Darius Foo dariusf

Using Apron on macOS

Install PPL.

brew install ppl

For some reason, installing from opam doesn't pick up the presence of PPL. We run ./configure manually to fix that.

Pandas

Mental model

Pandas is oriented around performing SIMD operations on arrays, and its API directly reflects this. Some operations may be less intuitive than they are in the SQL or stream processing worlds. Operations like apply and iter* which involve user-defined Python are generally slow.

Basics

$$\mathit{Total\ Correctness} = \mathit{Partial\ Correctness} + \mathit{Termination}$$ Program Verification

$$\mathit{Emacs} + \mathit{Go} = \mathit{Parametric\ Polymorphism}$$ Fulfilling a Pikedream: the ups of downs of porting 50k lines of C++ to Go.

Updated Feb 2022.

ShiViz visualizes space-time diagrams, a succinct way to represent distributed system executions.

The examples on the site are all rather large, so here's a tiny Hello World example which illustrates the input format and basic ideas.

client1 "message 1 sent" {"client1":1}
client2 "message 2 sent" {"client2":1}
server "message 2 received" {"server":1, "client2":1}

Updated Dec 2021.

Zoom doesn't have chat notifications. This is a problem when invigilating online exams.

If you're using macOS, notifications can be hacked on by using a bunch of scripts to tell when something on the screen changes.

Rectangles

The first piece is how to capture a small region of the screen.

VirtualBox for Docker users

Sometimes you need VirtualBox instead of Docker - when more isolation is required, or because a desktop environment is too hard to configure.

(Updated Sep 2021)

	(* Based on

	https://okmij.org/ftp/continuations/implementations.html
	https://okmij.org/ftp/Haskell/ShiftResetGenuine.hs
	https://www.cs.tsukuba.ac.jp/~kam/paper/aplas07.pdf *)

	(* Parameterised monads *)
	module type GM = sig
	type ('i, 'o, 'a) t

	-- h ttps://stackoverflow.com/questions/72833519/how-to-extract-delimited-continuation-reset-shift-for-future-use-in-haskell/72836141#72836141
	{-# LANGUAGE RebindableSyntax #-}

	import Data.String
	import Prelude hiding ((>>=), return)

	newtype Cont i o a = Cont { runCont :: (a -> i) -> o }

	return :: a -> Cont r r a
	return x = Cont ($ x)

	// Keybindings for compound rubrics
	document.onkeypress = function(e) {
	if (e.key === 'n') {
	setTimeout(() => {
	// both events have to be sent
	document.dispatchEvent(new KeyboardEvent('keydown', {'key': 'j'}));
	document.dispatchEvent(new KeyboardEvent('keyup', {'key': 'j'}));
	setTimeout(() => {
	document.dispatchEvent(new KeyboardEvent('keydown', {'key': 'k'}));
	document.dispatchEvent(new KeyboardEvent('keyup', {'key': 'k'}));

	type 'a tree =
	\| Section of {
	item : 'a;
	children : 'a tree list;
	}

	let item a = Section { item = a; children = [] }

	type 'a path =
	\| Top