edmundsmith

Method for Emulating Higher-Kinded Types in Rust

Intro

I've been fiddling about with an idea lately, looking at how higher-kinded types can be represented in such a way that we can reason with them in Rust here and now, without having to wait a couple years for what would be a significant change to the language and compiler.

There have been multiple discussions on introducing higher-ranked polymorphism into Rust, using Haskell-style Higher-Kinded Types (HKTs) or Scala-looking Generalised Associated Types (GATs). The benefit of higher-ranked polymorphism is to allow higher-level, richer abstractions and pattern expression than just the rank-1 polymorphism we have today.

As an example, currently we can express this type:

cortesben

Mercurial Commands

Commands	Description
hg pull	get latest changes like git pull use flags like -u IDK why yet
hg add	only for new files
hg commit	add changes to commit with -m for message just like git
hg addremove	adds new files and removes file not in your file system
hg incoming	see changes commited by others
hg outgoing	see local commits

schacon

the plumbing commands

• rev-parse [something]

  • show the SHA of any weird git phrase

• hash-object -w [file]

  • take any file or stdin and return a blob sha

• ls-tree (-r) [sha]

• show the entries of a git tree in the db