- Author
- Posted by tie-in, with replies from many commenters
- Published
- 21 June 2026
- Kind
- Hacker News discussion thread with a Show HN launch post
- Original
- news.ycombinator.com/item?id=48620848
- Subject
- Programming languages and types
What it is
Tie-in posted the launch text and answered some replies. The library makes functions return a description of their I/O instead of doing it. The poster says it has run in production since December.
What it says
- The post says a function that returns a description of its I/O is pure.
- The post says tests need no mocking library. They inspect the returned tree instead.
- The post says a recorded trace can be replayed locally with a timeTravel function.
- The post says the library has six primitives, zero dependencies and under 1 KB.
- The post calls Pure Effect a pattern for existing code, unlike the Effect-TS framework.
- Commenter ramon156 says the post and README make many claims without evidence.
- Commenter indiv0 says applying the effects pattern fully runs into many walls.
What evidence it gives
The post shows short code ideas and a feature list. It offers no benchmarks or public case study. The maker links five blog posts, which were not read.
Interests and limits
The maker is promoting their own library, which is at an early version. The linked repository and blog posts were not read. Replies are opinion and were not tested.