nushell/crates/nu-cmd-lang
Ian Manske 9996e4a1f8
Shrink the size of Expr (#12610)
# Description
Continuing from #12568, this PR further reduces the size of `Expr` from
64 to 40 bytes. It also reduces `Expression` from 128 to 96 bytes and
`Type` from 32 to 24 bytes.

This was accomplished by:
- for `Expr` with multiple fields (e.g., `Expr::Thing(A, B, C)`),
merging the fields into new AST struct types and then boxing this struct
(e.g. `Expr::Thing(Box<ABC>)`).
- replacing `Vec<T>` with `Box<[T]>` in multiple places. `Expr`s and
`Expression`s should rarely be mutated, if at all, so this optimization
makes sense.

By reducing the size of these types, I didn't notice a large performance
improvement (at least compared to #12568). But this PR does reduce the
memory usage of nushell. My config is somewhat light so I only noticed a
difference of 1.4MiB (38.9MiB vs 37.5MiB).

---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>
2024-04-24 15:46:35 +00:00
..
src Shrink the size of Expr (#12610) 2024-04-24 15:46:35 +00:00
build.rs Cratification: Break out nu_cmd_lang into a separate crate (#8181) 2023-02-24 09:54:42 -06:00
Cargo.toml Update crate feature flags (#12566) 2024-04-18 16:33:41 +02:00
LICENSE Fix rest of license year ranges (#8727) 2023-04-04 09:03:29 +12:00
README.md nu-cmd-lang readme (#9446) 2023-06-15 08:45:23 -07:00

nu-cmd-lang

the base language and command crate of nu

The commands in this crate are the core commands of the nu language. It is also the base crate upon which all other command crates sit on top of including:

  • nu-command
  • nu-cli
  • nu-cmd-dataframe
  • nu-cmd-extra

As time goes on and the nu language develops further in parallel with nushell we will be adding other command crates to the system.

What does it mean to be a base crate ?

A base crate is one with minimal dependencies in our system so that other developers can come along and use this crate without having a lot of baggage in terms of other crates which will bloat their underlying application.

Background on nu-cmd-lang

This crate was designed to be a small, concise set of tools or commands that serve as the foundation layer of both nu and nushell. These are the core commands needed to have a nice working version of the nu language without all of the support that the other commands provide inside nushell. Prior to the launch of this crate all of our commands were housed in the crate nu-command. Moving forward we would like to slowly break out the commands in nu-command into different crates; the naming and how this will work and where all the commands will be located is a "work in progress" especially now that the standard library is starting to become more popular as a location for commands. As time goes on some of our commands written in rust will be migrated to nu and when this happens they will be moved into the standard library.