refactor(tvix/eval): remove use of imbl::Vector

This vector type has served us well for now, but it contains internal refcounts
which are incompatible with upcoming changes related to garbage collection.

The performance impact of this change within all benchmarks I ran was within the
margin of error:

[nix-shell:/tmp/perf]$ hyperfine "./before -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings"
Benchmark 1: ./u64 -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings
  Time (mean ± σ):      7.528 s ±  0.272 s    [User: 6.578 s, System: 0.631 s]
  Range (min … max):    7.160 s …  8.012 s    10 runs

nix-shell:/tmp/perf]$ hyperfine "./std-vec -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings"
Benchmark 1: ./std-vec -E '(import <nixpkgs> {}).firefox.outPath' --log-level ERROR --no-warnings
  Time (mean ± σ):      7.515 s ±  0.178 s    [User: 6.508 s, System: 0.652 s]
  Range (min … max):    7.276 s …  7.861 s    10 runs

Change-Id: Ib95f871956e336a1e5771f6293583854b1efb276
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12197
Reviewed-by: aspen <root@gws.fyi>
Tested-by: BuildkiteCI

tvix/eval/src/value/arbitrary.rs

@@ -1,6 +1,7 @@
 //! Support for configurable generation of arbitrary nix values
 
-use imbl::proptest::{ord_map, vector};
+use imbl::proptest::ord_map;
+use proptest::collection::vec;
 use proptest::{prelude::*, strategy::BoxedStrategy};
 use std::ffi::OsString;
 
@@ -53,7 +54,7 @@ impl Arbitrary for NixList {
     type Strategy = BoxedStrategy<Self>;
 
     fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
-        vector(<Value as Arbitrary>::arbitrary_with(args), 0..100)
+        vec(<Value as Arbitrary>::arbitrary_with(args), 0..100)
             .prop_map(NixList::from)
             .boxed()
     }

tvix/eval/src/value/list.rs

@@ -2,8 +2,6 @@
 use std::ops::Index;
 use std::rc::Rc;
 
-use imbl::{vector, Vector};
-
 use serde::Deserialize;
 
 use super::thunk::ThunkSet;
@@ -12,7 +10,7 @@ use super::Value;
 
 #[repr(transparent)]
 #[derive(Clone, Debug, Deserialize)]
-pub struct NixList(Rc<Vector<Value>>);
+pub struct NixList(Rc<Vec<Value>>);
 
 impl TotalDisplay for NixList {
     fn total_fmt(&self, f: &mut std::fmt::Formatter<'_>, set: &mut ThunkSet) -> std::fmt::Result {
@@ -27,8 +25,8 @@ impl TotalDisplay for NixList {
     }
 }
 
-impl From<Vector<Value>> for NixList {
-    fn from(vs: Vector<Value>) -> Self {
+impl From<Vec<Value>> for NixList {
+    fn from(vs: Vec<Value>) -> Self {
         Self(Rc::new(vs))
     }
 }
@@ -54,10 +52,10 @@ impl NixList {
             stack_slice.len(),
         );
 
-        NixList(Rc::new(Vector::from_iter(stack_slice)))
+        NixList(Rc::new(stack_slice))
     }
 
-    pub fn iter(&self) -> vector::Iter<Value> {
+    pub fn iter(&self) -> std::slice::Iter<Value> {
         self.0.iter()
     }
 
@@ -65,19 +63,14 @@ impl NixList {
         Rc::ptr_eq(&self.0, &other.0)
     }
 
-    pub fn into_inner(self) -> Vector<Value> {
+    pub fn into_inner(self) -> Vec<Value> {
         Rc::try_unwrap(self.0).unwrap_or_else(|rc| (*rc).clone())
     }
-
-    #[deprecated(note = "callers should avoid constructing from Vec")]
-    pub fn from_vec(vs: Vec<Value>) -> Self {
-        Self(Rc::new(Vector::from_iter(vs)))
-    }
 }
 
 impl IntoIterator for NixList {
     type Item = Value;
-    type IntoIter = imbl::vector::ConsumingIter<Value>;
+    type IntoIter = std::vec::IntoIter<Value>;
 
     fn into_iter(self) -> Self::IntoIter {
         self.into_inner().into_iter()
@@ -86,7 +79,7 @@ impl IntoIterator for NixList {
 
 impl<'a> IntoIterator for &'a NixList {
     type Item = &'a Value;
-    type IntoIter = imbl::vector::Iter<'a, Value>;
+    type IntoIter = std::slice::Iter<'a, Value>;
 
     fn into_iter(self) -> Self::IntoIter {
         self.0.iter()