expr VS npeg

I had to write an expression parser recently and found the number of names for essentially the same algorithm very confusing. There's Pratt parsing, precedence climbing, and shunting yard. But really they're all the same algorithm.

Pratt parsing and precedence climbing are the same except one merges left/right associativity precedence into a single precedence table (which makes way more sense). Shunting yard is the same as the others except it's iterative instead of recursive, and it seems like common implementations omit some syntax checking (but there's no reason you have to omit it).

Here's what I ended up with:

https://github.com/Timmmm/expr

I had to write that because somewhat surprisingly I couldn't find an expression parser library that supports 64-bit integers and bools. Almost all of them only do floats. Also I needed it in C++ - that library was a prototype that I later translated into C++ (easier to write in Rust and then translate).

Ha, nice to see this on HN: this article was pretty helpful to me to understand the concept a few years back when extending my PEG parsing library [1] with a Pratt parser; this mitigates the problem of PEG parsers not allowing left recursion and allows for a much more concise notation of grammars with operator precedence. Thank you Bob:

1. https://github.com/zevv/npeg

Ones that have not been mentioned so far:

nlvm is an unofficial LLVM backend: https://github.com/arnetheduck/nlvm

npeg lets you write PEGs inline in almost normal PEG notation: https://github.com/zevv/npeg

futhark provides for much more automatic C interop: https://github.com/PMunch/futhark

nimpy allows calling Python code from Nim and vice versa: https://github.com/yglukhov/nimpy

questionable provides a lot of syntax sugar surrounding Option/Result types: https://github.com/codex-storage/questionable

ratel is a framework for embedded programming: https://github.com/PMunch/ratel

cps allows arbitrary procedure rewriting to continuation passing style: https://github.com/nim-works/cps

chronos is an alternative async/await backend: https://github.com/status-im/nim-chronos

zero-functional fixes some inefficiencies when chaining list operations: https://github.com/zero-functional/zero-functional

owlkettle is a declarative macro-oriented library for GTK: https://github.com/can-lehmann/owlkettle

A longer list can be found at https://github.com/ringabout/awesome-nim.