Nulls and options (a note from Hacker News)

A quick note from Hacker News about why we want optional types but why ’null’ is unintuitive.

The uncountability of the reals (a note from Hacker News)

A quick note from Hacker News about a beautiful proof of the uncountability of the reals.

In favour of recursive functions, not imperative constructs, to make loops

How to write loops immutably and safely.

Static config (a note from Hacker News)

A quick note from Hacker News about my preference for static config rather than dynamic.

Defunctionalisation

An underappreciated tool for writing good software.

MIT Mystery Hunt photos

Photos from the Mystery Hunt.

MIT Mystery Hunt 2020 answers

A couple of solution documents I made during the progress of the 2020 MIT Mystery Hunt.

Teaching how to cook (a note from Hacker News)

A quick note from Hacker News about my thoughts on teaching cookery.

The stages of mathematics teaching (a note from Hacker News)

A quick note from Hacker News about the various stages of learning and teaching in mathematics.

MIT Mystery Hunt 2019 answers

A couple of solution documents I made during the progress of the 2019 MIT Mystery Hunt.

Chatting with Don Syme about the F# compiler

Notes from a chat with the creator of F#, about how to contribute to the compiler.

Dependent types overview

A quick overview of dependent types.

JSON comments (a note from Hacker News)

A quick note from Hacker News about why the comment-handling situation in JSON is bad.

What is lost when we move between number systems?

Answering the question, “What is lost when we move from the reals to the complex numbers?”.

Infinitesimals as an idea that took a long time

Answering the question, “Which mathematical ideas took a long time to define rigorously?”.

Abuse of notation in function application

Answering the question, “Are these examples of abuses of notation?”.

The relationship between the IMO and research mathematics

Answering the question, “does the International Maths Olympiad help research mathematics?”.

Proof of Cauchy-Schwarz

This is just a link to a beautiful proof of the Cauchy-Schwarz inequality. There are a number of elegant proofs, but this is by far my favourite, because (as pointed out in the paper) it “builds itself”.

What does Mathematica mean by ComplexInfinity?

Answering the question, “Why does WolframAlpha say that a quantity is ComplexInfinity?”.

How far back does mathematical understanding go?

Answering the question, “how far back in time would maths be understandable to a modern mathematician?”.