https://www.hillelwayne.com/tags/teaching/ Recent content in Teaching on Hillel Wayne Hugo -- gohugo.io en-us Tue, 07 Nov 2023 00:00:00 +0000 https://www.hillelwayne.com/post/lsp/ Tue, 07 Nov 2023 00:00:00 +0000 https://www.hillelwayne.com/post/lsp/ Short version: If X inherits from Y, then X should pass all of Y’s black box tests. I first encountered this idea at SPLASH 2021. The longer explanation A bit of background In A Behavioral Notion of Subtyping Liskov originally defined subtyping in inherited objects as follows: Subtype Requirement: Let P(x) be a property provable about objects x of type T. Then P(y) should be true for objects y of type S where S is a subtype of T. https://www.hillelwayne.com/post/cheatsheets/ Fri, 24 Jul 2020 00:00:00 +0000 https://www.hillelwayne.com/post/cheatsheets/ Now that teach workshops for a living, I spend a lot of time on making better workshops. One improvement I made was creating progressive cheatsheets. I’ll discuss the motivation and implementation below, but this is the high level picture: .gallery { display: flex; text-align: center; } .gallery a { margin: 5px; border-width: 1px; border-style: solid; } Progressions #1 and #2 of the cheatsheet. Click for full size. https://www.hillelwayne.com/post/fairness/ Fri, 03 Jul 2020 00:00:00 +0000 https://www.hillelwayne.com/post/fairness/ I’m in the process of revising some of my workshops. I realized that one particular important aspect of TLA+, fairness, is something that I’ve struggled to explain well. Then again, everybody struggles to explain it well! It’s also a great example of how messy concurrent systems can get, so I figured it would make a good post for the blog. Stuttering Take the following spec of a clock. I used TLA+ but it should mostly be clear from context: https://www.hillelwayne.com/post/teaching-leaky-abstractions/ Tue, 30 Jan 2018 00:00:00 +0000 https://www.hillelwayne.com/post/teaching-leaky-abstractions/ I’m writing a book on TLA+! It’s going to be aimed at the same audience as Learn TLA+, but dive much deeper and go much further. I’ll be showing not just how to use TLA+, but how to think about systems, write good specifications, and fix models. I’m really excited and I’m sure you’ll be, too! I’m also trying to make it much better than Learn TLA+, because People are going to be paying money for this, so I can’t just phone it in I asked my technical reviewer to be “almost-comically brutal” and he’s risen to the challenge. https://www.hillelwayne.com/post/persuasive-examples/ Tue, 29 Aug 2017 00:00:00 +0000 https://www.hillelwayne.com/post/persuasive-examples/ I recently read No excuses, write unit tests, which argues Unit Tests are Good and You Should Write Them. For the most part I strongly agree with their message, which is why I feel kinda bad criticizing the essay. They provide this as “an example of simple testing”: constadd=(...numbers) => { returnnumbers.reduce((acc, val) => { returnacc+val; }, 0); }; it('should add numbers', () => { constexpected=15; constactual=add(1, 2, 3, 4, 5); expect(actual).