• bit of history

  Macros can be used to make tasks less repetitive by representing a complicated sequence of keystrokes, mouse movements, commands, or other types of input. In computer programming, macros are a tool that allows a developer to re-use code.

• best explianation i have found so far

  Fundamentally, macros are a way of writing code that writes other code, which is known as metaprogramming. rust docs

• macro is going to happen at compile time. where a function is going to happen at run time.

• code that writes code. ? This is less readable, understandable, and maintainable then general functions.

Two types of macros

1. Declaritive w/ general metaprogramming

   • Matching on patterns and replacing code

2. Prodecural more like functions

   • given input -> producing output (pure)

3. Problem babel macros sets to solve solution

   • They can lead to confusion because when looking at code in a project, you might not know that there’s a plugin transforming that code.
   • They have to be globally configured or configured out-of-band (in a .babelrc or webpack config).
   • They can conflict in very confusing ways due to the fact that all babel plugins run simultaneously (on a single walk of Babel’s AST).

4. Solution

   • transformations with:
   • zero config
   • importability

Explicit is often a better pattern than implicit because it requires others to understand how things are globally configured. This is in this spirit are babel-plugin-macros designed. However, some things do need to be implicit, and those kinds of babel plugins can’t be turned into macros.

• the idea of syntax macro it’s well suited for babel-plugin-macros

What would it take to enable JS Macros to open stage proposals to actual implementations?

TC-39 Proposals

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