Minor changes.

hugr-core/Cargo.toml

@@ -20,6 +20,7 @@ workspace = true
 extension_inference = []
 declarative = ["serde_yaml"]
 model_unstable = ["hugr-model"]
+default = ["model_unstable"]
 
 [[test]]
 name = "model"

hugr-model/capnp/hugr-v0.capnp

@@ -1,7 +1,22 @@
 @0xe02b32c528509601;
 
+# The id of a `Term`.
+using TermId = UInt32;
+
+# Either `0` or the id of a `Term` incremented by one.
+using OptionalTermId = UInt32;
+
+# The id of a `Region`.
+using RegionId = UInt32;
+
+# The id of a `Node`.
+using NodeId = UInt32;
+
+# The id of a `Link`.
+using LinkId = UInt32;
+
 struct Module {
-    root @0 :UInt32;
+    root @0 :RegionId;
     nodes @1 :List(Node);
     regions @2 :List(Region);
     terms @3 :List(Term);
@@ -11,10 +26,10 @@ struct Node {
     operation @0 :Operation;
     inputs @1 :List(LinkRef);
     outputs @2 :List(LinkRef);
-    params @3 :List(UInt32);
-    regions @4 :List(UInt32);
+    params @3 :List(TermId);
+    regions @4 :List(RegionId);
     meta @5 :List(MetaItem);
-    signature @6 :UInt32;
+    signature @6 :OptionalTermId;
 }
 
 struct Operation {
@@ -32,43 +47,43 @@ struct Operation {
         tag @10 :UInt16;
         tailLoop @11 :Void;
         conditional @12 :Void;
-        callFunc @13 :UInt32;
-        loadFunc @14 :UInt32;
+        callFunc @13 :TermId;
+        loadFunc @14 :TermId;
     }
 
     struct FuncDefn {
         name @0 :Text;
         params @1 :List(Param);
-        signature @2 :UInt32;
+        signature @2 :TermId;
     }
 
     struct FuncDecl {
         name @0 :Text;
         params @1 :List(Param);
-        signature @2 :UInt32;
+        signature @2 :TermId;
     }
 
     struct AliasDefn {
         name @0 :Text;
         params @1 :List(Param);
-        type @2 :UInt32;
-        value @3 :UInt32;
+        type @2 :TermId;
+        value @3 :TermId;
     }
 
     struct AliasDecl {
         name @0 :Text;
         params @1 :List(Param);
-        type @2 :UInt32;
+        type @2 :TermId;
     }
 }
 
 struct Region {
     kind @0 :RegionKind;
     sources @1 :List(LinkRef);
     targets @2 :List(LinkRef);
-    children @3 :List(UInt32);
+    children @3 :List(NodeId);
     meta @4 :List(MetaItem);
-    signature @5 :UInt32;
+    signature @5 :OptionalTermId;
 }
 
 enum RegionKind {
@@ -83,14 +98,14 @@ struct MetaItem {
 
 struct LinkRef {
     union {
-        id @0 :UInt32;
+        id @0 :LinkId;
         named @1 :Text;
     }
 }
 
 struct GlobalRef {
     union {
-        node @0 :UInt32;
+        node @0 :NodeId;
         named @1 :Text;
     }
 }
@@ -99,7 +114,7 @@ struct LocalRef {
     union {
         direct :group {
             index @0 :UInt16;
-            node @1 :UInt32;
+            node @1 :NodeId;
         }
         named @2 :Text;
     }
@@ -114,62 +129,62 @@ struct Term {
         variable @4 :LocalRef;
         apply @5 :Apply;
         applyFull @6 :ApplyFull;
-        quote @7 :UInt32;
+        quote @7 :TermId;
         list @8 :ListTerm;
-        listType @9 :UInt32;
+        listType @9 :TermId;
         string @10 :Text;
         stringType @11 :Void;
         nat @12 :UInt64;
         natType @13 :Void;
         extSet @14 :ExtSet;
         extSetType @15 :Void;
-        adt @16 :UInt32;
+        adt @16 :TermId;
         funcType @17 :FuncType;
-        control @18 :UInt32;
+        control @18 :TermId;
         controlType @19 :Void;
     }
 
     struct Apply {
         global @0 :GlobalRef;
-        args @1 :List(UInt32);
+        args @1 :List(TermId);
     }
 
     struct ApplyFull {
         global @0 :GlobalRef;
-        args @1 :List(UInt32);
+        args @1 :List(TermId);
     }
 
     struct ListTerm {
-        items @0 :List(UInt32);
-        tail @1 :UInt32;
+        items @0 :List(TermId);
+        tail @1 :OptionalTermId;
     }
 
     struct ExtSet {
         extensions @0 :List(Text);
-        rest @1 :UInt32;
+        rest @1 :OptionalTermId;
     }
 
     struct FuncType {
-        inputs @0 :UInt32;
-        outputs @1 :UInt32;
-        extensions @2 :UInt32;
+        inputs @0 :TermId;
+        outputs @1 :TermId;
+        extensions @2 :TermId;
     }
 }
 
 struct Param {
     union {
         implicit @0 :Implicit;
         explicit @1 :Explicit;
-        constraint @2 :UInt32;
+        constraint @2 :TermId;
     }
 
     struct Implicit {
         name @0 :Text;
-        type @1 :UInt32;
+        type @1 :TermId;
     }
 
     struct Explicit {
         name @0 :Text;
-        type @1 :UInt32;
+        type @1 :TermId;
     }
 }

hugr-model/src/v0/binary/read.rs

@@ -13,6 +13,7 @@ pub fn read_from_slice<'a>(slice: &[u8], bump: &'a Bump) -> ReadResult<model::Mo
     read_module(bump, root)
 }
 
+/// Read a list of structs from a reader into a slice allocated through the bump allocator.
 macro_rules! read_list {
     ($bump:expr, $reader:expr, $get:ident, $read:expr) => {{
         let mut __list_reader = $reader.$get()?;
@@ -24,6 +25,7 @@ macro_rules! read_list {
     }};
 }
 
+/// Read a list of scalars from a reader into a slice allocated through the bump allocator.
 macro_rules! read_scalar_list {
     ($bump:expr, $reader:expr, $get:ident, $wrap:path) => {{
         let mut __list_reader = $reader.$get()?;

hugr-model/src/v0/binary/write.rs

@@ -1,6 +1,7 @@
 use crate::hugr_v0_capnp as hugr_capnp;
 use crate::v0 as model;
 
+/// Write a list of items into a list builder.
 macro_rules! write_list {
     ($builder:expr, $init:ident, $write:expr, $list:expr) => {
         let mut __list_builder = $builder.reborrow().$init($list.len() as _);

hugr-model/src/v0/mod.rs

@@ -243,6 +243,9 @@ pub struct Node<'a> {
     /// The meta information attached to the node.
     pub meta: &'a [MetaItem<'a>],
     /// The signature of the node.
+    ///
+    /// Can be `None` to indicate that the node's signature should be inferred,
+    /// or for nodes with operations that do not have a signature.
     pub signature: Option<TermId>,
 }
 
@@ -355,6 +358,8 @@ pub struct Region<'a> {
     /// The metadata attached to the region.
     pub meta: &'a [MetaItem<'a>],
     /// The signature of the region.
+    ///
+    /// Can be `None` to indicate that the region signature should be inferred.
     pub signature: Option<TermId>,
 }