Shard Detail

uncons v0.1.0

A toy implementation of head|tail destructuring for the Immutable library
crystal functional-programming functional persistent immutable

Install & Use

Add the following code to your project's shard.yml under:

dependencies to use in production
- OR -
development_dependencies to use in development

  github: Fusion/



Somewhat naive, thread-safe head|tail destructuring for Luca Ongaro's Immutable library.

It's a toy implementation that adds path copying to the 'left side' of the hybrid trie implemented by Luca. It fits my need for a proper 'uncons' mechanism but I would not recommend using it against really big data structures.

Speaking of functional programming, a quick re-read shows that it is unlikely that LLVM will be able to perform tail recursion optimization on the library itself.

If you are interested in persistent data structures, I would recommend researching balanced binary trees and reading any publication by Chris Okasaki.


Add this to your application's shard.yml:

    github: fusion/


require "uncons"

You get, for Vector only: uncons head head? tail tail?


  1. Fork it ( )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request


  • fusion Chris F Ravenscroft - creator, maintainer