Compiles again after command subsystem

terrified to start testing

orchid-extension/src/conv.rs

@@ -2,19 +2,20 @@ use std::future::Future;
 use std::pin::Pin;
 
 use dyn_clone::DynClone;
+use futures::future::FusedFuture;
 use never::Never;
 use orchid_base::{Format, OrcErrv, OrcRes, Pos, fmt, is, mk_errv};
 use trait_set::trait_set;
 
-use crate::atom::{AtomicFeatures, ForeignAtom, TAtom};
-use crate::expr::{Expr, ExprKind};
 use crate::gen_expr::{GExpr, bot};
+use crate::{AtomicFeatures, Expr, ExprKind, ForeignAtom, TAtom};
 
-/// Attempt to cast a generic Orchid expression reference to a concrete value.
-/// Note that this cannot evaluate the expression, and if it is not already
-/// evaluated, it will simply fail. Use [crate::ExecHandle::exec] inside
-/// [crate::exec] to wait for an expression to be evaluated
+/// Values that may be converted from certain specific Orchid expressions
 pub trait TryFromExpr: Sized {
+	/// Attempt to cast a generic Orchid expression reference to a concrete value.
+	/// Note that this cannot evaluate the expression, and if it is not already
+	/// evaluated, it will simply fail. Use [crate::ExecHandle::exec] inside
+	/// [crate::exec] to wait for an expression to be evaluated
 	fn try_from_expr(expr: Expr) -> impl Future<Output = OrcRes<Self>>;
 }
 
@@ -58,6 +59,9 @@ impl<A: AtomicFeatures> TryFromExpr for TAtom<A> {
 
 /// Values that are convertible to an Orchid expression. This could mean that
 /// the value owns an [Expr] or it may involve more complex operations
+///
+/// [ToExpr] is also implemented for [orchid_base::Sym] where it converts to a
+/// reference to the constant by that name
 pub trait ToExpr {
 	/// Inline the value in an expression returned from a function or included in
 	/// the const tree returned by [crate::System::env]
@@ -69,6 +73,8 @@ pub trait ToExpr {
 	}
 }
 
+/// A wrapper for a future that implements [ToExpr]
+#[derive(Clone, Copy, Debug, Default, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub struct ToExprFuture<F>(pub F);
 
 impl<F: Future<Output: ToExpr>> ToExpr for ToExprFuture<F> {
@@ -78,6 +84,9 @@ impl<F: Future<Output: ToExpr>> ToExpr for ToExprFuture<F> {
 		self.0.await.to_expr().await
 	}
 }
+impl<F: FusedFuture> FusedFuture for ToExprFuture<F> {
+	fn is_terminated(&self) -> bool { self.0.is_terminated() }
+}
 impl<F: Future> Future for ToExprFuture<F> {
 	type Output = F::Output;
 	fn poll(self: Pin<&mut Self>, cx: &mut std::task::Context<'_>) -> std::task::Poll<Self::Output> {