patty

> This is a real trade-off. The feature I have here provides strictly less static safety than using sum types. There is a slight performance cost to checking the type tag when accessing case-specific fields. In return, you get simpler, more familiar syntax for working with case-specific fields, including mutable ones. Interesting post! Nim uses variant/case objects as well. Generally they're pretty handy and more flexible than sum types as you can access non-variant fields as regular objects. Though it means you can't use the same field name twice, however on the other hand you can bring common fields out of the case portion. Also, a single object can have multiple case variants which can be handy. There's a PR for adding the stricter sum types and pattern matching as well. https://github.com/nim-lang/RFCs/issues/525 Currently I just use

You might like Patty. It makes case types more ergonomic: https://github.com/andreaferretti/patty

Libraries exist: https://github.com/haxscramper/nimtraits https://github.com/andreaferretti/patty https://github.com/alaviss/union Again we are not new to this problem and already offer alternatives.

...except that macros don't change the syntax of the language! They just offer convenience on top of it, most common example is the `=>` lambda operator from the `sugar` module. I do agree, that the pattern matching macro presented in the article is a bit hard to get used to, but you don't have to, if you don't like pattern matching. And of course there are plenty of alternatives available as well, the simplest one imo is https://github.com/andreaferretti/patty

Are algebraic data types and pattern matching possible in Nim? Googling shows that there are libraries (https://github.com/andreaferretti/patty for example) but basically amounts to deferring their implementation by way of the macro system/metaprogramming.

Yes. ADT are case objects: they are widely used. https://nim-lang.org/docs/tut2.html#object-oriented-programm... There are some macros for easier generation: https://github.com/andreaferretti/patty#constructing-variant... There are pattern matching libs: pattern matching is implemented on top of metaprogramming. General pattern matching: the original https://github.com/andreaferretti/patty https://github.com/alehander42/gara (disclaimer: my lib) patty and gara should eventually combine into a single lib: including probably the current gara matching DSL(inspired by patty) and patty's variant DSL in the same place. AST pattern matching: optimized for macros, nice error reporting https://github.com/krux02/ast-pattern-matching