refactor(tvix/eval): use im::Vector for NixList representation r/5534

This is a persistent, structurally sharing data structure which is
more efficient in some of our use-cases. I have verified the
efficiency improvement using `hyperfine` repeatedly over expressions
on nixpkgs.

Lists are not the most performance-critical structure in Nix (that
would be attribute sets), but we can already see a small (~5-10%)
improvement.

Note that there are a handful of cases where we still go via `Vec`
that need to be fixed, most notable for `builtins.sort` which can not
currently be implemented directly using `im::Vector` because of a
restrictive type bound.

Change-Id: I237cc50cbd7629a046e5a5e4601fbb40355e551d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7670
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

2 files changed, 55 insertions, 2 deletions

diff --git a/corp/tvixbolt/Cargo.lock b/corp/tvixbolt/Cargo.lock
index 5ddeb6beecd2..41bd8a315f4a 100644
--- a/corp/tvixbolt/Cargo.lock
+++ b/corp/tvixbolt/Cargo.lock
@@ -35,6 +35,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
+name = "bitmaps"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "031043d04099746d8db04daf1fa424b2bc8bd69d92b25962dcde24da39ab64a2"
+dependencies = [
+ "typenum",
+]
+
+[[package]]
 name = "boolinator"
 version = "2.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -274,6 +283,20 @@ dependencies = [
 ]
 
 [[package]]
+name = "im"
+version = "15.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0acd33ff0285af998aaf9b57342af478078f53492322fafc47450e09397e0e9"
+dependencies = [
+ "bitmaps",
+ "rand_core",
+ "rand_xoshiro",
+ "sized-chunks",
+ "typenum",
+ "version_check",
+]
+
+[[package]]
 name = "indexmap"
 version = "1.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -395,6 +418,21 @@ dependencies = [
 ]
 
 [[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+
+[[package]]
+name = "rand_xoshiro"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f97cdb2a36ed4183de61b2f824cc45c9f1037f28afe0a322e9fff4c108b5aaa"
+dependencies = [
+ "rand_core",
+]
+
+[[package]]
 name = "redox_syscall"
 version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -533,6 +571,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "sized-chunks"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "16d69225bde7a69b235da73377861095455d298f2b970996eec25ddbb42b3d1e"
+dependencies = [
+ "bitmaps",
+ "typenum",
+]
+
+[[package]]
 name = "slab"
 version = "0.4.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -612,6 +660,7 @@ dependencies = [
  "codemap",
  "codemap-diagnostic",
  "dirs",
+ "im",
  "path-clean",
  "regex",
  "rnix",
@@ -648,6 +697,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "typenum"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "497961ef93d974e23eb6f433eb5fe1b7930b659f06d12dec6fc44a8f554c0bba"
+
+[[package]]
 name = "unicode-ident"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/corp/tvixbolt/Cargo.toml b/corp/tvixbolt/Cargo.toml
index 75006bec188e..80a513aef00e 100644
--- a/corp/tvixbolt/Cargo.toml
+++ b/corp/tvixbolt/Cargo.toml
@@ -3,8 +3,6 @@ name = "tvixbolt"
 version = "0.1.0"
 edition = "2021"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [dependencies]
 yew = "0.19.3"
 yew-router = "0.16"