21 Nov 2024
Should a programming language be powerful and let a programmer do a lot, or should it be safe and protect the programmer from bad mistakes? Contrary to what the title insinuates, these are not diametrically opposed attributes. Nevertheless, this is the mindset that underlies notions such as, “macros, manual memory management, etc. are power tools—they’re not supposed to be safe.” If safety and power are not necessarily opposed, why does this notion persist?
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6 May 2024
This is the story of how I solved a problem (ugly, cumbersome boilerplate code) that I ran into while writing a program in a functional language (Elixir). Functional programming languages often pride themselves on expressiveness and elegance; but occasionally they are not amenable to the most obvious solutions to the problems we wish to solve. In this case, the simplest solution to my problem would have been to have a global mutable variable. But no one likes those.
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13 Nov 2023
Macros are tricky beasts. Most languages—if they have macros at all—usually include a huge “here there be dragons” warning to warn curious would-be macro programmers of the dangers that lurk ahead.
What is it about macros that makes them so dangerous and unwieldy? That’s difficult to answer in general: there are many different macro systems with varying degrees of ease-of-use. Moreover, making macros easy to use safely is an open area of research—most languages that have macros don’t have features necessary to implement macros safely. Hence, most people steer clear of macros.
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14 Aug 2023
There’s a neat paper Type Systems as Macros by Chang, Knauth, and Greenman [1] that describes how to implement a typed language using an untyped host language and macro expansion. The paper is neat, but I found the code hard to follow—the paper uses a compact notation that’s convenient for print, but not so much for reproducing on one’s own. This post is my attempt to implement and explain in more accessible terms what’s presented in the paper.
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19 May 2023
There are a bunch of different ways of writing a macro in Racket. There are also some tricky things around phases to keep in mind. This is to help me keep them all straight.
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