Spent the week reading through Saša Jurić’s six-part Understanding macros on The Erlangelist.
I’ve previously managed to wend my way through a macro in one of the Programming Elixir exercises but didn’t really get a handle on it.
Saša’s explanation of quote and unquote was clear and understandable.
Notable Notes and Quotes
- “[Macros keep] the language core minimal, and simplifies further extensions to the language.”
- “somewhat less known is the possibility to generate functions on the fly”
- “Another way of looking at unquote is to treat it as an analogue to string interpolation (
#{}).” - “variables introduced by a macro are its own private affair that won’t interfere with the rest of the code.”
- Use the
var!construct to make a variable visible outside the macro. - “the
usemechanism allows us to inject some piece of code into the caller’s context.” - “
usegenerates a code that generates a code” - “proliferation of macros may make your client code extremly cryptic, since it will rely on custom, non-standard idioms”
- “since they run during compilation, macros make it possible to optimize some code by moving calculations to compile-time”
- “Always remember - macros amount to plain composition of AST fragments during expansion phase”
All notes and comments are my own opinion. Follow me at @rgacote@genserver.social