feat(tvix/eval): Implement builtins.elem r/5080

Change-Id: Id99c1d33f87ad9866990d3483d3531e9e48f861f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6916
Autosubmit: grfn <grfn@gws.fyi>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

1 files changed, 8 insertions, 0 deletions

diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index 5819796236..8929d91cc9 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -174,6 +174,14 @@ fn pure_builtins() -> Vec<Builtin> {
             &[false, false],
             |args: Vec<Value>, vm: &mut VM| arithmetic_op!(&*args[0].force(vm)?, &*args[1].force(vm)?, /),
         ),
+        Builtin::new("elem", &[true, true], |args: Vec<Value>, vm: &mut VM| {
+            for val in args[1].to_list()? {
+                if val.nix_eq(&args[0], vm)? {
+                    return Ok(true.into());
+                }
+            }
+            Ok(false.into())
+        }),
         Builtin::new("elemAt", &[true, true], |args: Vec<Value>, _: &mut VM| {
             let xs = args[0].to_list()?;
             let i = args[1].as_int()?;