From 9407af5684ca5602df51c4edddc428db7fc98417 Mon Sep 17 00:00:00 2001
From: Vincent Ambo <mail@tazj.in>
Date: Thu, 11 Aug 2022 11:55:59 +0300
Subject: refactor(tvix/eval): encapsulate list construction in value::list

Ensuring that the implementation is not leaking out of the module lets
us keep things open for optimisations (e.g. empty list or pairs
through tuples).

Change-Id: I18fd9b7740f28c55736471e16c6b4095a05dd6d0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6145
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
---
 tvix/eval/src/value/list.rs | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

(limited to 'tvix/eval/src/value')

diff --git a/tvix/eval/src/value/list.rs b/tvix/eval/src/value/list.rs
index f9d85229410a..546d2c88a55a 100644
--- a/tvix/eval/src/value/list.rs
+++ b/tvix/eval/src/value/list.rs
@@ -4,7 +4,7 @@ use std::fmt::Display;
 use super::Value;
 
 #[derive(Clone, Debug, PartialEq)]
-pub struct NixList(pub Vec<Value>);
+pub struct NixList(Vec<Value>);
 
 impl Display for NixList {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
@@ -26,4 +26,15 @@ impl NixList {
         lhs.0.append(&mut rhs.0);
         lhs
     }
+
+    pub fn construct(count: usize, stack_slice: Vec<Value>) -> Self {
+        debug_assert!(
+            count == stack_slice.len(),
+            "NixList::construct called with count == {}, but slice.len() == {}",
+            count,
+            stack_slice.len(),
+        );
+
+        NixList(stack_slice)
+    }
 }
-- 
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