized"

	#!/usr/bin/python3
	import arxiv
	import sys
	import PyPDF4
	import re

	## Usage: arxiref.py 1711.07059
	## or: arxiref.py paper.pdf
	## If given something that looks like an arXiv id, searches for something with that name
	## If given a filename, treats it as a pdf, looks for an arXiv id on page 1, then proceeds as in first case

	#!/usr/bin/env python

	import urllib as ul
	import re
	import sys
	import os.path
	#Pandoc turns this: [foo]([[My Foo Page]])
	#Into this: [[file:%5B%5BMy%20Foo%20Page%5B%5B][foo]]
	#We want this: [[file:My Foo Page.org][foo]]