diff --git a/scopegraphs/src/completeness/implicit.rs b/scopegraphs/src/completeness/implicit.rs
index c6c62c8..2b8b8f3 100644
--- a/scopegraphs/src/completeness/implicit.rs
+++ b/scopegraphs/src/completeness/implicit.rs
@@ -14,7 +14,7 @@ use super::Implicit;
 /// Unlike [`ExplicitClose`](crate::completeness::ExplicitClose), this implementation will implicitly close edges once traversed.
 /// This does not require special attention from the type checker writer.
 ///
-/// Returns [`EdgeClosedError`](EdgeClosedError) when an edge is added to a scope in which the label is already
+/// Returns [EdgeClosedError] when an edge is added to a scope in which the label is already
 /// closed (because `get_edges(s, l, ...)` was called earlier.
 ///
 /// When edges are retrieved (e.g. during query resolution) the `(src, label)` edge is closed.
diff --git a/scopegraphs/src/containers/path.rs b/scopegraphs/src/containers/path.rs
index 043aa39..e3e5c7e 100644
--- a/scopegraphs/src/containers/path.rs
+++ b/scopegraphs/src/containers/path.rs
@@ -1,10 +1,13 @@
 use crate::future_wrapper::FutureWrapper;
 use crate::resolve::{Env, Path, ResolvedPath};
 use futures::future::join_all;
+use std::fmt::Debug;
 use std::hash::Hash;
 
+use super::EnvContainer;
+
 /// Interface for path containers that support the operations required for query resolution.
-pub trait PathContainer<'sg, 'rslv, LABEL: 'sg, DATA: 'sg>: 'rslv {
+pub trait PathContainer<'sg, 'rslv, LABEL: 'sg, DATA: 'sg>: Debug + 'rslv {
     /// Type returned by resolving a path to its sub-environment.
     type EnvContainer;
 
@@ -15,7 +18,26 @@ pub trait PathContainer<'sg, 'rslv, LABEL: 'sg, DATA: 'sg>: 'rslv {
     ) -> Self::EnvContainer;
 }
 
-impl<'rslv, 'sg, LABEL: 'sg, DATA: 'sg> PathContainer<'sg, 'rslv, LABEL, DATA> for Vec<Path<LABEL>>
+/// Trait that is auto-implemented for any [PathContainer] implementation that yields a valid [EnvContainer].
+pub trait PathContainerWf<'sg, 'rslv, LABEL: 'sg, DATA: 'sg, DWFO>:
+    PathContainer<'sg, 'rslv, LABEL, DATA, EnvContainer = Self::EnvContainerWf>
+{
+    /// Witness that ```Self::EnvContainer``` is a valid environment container.
+    type EnvContainerWf: EnvContainer<'sg, 'rslv, LABEL, DATA, DWFO>;
+}
+
+impl<'sg, 'rslv, LABEL, DATA, DWFO, T> PathContainerWf<'sg, 'rslv, LABEL, DATA, DWFO> for T
+where
+    LABEL: Debug + 'sg,
+    DATA: 'sg,
+    T: PathContainer<'sg, 'rslv, LABEL, DATA>,
+    Self::EnvContainer: EnvContainer<'sg, 'rslv, LABEL, DATA, DWFO>,
+{
+    type EnvContainerWf = Self::EnvContainer;
+}
+
+impl<'rslv, 'sg, LABEL: Debug + 'sg, DATA: 'sg> PathContainer<'sg, 'rslv, LABEL, DATA>
+    for Vec<Path<LABEL>>
 where
     Self: 'rslv,
     LABEL: Clone + Hash + Eq,
@@ -30,8 +52,8 @@ where
 
 // TODO: can this be generalized to arbitrary results of PathContainers?
 // (challenge is converting between the different `::EnvContainer`s.)
-impl<'rslv, 'sg, LABEL: 'sg, DATA: 'sg, E: 'rslv> PathContainer<'sg, 'rslv, LABEL, DATA>
-    for Result<Vec<Path<LABEL>>, E>
+impl<'rslv, 'sg, LABEL: Debug + 'sg, DATA: 'sg, E: Debug + 'rslv>
+    PathContainer<'sg, 'rslv, LABEL, DATA> for Result<Vec<Path<LABEL>>, E>
 where
     Self: 'rslv,
     LABEL: Clone + Hash,
diff --git a/scopegraphs/src/containers/scope.rs b/scopegraphs/src/containers/scope.rs
index 2986c4a..3edca07 100644
--- a/scopegraphs/src/containers/scope.rs
+++ b/scopegraphs/src/containers/scope.rs
@@ -1,9 +1,14 @@
+use std::fmt::Debug;
+use std::hash::Hash;
+
 use crate::future_wrapper::FutureWrapper;
 use crate::resolve::Path;
 use crate::Scope;
 
+use super::{PathContainer, PathContainerWf};
+
 /// Interface for scope containers that support the operations required for query resolution.
-pub trait ScopeContainer<LABEL> {
+pub trait ScopeContainer<'sg, 'rslv, LABEL: Debug + 'sg, DATA: 'sg>: Debug {
     /// The type containing paths obtained after stepping to this scope.
     type PathContainer;
 
@@ -14,7 +19,95 @@ pub trait ScopeContainer<LABEL> {
     fn lift_step(self, lbl: LABEL, prefix: Path<LABEL>) -> Self::PathContainer;
 }
 
-impl<LABEL: Copy> ScopeContainer<LABEL> for Vec<Scope> {
+/// Trait that is auto-implemented for any [ScopeContainer] implementation that yields a valid [PathContainer].
+///
+/// This trait is implemented for:
+/// - `Vec<Scope>`,
+/// - [Result] of scope containers, and
+/// - [FutureWrapper] of scope containers.
+/// ```
+/// # use scopegraphs::containers::ScopeContainerWf;
+/// # use scopegraphs::future_wrapper::FutureWrapper;
+/// # use scopegraphs::Scope;
+/// # use std::fmt::Debug;
+/// # use std::hash::Hash;
+///
+/// # trait LBound<'sg>: Copy + Hash + Eq + Debug + 'sg {}
+/// # trait DBound<'sg>: Hash + Eq + 'sg {}
+///
+/// fn test<'sg, 'rslv, LABEL: LBound<'sg>, DATA: DBound<'sg>, DWFO>(
+///     cont: impl ScopeContainerWf<'sg, 'rslv, LABEL, DATA, DWFO>
+/// ) { }
+///
+/// # fn scope_vec<'sg, 'rslv, LABEL: LBound<'sg>, DATA: DBound<'sg>>() {
+///     let vec: Vec<Scope> = todo!();
+///     test::<'_, '_, LABEL, DATA, bool>(vec);
+/// # }
+///
+/// # fn result<'sg, 'rslv, LABEL: LBound<'sg>, DATA: DBound<'sg>, E: Debug + Clone>() {
+///     let result: Result<Vec<Scope>, E> = todo!();
+///     test::<'_, '_, LABEL, DATA, bool>(result);
+///     test::<'_, '_, LABEL, DATA, Result<bool, E>>(result);
+/// # }
+///
+/// # fn future<'sg, 'rslv, LABEL: LBound<'sg>, DATA: DBound<'sg>>() {
+///     let future: FutureWrapper<Vec<Scope>> = todo!();
+///     test::<'_, '_, LABEL, DATA, bool>(future);
+///     test::<'_, '_, LABEL, DATA, FutureWrapper<'_, bool>>(future);
+/// # }
+/// ```
+///
+/// ```no_run
+/// # use scopegraphs::containers::ScopeContainerWf;
+/// # use scopegraphs::Scope;
+/// # use std::fmt::Debug;
+/// # use std::hash::Hash;
+///
+///
+/// fn test<'sg, 'rslv, LABEL: Hash + Eq + Debug + 'sg, DATA: Hash + Eq + 'sg, DWFO>(cont: impl ScopeContainerWf<'sg, 'rslv, LABEL, DATA, DWFO>) {
+///
+/// }
+/// ```
+///
+/// ```no_run
+/// # use scopegraphs::containers::ScopeContainerWf;
+/// # use scopegraphs::Scope;
+/// # use std::fmt::Debug;
+/// # use std::hash::Hash;
+///
+/// test::<'_, '_, (), (), bool>(Result::<_, ()>::Ok(Vec::<Scope>::new()));
+/// test::<'_, '_, (), (), Result<bool, ()>>(Result::<_, ()>::Ok(Vec::<Scope>::new()));
+///
+/// fn test<'sg, 'rslv, LABEL: Hash + Eq + Debug + 'sg, DATA: Hash + Eq + 'sg, DWFO>(cont: impl ScopeContainerWf<'sg, 'rslv, LABEL, DATA, DWFO>) {
+///
+/// }
+/// ```
+///
+pub trait ScopeContainerWf<'sg, 'rslv, LABEL, DATA, DWFO>:
+    ScopeContainer<'sg, 'rslv, LABEL, DATA, PathContainer = Self::PathContainerWf>
+where
+    LABEL: Debug + 'sg,
+    DATA: 'sg,
+{
+    /// Refinement of `Self::PathContainer`, carrying proof that this scope container resolves to valid path containers.
+    type PathContainerWf: PathContainerWf<'sg, 'rslv, LABEL, DATA, DWFO>;
+}
+
+impl<'sg, 'rslv, LABEL, DATA, DWFO, T> ScopeContainerWf<'sg, 'rslv, LABEL, DATA, DWFO> for T
+where
+    LABEL: Debug + 'sg,
+    DATA: 'sg,
+    T: ScopeContainer<'sg, 'rslv, LABEL, DATA>,
+    Self::PathContainer: PathContainerWf<'sg, 'rslv, LABEL, DATA, DWFO>,
+{
+    type PathContainerWf = Self::PathContainer;
+}
+
+impl<'sg: 'rslv, 'rslv, LABEL: Debug + Copy + Eq + Hash + 'sg, DATA: Eq + Hash + 'sg>
+    ScopeContainer<'sg, 'rslv, LABEL, DATA> for Vec<Scope>
+where
+    Vec<Path<LABEL>>: PathContainer<'sg, 'rslv, LABEL, DATA>,
+{
     type PathContainer = Vec<Path<LABEL>>;
 
     fn lift_step(self, lbl: LABEL, prefix: Path<LABEL>) -> Self::PathContainer {
@@ -24,7 +117,17 @@ impl<LABEL: Copy> ScopeContainer<LABEL> for Vec<Scope> {
     }
 }
 
-impl<LABEL, SC: ScopeContainer<LABEL>, E> ScopeContainer<LABEL> for Result<SC, E> {
+impl<
+        'sg: 'rslv,
+        'rslv,
+        LABEL: Debug + Copy + Eq + Hash + 'sg,
+        DATA: Eq + Hash + 'sg,
+        SC: ScopeContainer<'sg, 'rslv, LABEL, DATA>,
+        E: Debug,
+    > ScopeContainer<'sg, 'rslv, LABEL, DATA> for Result<SC, E>
+where
+    Result<SC::PathContainer, E>: PathContainer<'sg, 'rslv, LABEL, DATA>,
+{
     type PathContainer = Result<SC::PathContainer, E>;
 
     fn lift_step(self, lbl: LABEL, prefix: Path<LABEL>) -> Self::PathContainer {
@@ -32,13 +135,18 @@ impl<LABEL, SC: ScopeContainer<LABEL>, E> ScopeContainer<LABEL> for Result<SC, E
     }
 }
 
-impl<'rslv, LABEL, SC: ScopeContainer<LABEL> + Clone> ScopeContainer<LABEL>
-    for FutureWrapper<'rslv, SC>
+impl<
+        'sg: 'rslv,
+        'rslv,
+        LABEL: Debug + Copy + Eq + Hash + 'sg,
+        DATA: Eq + Hash + 'sg,
+        SC: ScopeContainer<'sg, 'rslv, LABEL, DATA> + Clone,
+    > ScopeContainer<'sg, 'rslv, LABEL, DATA> for FutureWrapper<'rslv, SC>
 where
     LABEL: Copy,
-    SC::PathContainer: Clone,
     Self: 'rslv,
     LABEL: 'rslv,
+    SC::PathContainer: Clone,
 {
     type PathContainer = FutureWrapper<'rslv, SC::PathContainer>;
 
diff --git a/scopegraphs/src/future_wrapper.rs b/scopegraphs/src/future_wrapper.rs
index ae0bc49..56ee8a9 100644
--- a/scopegraphs/src/future_wrapper.rs
+++ b/scopegraphs/src/future_wrapper.rs
@@ -1,3 +1,5 @@
+//! Defines a cloneable pointer to a future.
+
 use futures::future::Shared;
 use futures::FutureExt;
 use std::fmt::{Debug, Formatter};
@@ -7,8 +9,8 @@ use std::{
     task::{Context, Poll},
 };
 
-// TODO: fork futures and create our own shared future that can have a
-//       ?Sized inner type (this should be possible)
+// FIXME: only expose futures on tests
+/// Shared pointer to a future, useful to make functions parametric over the type of future they are invoked with.
 pub struct FutureWrapper<'fut, T>(pub Shared<Pin<Box<dyn Future<Output = T> + 'fut>>>);
 
 impl<T> Clone for FutureWrapper<'_, T> {
@@ -18,6 +20,7 @@ impl<T> Clone for FutureWrapper<'_, T> {
 }
 
 impl<'fut, T: Clone> FutureWrapper<'fut, T> {
+    /// Creates shared pointer to `f`.
     pub fn new(f: impl Future<Output = T> + 'fut) -> Self {
         let f: Pin<Box<dyn Future<Output = T> + 'fut>> = Box::pin(f);
         Self(f.shared())
diff --git a/scopegraphs/src/lib.rs b/scopegraphs/src/lib.rs
index 2d753a2..2d8b87e 100644
--- a/scopegraphs/src/lib.rs
+++ b/scopegraphs/src/lib.rs
@@ -29,7 +29,10 @@ pub use scopegraphs_regular_expressions::*;
 
 pub mod completeness;
 pub mod containers;
-mod future_wrapper;
+// #[cfg(test)]
+pub mod future_wrapper;
+// #[cfg(not(test))]
+// mod future_wrapper;
 
 pub mod resolve;
 
diff --git a/scopegraphs/src/resolve/lookup.rs b/scopegraphs/src/resolve/lookup.rs
index fd8dfc6..ee3a3f4 100644
--- a/scopegraphs/src/resolve/lookup.rs
+++ b/scopegraphs/src/resolve/lookup.rs
@@ -13,7 +13,9 @@ use std::rc::Rc;
 use std::sync::Arc;
 
 use crate::completeness::Completeness;
-use crate::containers::{EnvContainer, PathContainer, ScopeContainer};
+use crate::containers::{
+    EnvContainer, PathContainer, PathContainerWf, ScopeContainer, ScopeContainerWf,
+};
 use crate::resolve::{
     DataEquivalence, DataWellformedness, EdgeOrData, Env, LabelOrder, Path, Query, Resolve,
     ResolvedPath,
@@ -28,16 +30,7 @@ where
     LABEL: Label + Copy + Debug + Hash,
     DATA: Debug,
     CMPL: Completeness<LABEL, DATA>,
-    CMPL::GetEdgesResult<'rslv>: ScopeContainer<LABEL>,
-    <CMPL::GetEdgesResult<'rslv> as ScopeContainer<LABEL>>::PathContainer:
-        PathContainer<'sg, 'rslv, LABEL, DATA>,
-    <<CMPL::GetEdgesResult<'rslv> as ScopeContainer<LABEL>>::PathContainer as PathContainer<
-        'sg,
-        'rslv,
-        LABEL,
-        DATA,
-    >>::EnvContainer: EnvContainer<'sg, 'rslv, LABEL, DATA, <DWF as DataWellformedness<'sg, DATA>>::Output>
-        + Debug,
+    CMPL::GetEdgesResult<'rslv>: ScopeContainerWf<'sg, 'rslv, LABEL, DATA, DWF::Output>,
     PWF: for<'a> RegexMatcher<&'a LABEL> + 'rslv,
     DWF: DataWellformedness<'sg, DATA> + 'rslv,
 
@@ -48,7 +41,7 @@ where
     Path<LABEL>: Clone,
 {
     type EnvContainer
-        = EnvC<'sg, 'rslv, CMPL, LABEL, DATA>
+        = EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output>
     where
         'sg: 'rslv,
         Self: 'rslv;
@@ -104,9 +97,14 @@ struct ResolutionContext<'storage, 'sg: 'rslv, 'rslv, LABEL: Label, DATA, CMPL,
     data_equiv: &'rslv DEq,
 }
 
-type EnvC<'sg, 'rslv, CMPL, LABEL, DATA> = <<<CMPL as Completeness<LABEL, DATA>>::GetEdgesResult<
-    'rslv,
-> as ScopeContainer<LABEL>>::PathContainer as PathContainer<'sg, 'rslv, LABEL, DATA>>::EnvContainer;
+type EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWFO> =
+    <<<CMPL as Completeness<LABEL, DATA>>::GetEdgesResult<'rslv> as ScopeContainerWf<
+        'sg,
+        'rslv,
+        LABEL,
+        DATA,
+        DWFO,
+    >>::PathContainerWf as PathContainerWf<'sg, 'rslv, LABEL, DATA, DWFO>>::EnvContainerWf;
 
 type EnvCache<LABEL, ENVC> = RefCell<HashMap<EdgeOrData<LABEL>, Rc<ENVC>>>;
 
@@ -117,16 +115,7 @@ where
     DATA: Debug,
     ResolvedPath<'sg, LABEL, DATA>: Hash + Eq,
     CMPL: Completeness<LABEL, DATA>,
-    CMPL::GetEdgesResult<'rslv>: ScopeContainer<LABEL>,
-    <CMPL::GetEdgesResult<'rslv> as ScopeContainer<LABEL>>::PathContainer:
-        PathContainer<'sg, 'rslv, LABEL, DATA>,
-    <<CMPL::GetEdgesResult<'rslv> as ScopeContainer<LABEL>>::PathContainer as PathContainer<
-        'sg,
-        'rslv,
-        LABEL,
-        DATA,
-    >>::EnvContainer: EnvContainer<'sg, 'rslv, LABEL, DATA, <DWF as DataWellformedness<'sg, DATA>>::Output>
-        + Debug,
+    CMPL::GetEdgesResult<'rslv>: ScopeContainerWf<'sg, 'rslv, LABEL, DATA, DWF::Output>,
     DEq: DataEquivalence<DATA>,
     DWF: DataWellformedness<'sg, DATA>,
     LO: LabelOrder<LABEL>,
@@ -140,7 +129,7 @@ where
         self: &Arc<Self>,
         path_wellformedness: impl for<'a> RegexMatcher<&'a LABEL> + 'rslv,
         path: Path<LABEL>,
-    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA> {
+    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> {
         let edges: Vec<_> = self
             .all_edges
             .iter()
@@ -164,15 +153,15 @@ where
         path_wellformedness: impl for<'a> RegexMatcher<&'a LABEL> + 'rslv,
         edges: &[EdgeOrData<LABEL>],
         path: Path<LABEL>,
-        cache: &EnvCache<LABEL, EnvC<'sg, 'rslv, CMPL, LABEL, DATA>>,
-    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA> {
+        cache: &EnvCache<LABEL, EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output>>,
+    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> {
         // set of labels that are to be resolved last
         let max = self.max(edges);
         let tgt = path.target();
         log::info!("Resolving max-edges {:?} in {:?}", max, tgt);
 
         max.into_iter()
-            .map::<Rc<EnvC<'sg, 'rslv, CMPL, LABEL, DATA>>, _>(|edge| {
+            .map::<Rc<EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output>>, _>(|edge| {
                 if let Some(env) = cache.borrow().get(&edge) {
                     log::info!("Reuse {:?}-environment from cache", edge);
                     return env.clone();
@@ -201,9 +190,9 @@ where
                     let mut merged_env = agg_env.clone();
                     env2.flat_map(move |new_env| {
                         merged_env.merge(new_env);
-                        <EnvC<'sg, 'rslv, CMPL, LABEL, DATA> as From<Env<'sg, LABEL, DATA>>>::from(
-                            merged_env,
-                        )
+                        <EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> as From<
+                            Env<'sg, LABEL, DATA>,
+                        >>::from(merged_env)
                     })
                 })
             })
@@ -220,18 +209,18 @@ where
         edge: EdgeOrData<LABEL>,     // current max label
         edges: &[EdgeOrData<LABEL>], // smaller set of `edge`
         path: Path<LABEL>,
-        cache: &EnvCache<LABEL, EnvC<'sg, 'rslv, CMPL, LABEL, DATA>>,
-    ) -> Rc<EnvC<'sg, 'rslv, CMPL, LABEL, DATA>> {
+        cache: &EnvCache<LABEL, EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output>>,
+    ) -> Rc<EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output>> {
         // base environment
-        let base_env: EnvC<'sg, 'rslv, CMPL, LABEL, DATA> =
+        let base_env: EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> =
             self.resolve_edges(path_wellformedness.clone(), edges, path.clone(), cache);
         let local_self = Arc::clone(self);
         // environment of current (max) label, which might be shadowed by the base environment
         Rc::new(base_env.flat_map(move |base_env| {
             if !base_env.is_empty() && local_self.data_equiv.always_equivalent() {
-                <EnvC<'sg, 'rslv, CMPL, LABEL, DATA> as From<Env<'sg, LABEL, DATA>>>::from(
-                    base_env.clone(),
-                )
+                <EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> as From<
+                        Env<'sg, LABEL, DATA>,
+                    >>::from(base_env.clone())
             } else {
                 let sub_env = local_self.resolve_edge(path_wellformedness.clone(), edge, path);
                 let local_self = Arc::clone(&local_self);
@@ -263,9 +252,9 @@ where
                     for path in filtered_env {
                         new_env.insert(path.clone())
                     }
-                    <EnvC<'sg, 'rslv, CMPL, LABEL, DATA> as From<Env<'sg, LABEL, DATA>>>::from(
-                        new_env,
-                    )
+                    <EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> as From<
+                        Env<'sg, LABEL, DATA>,
+                    >>::from(new_env)
                 })
             }
         }))
@@ -277,7 +266,7 @@ where
         path_wellformedness: impl for<'a> RegexMatcher<&'a LABEL> + 'rslv,
         edge: EdgeOrData<LABEL>,
         path: Path<LABEL>,
-    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA> {
+    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> {
         match edge {
             EdgeOrData::Edge(label) => {
                 let mut new_path_wellformedness = path_wellformedness.clone();
@@ -297,24 +286,25 @@ where
         path_wellformedness: impl for<'a> RegexMatcher<&'a LABEL> + 'rslv,
         label: LABEL,
         path: Path<LABEL>,
-    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA> {
+    ) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> {
         let source = path.target();
         let targets = self.sg.get_edges(source, label);
         let path_set = targets.lift_step(label, path.clone());
         let local_ctx = Arc::clone(self);
-        let env: EnvC<'sg, 'rslv, CMPL, LABEL, DATA> = path_set.map_into_env::<_>(move |p| {
-            local_ctx.resolve_all(path_wellformedness.clone(), p.clone())
-        });
+        let env: EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> =
+            path_set.map_into_env::<_>(move |p| {
+                local_ctx.resolve_all(path_wellformedness.clone(), p.clone())
+            });
         env
     }
 
     /// Creates single-path environment if the data `path.target()` is matching, or an empty environment otherwise.
-    fn resolve_data(&self, path: Path<LABEL>) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA> {
+    fn resolve_data(&self, path: Path<LABEL>) -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> {
         let data = self.sg.get_data(path.target());
         let path = path.clone().resolve(data);
         let data_ok = self.data_wellformedness.data_wf(data);
 
-        <EnvC<'sg, 'rslv, CMPL, LABEL, DATA> as EnvContainer<
+        <EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> as EnvContainer<
             'sg,
             'rslv,
             LABEL,
@@ -351,8 +341,8 @@ where
         smaller
     }
 
-    fn empty_env_container() -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA> {
-        <EnvC<'sg, 'rslv, CMPL, LABEL, DATA> as EnvContainer<
+    fn empty_env_container() -> EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> {
+        <EnvC<'sg, 'rslv, CMPL, LABEL, DATA, DWF::Output> as EnvContainer<
             'sg,
             'rslv,
             LABEL,