2 files changed, 18 insertions, 18 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 45e31095c..4b150ef06 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -1042,30 +1042,18 @@ impl Type {
     }
 
     pub fn is_bool(&self) -> bool {
-        match &self.ty.value {
-            Ty::Apply(a_ty) => match a_ty.ctor {
-                TypeCtor::Bool => true,
-                _ => false,
-            },
-            _ => false,
-        }
+        matches!(self.ty.value, Ty::Apply(ApplicationTy { ctor: TypeCtor::Bool, .. }))
     }
 
     pub fn is_mutable_reference(&self) -> bool {
-        match &self.ty.value {
-            Ty::Apply(a_ty) => match a_ty.ctor {
-                TypeCtor::Ref(Mutability::Mut) => true,
-                _ => false,
-            },
-            _ => false,
-        }
+        matches!(
+            self.ty.value,
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Ref(Mutability::Mut), .. })
+        )
     }
 
     pub fn is_unknown(&self) -> bool {
-        match &self.ty.value {
-            Ty::Unknown => true,
-            _ => false,
-        }
+        matches!(self.ty.value, Ty::Unknown)
     }
 
     /// Checks that particular type `ty` implements `std::future::Future`.
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 9f59d590c..713d45f48 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -4,6 +4,18 @@
 //! The principal difference between HIR and syntax trees is that HIR is bound
 //! to a particular crate instance. That is, it has cfg flags and features
 //! applied. So, the relation between syntax and HIR is many-to-one.
+//!
+//! HIR is the public API of the all of the compiler logic above syntax trees.
+//! It is written in "OO" style. Each type is self contained (as in, it knows it's
+//! parents and full context). It should be "clean code".
+//!
+//! `ra_hir_*` crates are the implementation of the compiler logic.
+//! They are written in "ECS" style, with relatively little abstractions.
+//! Many types are not self-contained, and explicitly use local indexes, arenas, etc.
+//!
+//! `ra_hir` is what insulates the "we don't know how to actually write an incremental compiler"
+//! from the ide with completions, hovers, etc. It is a (soft, internal) boundary:
+//! https://www.tedinski.com/2018/02/06/system-boundaries.html.
 
 #![recursion_limit = "512"]