From 5b9c4d29f643f20ea8f37e94e95e05354e0e5e93 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Wed, 30 Jun 2021 15:05:57 +0200
Subject: [PATCH] impl Domain for Arc<D: Domain>

---
 implementations/rust/preserves/src/value/repr.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/implementations/rust/preserves/src/value/repr.rs b/implementations/rust/preserves/src/value/repr.rs
index b89abd6..ecb5a77 100644
--- a/implementations/rust/preserves/src/value/repr.rs
+++ b/implementations/rust/preserves/src/value/repr.rs
@@ -11,6 +11,7 @@ use std::marker::PhantomData;
 use std::ops::Index;
 use std::ops::IndexMut;
 use std::string::String;
+use std::sync::Arc;
 use std::vec::Vec;
 
 pub use std::collections::BTreeSet as Set;
@@ -25,6 +26,16 @@ pub trait Domain: Sized + Debug + Clone + Eq + Hash + Ord {
     fn as_preserves(&self) -> IOValue;
 }
 
+impl<D: Domain> Domain for Arc<D> {
+    fn from_preserves(v: IOValue) -> IOResult<Self> {
+        Ok(Arc::new(D::from_preserves(v)?))
+    }
+
+    fn as_preserves(&self) -> IOValue {
+        D::as_preserves(self)
+    }
+}
+
 pub trait NestedValue<D: Domain>: Sized + Debug + Clone + Eq + Hash + Ord {
     fn wrap(anns: Annotations<Self, D>, v: Value<Self, D>) -> Self;
 
@@ -1046,8 +1057,6 @@ impl<'de, Dom: Domain> serde::Deserialize<'de> for RcValue<Dom> {
 
 //---------------------------------------------------------------------------
 
-use std::sync::Arc;
-
 #[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct ArcValue<D: Domain>(Arc<AnnotatedValue<ArcValue<D>, D>>);