diff --git a/crates/ir/src/lib.rs b/crates/ir/src/lib.rs
index 9915bb9..af0bc72 100644
--- a/crates/ir/src/lib.rs
+++ b/crates/ir/src/lib.rs
@@ -117,6 +117,9 @@ pub struct Assumption<T: ProgramInfo> {
 #[cfg_attr(feature = "fuzz", derive_where(Arbitrary; T: ArbitraryProgramInfo))]
 #[cfg_attr(feature = "serde", derive_where(Deserialize, Serialize; T: SerdeProgramInfo))]
 pub struct RuleBody<T: ProgramInfo> {
+    /// Metadata for this rule body.
+    pub meta: T::RuleBodyMeta,
+
     /// The type of each variable.
     ///
     /// Also defines the upper bound on valid variable indices.
@@ -125,11 +128,41 @@ pub struct RuleBody<T: ProgramInfo> {
     /// Maps relation indices to the IDs of loaded relations.
     pub loaded: Vec<T::RelationLabel>,
 
-    /// The inner logic for this rule.
-    pub logic: T::RuleBodyLogic,
+    /// This rule body's expression body.
+    pub body: Expr<T>,
+}
 
-    /// Metadata for this rule body.
-    pub meta: T::RuleBodyMeta,
+#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive_where(PartialOrd, Ord; T: OrdProgramInfo)]
+#[derive_where(Hash; T: HashProgramInfo)]
+#[cfg_attr(feature = "fuzz", derive_where(Arbitrary; T: ArbitraryProgramInfo))]
+#[cfg_attr(feature = "serde", derive_where(Deserialize, Serialize; T: SerdeProgramInfo))]
+pub struct Expr<T: ProgramInfo> {
+    pub meta: T::ExprMeta,
+    pub kind: ExprKind<T>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive_where(PartialOrd, Ord; T: OrdProgramInfo)]
+#[derive_where(Hash; T: HashProgramInfo)]
+#[cfg_attr(feature = "fuzz", derive_where(Arbitrary; T: ArbitraryProgramInfo))]
+#[cfg_attr(feature = "serde", derive_where(Deserialize, Serialize; T: SerdeProgramInfo))]
+pub enum ExprKind<T: ProgramInfo> {
+    Variable(u32),
+    Value(Value),
+    Load {
+        relation: u32,
+        query: Vec<QueryTerm>,
+    },
+    UnaryOp {
+        op: UnaryOpKind,
+        term: Arc<Expr<T>>,
+    },
+    BinaryOp {
+        op: BinaryOpKind,
+        lhs: Arc<Expr<T>>,
+        rhs: Arc<Expr<T>>,
+    },
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -154,27 +187,6 @@ pub enum AssumptionWeight {
     Soft(u32),
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[cfg_attr(feature = "fuzz", derive(Arbitrary))]
-#[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
-pub enum Expr {
-    Variable(u32),
-    Value(Value),
-    Load {
-        relation: u32,
-        query: Vec<QueryTerm>,
-    },
-    UnaryOp {
-        op: UnaryOpKind,
-        term: Arc<Expr>,
-    },
-    BinaryOp {
-        op: BinaryOpKind,
-        lhs: Arc<Expr>,
-        rhs: Arc<Expr>,
-    },
-}
-
 /// Redundant operations (Sub, Neq, Gt, Ge) are not included.
 // TODO: more docs
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -320,8 +332,8 @@ pub trait ProgramInfo: Info {
     /// Metadata for a rule body.
     type RuleBodyMeta: Info;
 
-    /// The type containing the rule body's logic.
-    type RuleBodyLogic: Info;
+    /// Metadata for each expression tree node.
+    type ExprMeta: Info;
 }
 
 /// A blanket trait bounding all associated types in [ProgramInfo].
@@ -338,7 +350,7 @@ macro_rules! def_bound_info {
             AssumptionMeta: $bounds,
             RuleMeta: $bounds,
             RuleBodyMeta: $bounds,
-            RuleBodyLogic: $bounds,
+            ExprMeta: $bounds,
         >
         {
         }
@@ -350,7 +362,7 @@ macro_rules! def_bound_info {
                 AssumptionMeta: $bounds,
                 RuleMeta: $bounds,
                 RuleBodyMeta: $bounds,
-                RuleBodyLogic: $bounds,
+                ExprMeta: $bounds,
             >
         {
         }