Split off operations from main expr enum

5 files changed, 171 insertions, 141 deletions

diff --git a/dhall/src/semantics/builtins.rs b/dhall/src/semantics/builtins.rs
index 6007a92..45be448 100644
--- a/dhall/src/semantics/builtins.rs
+++ b/dhall/src/semantics/builtins.rs
@@ -5,8 +5,8 @@ use crate::syntax::map::DupTreeMap;
 use crate::syntax::Const::Type;
 use crate::syntax::{
     BinOp, Builtin, Const, Expr, ExprKind, InterpolatedText,
-    InterpolatedTextContents, Label, NaiveDouble, NumKind, Span, UnspannedExpr,
-    V,
+    InterpolatedTextContents, Label, NaiveDouble, NumKind, OpKind, Span,
+    UnspannedExpr, V,
 };
 use std::collections::HashMap;
 use std::convert::TryInto;
@@ -34,10 +34,10 @@ impl BuiltinClosure {
         HirKind::Expr(self.args.iter().fold(
             ExprKind::Builtin(self.b),
             |acc, v| {
-                ExprKind::App(
+                ExprKind::Op(OpKind::App(
                     Hir::new(HirKind::Expr(acc), Span::Artificial),
                     v.to_hir(venv),
-                )
+                ))
             },
         ))
     }
@@ -59,16 +59,16 @@ macro_rules! make_type {
         rc(ExprKind::Var(V(stringify!($var).into(), 0)))
     };
     (Optional $ty:ident) => {
-        rc(ExprKind::App(
+        rc(ExprKind::Op(OpKind::App(
             rc(ExprKind::Builtin(Builtin::Optional)),
             make_type!($ty)
-        ))
+        )))
     };
     (List $($rest:tt)*) => {
-        rc(ExprKind::App(
+        rc(ExprKind::Op(OpKind::App(
             rc(ExprKind::Builtin(Builtin::List)),
             make_type!($($rest)*)
-        ))
+        )))
     };
     ({ $($label:ident : $ty:ident),* }) => {{
         let mut kts = DupTreeMap::new();
@@ -214,10 +214,10 @@ macro_rules! make_closure {
     };
     (List $($ty:tt)*) => {{
         let ty = make_closure!($($ty)*);
-        rc(ExprKind::App(
+        rc(ExprKind::Op(OpKind::App(
             rc(ExprKind::Builtin(Builtin::List)),
             ty
-        ))
+        )))
     }};
     (Some($($v:tt)*)) => {
         rc(ExprKind::SomeLit(
@@ -225,20 +225,20 @@ macro_rules! make_closure {
         ))
     };
     (1 + $($v:tt)*) => {
-        rc(ExprKind::BinOp(
+        rc(ExprKind::Op(OpKind::BinOp(
             BinOp::NaturalPlus,
             make_closure!($($v)*),
             rc(ExprKind::Num(NumKind::Natural(1)))
-        ))
+        )))
     };
     ([ $($head:tt)* ] # $($tail:tt)*) => {{
         let head = make_closure!($($head)*);
         let tail = make_closure!($($tail)*);
-        rc(ExprKind::BinOp(
+        rc(ExprKind::Op(OpKind::BinOp(
             BinOp::ListAppend,
             rc(ExprKind::NEListLit(vec![head])),
             tail,
-        ))
+        )))
     }};
 }
 
diff --git a/dhall/src/semantics/nze/nir.rs b/dhall/src/semantics/nze/nir.rs
index e0d227e..73c3f30 100644
--- a/dhall/src/semantics/nze/nir.rs
+++ b/dhall/src/semantics/nze/nir.rs
@@ -8,7 +8,7 @@ use crate::semantics::{
 };
 use crate::syntax::{
     BinOp, Builtin, Const, Expr, ExprKind, InterpolatedTextContents, Label,
-    NumKind, Span,
+    NumKind, OpKind, Span,
 };
 use crate::ToExprOptions;
 
@@ -190,24 +190,24 @@ impl Nir {
                 NirKind::Const(c) => ExprKind::Const(*c),
                 NirKind::BuiltinType(b) => ExprKind::Builtin(*b),
                 NirKind::Num(l) => ExprKind::Num(l.clone()),
-                NirKind::OptionalType(t) => ExprKind::App(
+                NirKind::OptionalType(t) => ExprKind::Op(OpKind::App(
                     Nir::from_builtin(Builtin::Optional).to_hir(venv),
                     t.to_hir(venv),
-                ),
-                NirKind::EmptyOptionalLit(n) => ExprKind::App(
+                )),
+                NirKind::EmptyOptionalLit(n) => ExprKind::Op(OpKind::App(
                     Nir::from_builtin(Builtin::OptionalNone).to_hir(venv),
                     n.to_hir(venv),
-                ),
+                )),
                 NirKind::NEOptionalLit(n) => ExprKind::SomeLit(n.to_hir(venv)),
-                NirKind::ListType(t) => ExprKind::App(
+                NirKind::ListType(t) => ExprKind::Op(OpKind::App(
                     Nir::from_builtin(Builtin::List).to_hir(venv),
                     t.to_hir(venv),
-                ),
+                )),
                 NirKind::EmptyListLit(n) => ExprKind::EmptyListLit(Hir::new(
-                    HirKind::Expr(ExprKind::App(
+                    HirKind::Expr(ExprKind::Op(OpKind::App(
                         Nir::from_builtin(Builtin::List).to_hir(venv),
                         n.to_hir(venv),
-                    )),
+                    ))),
                     Span::Artificial,
                 )),
                 NirKind::NEListLit(elts) => ExprKind::NEListLit(
@@ -229,31 +229,33 @@ impl Nir {
                         .collect(),
                 ),
                 NirKind::UnionType(kts) => map_uniontype(kts),
-                NirKind::UnionConstructor(l, kts) => ExprKind::Field(
-                    Hir::new(
-                        HirKind::Expr(map_uniontype(kts)),
-                        Span::Artificial,
-                    ),
-                    l.clone(),
-                ),
-                NirKind::UnionLit(l, v, kts) => ExprKind::App(
+                NirKind::UnionConstructor(l, kts) => {
+                    ExprKind::Op(OpKind::Field(
+                        Hir::new(
+                            HirKind::Expr(map_uniontype(kts)),
+                            Span::Artificial,
+                        ),
+                        l.clone(),
+                    ))
+                }
+                NirKind::UnionLit(l, v, kts) => ExprKind::Op(OpKind::App(
                     Hir::new(
-                        HirKind::Expr(ExprKind::Field(
+                        HirKind::Expr(ExprKind::Op(OpKind::Field(
                             Hir::new(
                                 HirKind::Expr(map_uniontype(kts)),
                                 Span::Artificial,
                             ),
                             l.clone(),
-                        )),
+                        ))),
                         Span::Artificial,
                     ),
                     v.to_hir(venv),
-                ),
-                NirKind::Equivalence(x, y) => ExprKind::BinOp(
+                )),
+                NirKind::Equivalence(x, y) => ExprKind::Op(OpKind::BinOp(
                     BinOp::Equivalence,
                     x.to_hir(venv),
                     y.to_hir(venv),
-                ),
+                )),
                 NirKind::PartialExpr(e) => e.map_ref(|v| v.to_hir(venv)),
             }),
         };
diff --git a/dhall/src/semantics/nze/normalize.rs b/dhall/src/semantics/nze/normalize.rs
index 570e106..ebf4ae1 100644
--- a/dhall/src/semantics/nze/normalize.rs
+++ b/dhall/src/semantics/nze/normalize.rs
@@ -3,7 +3,9 @@ use std::collections::HashMap;
 
 use crate::semantics::NzEnv;
 use crate::semantics::{Binder, Closure, Hir, HirKind, Nir, NirKind, TextLit};
-use crate::syntax::{BinOp, ExprKind, InterpolatedTextContents, NumKind};
+use crate::syntax::{
+    BinOp, ExprKind, InterpolatedTextContents, NumKind, OpKind,
+};
 
 pub fn apply_any(f: Nir, a: Nir) -> NirKind {
     match f.kind() {
@@ -12,7 +14,7 @@ pub fn apply_any(f: Nir, a: Nir) -> NirKind {
         NirKind::UnionConstructor(l, kts) => {
             NirKind::UnionLit(l.clone(), a, kts.clone())
         }
-        _ => NirKind::PartialExpr(ExprKind::App(f, a)),
+        _ => NirKind::PartialExpr(ExprKind::Op(OpKind::App(f, a))),
     }
 }
 
@@ -173,11 +175,11 @@ fn apply_binop<'a>(o: BinOp, x: &'a Nir, y: &'a Nir) -> Option<Ret<'a>> {
         }
         (RecursiveRecordMerge, RecordLit(kvs1), RecordLit(kvs2)) => {
             let kvs = merge_maps(kvs1, kvs2, |_, v1, v2| {
-                Nir::from_partial_expr(ExprKind::BinOp(
+                Nir::from_partial_expr(ExprKind::Op(OpKind::BinOp(
                     RecursiveRecordMerge,
                     v1.clone(),
                     v2.clone(),
-                ))
+                )))
             });
             Ret::NirKind(RecordLit(kvs))
         }
@@ -188,11 +190,11 @@ fn apply_binop<'a>(o: BinOp, x: &'a Nir, y: &'a Nir) -> Option<Ret<'a>> {
                 kts_y,
                 // If the Label exists for both records, then we hit the recursive case.
                 |_, l: &Nir, r: &Nir| {
-                    Nir::from_partial_expr(ExprKind::BinOp(
+                    Nir::from_partial_expr(ExprKind::Op(OpKind::BinOp(
                         RecursiveRecordTypeMerge,
                         l.clone(),
                         r.clone(),
-                    ))
+                    )))
                 },
             );
             Ret::NirKind(RecordType(kts))
@@ -216,7 +218,7 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
     use NumKind::Bool;
 
     let ret = match expr {
-        ExprKind::Import(..) | ExprKind::Completion(..) => {
+        ExprKind::Import(..) | ExprKind::Op(OpKind::Completion(..)) => {
             unreachable!("This case should have been handled in resolution")
         }
         ExprKind::Var(..)
@@ -230,7 +232,7 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
         ExprKind::Const(c) => Ret::Nir(Nir::from_const(c)),
         ExprKind::Builtin(b) => Ret::Nir(Nir::from_builtin_env(b, env)),
         ExprKind::Assert(_) => Ret::Expr(expr),
-        ExprKind::App(v, a) => Ret::Nir(v.app(a)),
+        ExprKind::Op(OpKind::App(v, a)) => Ret::Nir(v.app(a)),
         ExprKind::Num(l) => Ret::NirKind(Num(l)),
         ExprKind::SomeLit(e) => Ret::NirKind(NEOptionalLit(e)),
         ExprKind::EmptyListLit(t) => {
@@ -261,7 +263,7 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
                 Ret::NirKind(NirKind::TextLit(tlit))
             }
         }
-        ExprKind::BoolIf(ref b, ref e1, ref e2) => {
+        ExprKind::Op(OpKind::BoolIf(ref b, ref e1, ref e2)) => {
             match b.kind() {
                 Num(Bool(true)) => Ret::NirRef(e1),
                 Num(Bool(false)) => Ret::NirRef(e2),
@@ -275,12 +277,14 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
                 }
             }
         }
-        ExprKind::BinOp(o, ref x, ref y) => match apply_binop(o, x, y) {
-            Some(ret) => ret,
-            None => Ret::Expr(expr),
-        },
+        ExprKind::Op(OpKind::BinOp(o, ref x, ref y)) => {
+            match apply_binop(o, x, y) {
+                Some(ret) => ret,
+                None => Ret::Expr(expr),
+            }
+        }
 
-        ExprKind::Field(ref v, ref field) => match v.kind() {
+        ExprKind::Op(OpKind::Field(ref v, ref field)) => match v.kind() {
             RecordLit(kvs) => match kvs.get(field) {
                 Some(r) => Ret::Nir(r.clone()),
                 None => Ret::Expr(expr),
@@ -288,53 +292,65 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
             UnionType(kts) => {
                 Ret::NirKind(UnionConstructor(field.clone(), kts.clone()))
             }
-            PartialExpr(ExprKind::Projection(x, _)) => {
+            PartialExpr(ExprKind::Op(OpKind::Projection(x, _))) => {
                 return normalize_one_layer(
-                    ExprKind::Field(x.clone(), field.clone()),
+                    ExprKind::Op(OpKind::Field(x.clone(), field.clone())),
                     env,
                 )
             }
-            PartialExpr(ExprKind::BinOp(
+            PartialExpr(ExprKind::Op(OpKind::BinOp(
                 BinOp::RightBiasedRecordMerge,
                 x,
                 y,
-            )) => match (x.kind(), y.kind()) {
+            ))) => match (x.kind(), y.kind()) {
                 (_, RecordLit(kvs)) => match kvs.get(field) {
                     Some(r) => Ret::Nir(r.clone()),
                     None => {
                         return normalize_one_layer(
-                            ExprKind::Field(x.clone(), field.clone()),
+                            ExprKind::Op(OpKind::Field(
+                                x.clone(),
+                                field.clone(),
+                            )),
                             env,
                         )
                     }
                 },
                 (RecordLit(kvs), _) => match kvs.get(field) {
-                    Some(r) => Ret::Expr(ExprKind::Field(
-                        Nir::from_kind(PartialExpr(ExprKind::BinOp(
-                            BinOp::RightBiasedRecordMerge,
-                            Nir::from_kind(RecordLit(
-                                Some((field.clone(), r.clone()))
-                                    .into_iter()
-                                    .collect(),
-                            )),
-                            y.clone(),
+                    Some(r) => Ret::Expr(ExprKind::Op(OpKind::Field(
+                        Nir::from_kind(PartialExpr(ExprKind::Op(
+                            OpKind::BinOp(
+                                BinOp::RightBiasedRecordMerge,
+                                Nir::from_kind(RecordLit(
+                                    Some((field.clone(), r.clone()))
+                                        .into_iter()
+                                        .collect(),
+                                )),
+                                y.clone(),
+                            ),
                         ))),
                         field.clone(),
-                    )),
+                    ))),
                     None => {
                         return normalize_one_layer(
-                            ExprKind::Field(y.clone(), field.clone()),
+                            ExprKind::Op(OpKind::Field(
+                                y.clone(),
+                                field.clone(),
+                            )),
                             env,
                         )
                     }
                 },
                 _ => Ret::Expr(expr),
             },
-            PartialExpr(ExprKind::BinOp(BinOp::RecursiveRecordMerge, x, y)) => {
-                match (x.kind(), y.kind()) {
-                    (RecordLit(kvs), _) => match kvs.get(field) {
-                        Some(r) => Ret::Expr(ExprKind::Field(
-                            Nir::from_kind(PartialExpr(ExprKind::BinOp(
+            PartialExpr(ExprKind::Op(OpKind::BinOp(
+                BinOp::RecursiveRecordMerge,
+                x,
+                y,
+            ))) => match (x.kind(), y.kind()) {
+                (RecordLit(kvs), _) => match kvs.get(field) {
+                    Some(r) => Ret::Expr(ExprKind::Op(OpKind::Field(
+                        Nir::from_kind(PartialExpr(ExprKind::Op(
+                            OpKind::BinOp(
                                 BinOp::RecursiveRecordMerge,
                                 Nir::from_kind(RecordLit(
                                     Some((field.clone(), r.clone()))
@@ -342,19 +358,24 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
                                         .collect(),
                                 )),
                                 y.clone(),
-                            ))),
-                            field.clone(),
-                        )),
-                        None => {
-                            return normalize_one_layer(
-                                ExprKind::Field(y.clone(), field.clone()),
-                                env,
-                            )
-                        }
-                    },
-                    (_, RecordLit(kvs)) => match kvs.get(field) {
-                        Some(r) => Ret::Expr(ExprKind::Field(
-                            Nir::from_kind(PartialExpr(ExprKind::BinOp(
+                            ),
+                        ))),
+                        field.clone(),
+                    ))),
+                    None => {
+                        return normalize_one_layer(
+                            ExprKind::Op(OpKind::Field(
+                                y.clone(),
+                                field.clone(),
+                            )),
+                            env,
+                        )
+                    }
+                },
+                (_, RecordLit(kvs)) => match kvs.get(field) {
+                    Some(r) => Ret::Expr(ExprKind::Op(OpKind::Field(
+                        Nir::from_kind(PartialExpr(ExprKind::Op(
+                            OpKind::BinOp(
                                 BinOp::RecursiveRecordMerge,
                                 x.clone(),
                                 Nir::from_kind(RecordLit(
@@ -362,52 +383,57 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
                                         .into_iter()
                                         .collect(),
                                 )),
-                            ))),
-                            field.clone(),
-                        )),
-                        None => {
-                            return normalize_one_layer(
-                                ExprKind::Field(x.clone(), field.clone()),
-                                env,
-                            )
-                        }
-                    },
-                    _ => Ret::Expr(expr),
-                }
-            }
+                            ),
+                        ))),
+                        field.clone(),
+                    ))),
+                    None => {
+                        return normalize_one_layer(
+                            ExprKind::Op(OpKind::Field(
+                                x.clone(),
+                                field.clone(),
+                            )),
+                            env,
+                        )
+                    }
+                },
+                _ => Ret::Expr(expr),
+            },
             _ => Ret::Expr(expr),
         },
-        ExprKind::Projection(_, ref ls) if ls.is_empty() => {
+        ExprKind::Op(OpKind::Projection(_, ref ls)) if ls.is_empty() => {
             Ret::NirKind(RecordLit(HashMap::new()))
         }
-        ExprKind::Projection(ref v, ref ls) => match v.kind() {
+        ExprKind::Op(OpKind::Projection(ref v, ref ls)) => match v.kind() {
             RecordLit(kvs) => Ret::NirKind(RecordLit(
                 ls.iter()
                     .filter_map(|l| kvs.get(l).map(|x| (l.clone(), x.clone())))
                     .collect(),
             )),
-            PartialExpr(ExprKind::Projection(v2, _)) => {
+            PartialExpr(ExprKind::Op(OpKind::Projection(v2, _))) => {
                 return normalize_one_layer(
-                    ExprKind::Projection(v2.clone(), ls.clone()),
+                    ExprKind::Op(OpKind::Projection(v2.clone(), ls.clone())),
                     env,
                 )
             }
             _ => Ret::Expr(expr),
         },
-        ExprKind::ProjectionByExpr(ref v, ref t) => match t.kind() {
-            RecordType(kts) => {
-                return normalize_one_layer(
-                    ExprKind::Projection(
-                        v.clone(),
-                        kts.keys().cloned().collect(),
-                    ),
-                    env,
-                )
+        ExprKind::Op(OpKind::ProjectionByExpr(ref v, ref t)) => {
+            match t.kind() {
+                RecordType(kts) => {
+                    return normalize_one_layer(
+                        ExprKind::Op(OpKind::Projection(
+                            v.clone(),
+                            kts.keys().cloned().collect(),
+                        )),
+                        env,
+                    )
+                }
+                _ => Ret::Expr(expr),
             }
-            _ => Ret::Expr(expr),
-        },
+        }
 
-        ExprKind::Merge(ref handlers, ref variant, _) => {
+        ExprKind::Op(OpKind::Merge(ref handlers, ref variant, _)) => {
             match handlers.kind() {
                 RecordLit(kvs) => match variant.kind() {
                     UnionConstructor(l, _) => match kvs.get(l) {
@@ -431,7 +457,7 @@ pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
                 _ => Ret::Expr(expr),
             }
         }
-        ExprKind::ToMap(ref v, ref annot) => match v.kind() {
+        ExprKind::Op(OpKind::ToMap(ref v, ref annot)) => match v.kind() {
             RecordLit(kvs) if kvs.is_empty() => {
                 match annot.as_ref().map(|v| v.kind()) {
                     Some(NirKind::ListType(t)) => {
diff --git a/dhall/src/semantics/resolve/resolve.rs b/dhall/src/semantics/resolve/resolve.rs
index 6e50fa6..3e0022f 100644
--- a/dhall/src/semantics/resolve/resolve.rs
+++ b/dhall/src/semantics/resolve/resolve.rs
@@ -11,7 +11,7 @@ use crate::syntax;
 use crate::syntax::map::DupTreeMap;
 use crate::syntax::{
     BinOp, Builtin, Expr, ExprKind, FilePath, FilePrefix, Hash, ImportMode,
-    ImportTarget, Span, UnspannedExpr, URL,
+    ImportTarget, OpKind, Span, UnspannedExpr, URL,
 };
 use crate::{Parsed, Resolved};
 
@@ -179,12 +179,13 @@ impl ImportLocation {
         };
 
         let asloc_ty = make_aslocation_uniontype();
-        let expr = mkexpr(ExprKind::Field(asloc_ty, field_name.into()));
+        let expr =
+            mkexpr(ExprKind::Op(OpKind::Field(asloc_ty, field_name.into())));
         match arg {
-            Some(arg) => mkexpr(ExprKind::App(
+            Some(arg) => mkexpr(ExprKind::Op(OpKind::App(
                 expr,
                 mkexpr(ExprKind::TextLit(arg.into())),
-            )),
+            ))),
             None => expr,
         }
     }
@@ -261,21 +262,21 @@ fn resolve_one_import(
 /// Desugar the first level of the expression.
 fn desugar(expr: &Expr) -> Cow<'_, Expr> {
     match expr.kind() {
-        ExprKind::Completion(ty, compl) => {
+        ExprKind::Op(OpKind::Completion(ty, compl)) => {
             let ty_field_default = Expr::new(
-                ExprKind::Field(ty.clone(), "default".into()),
+                ExprKind::Op(OpKind::Field(ty.clone(), "default".into())),
                 expr.span(),
             );
             let merged = Expr::new(
-                ExprKind::BinOp(
+                ExprKind::Op(OpKind::BinOp(
                     BinOp::RightBiasedRecordMerge,
                     ty_field_default,
                     compl.clone(),
-                ),
+                )),
                 expr.span(),
             );
             let ty_field_type = Expr::new(
-                ExprKind::Field(ty.clone(), "Type".into()),
+                ExprKind::Op(OpKind::Field(ty.clone(), "Type".into())),
                 expr.span(),
             );
             Cow::Owned(Expr::new(
@@ -304,7 +305,7 @@ fn traverse_resolve_expr(
                     .format(),
             )?,
         },
-        ExprKind::BinOp(BinOp::ImportAlt, l, r) => {
+        ExprKind::Op(OpKind::BinOp(BinOp::ImportAlt, l, r)) => {
             match traverse_resolve_expr(name_env, l, f) {
                 Ok(l) => l,
                 Err(_) => {
diff --git a/dhall/src/semantics/tck/typecheck.rs b/dhall/src/semantics/tck/typecheck.rs
index c3334b5..8f3fcb2 100644
--- a/dhall/src/semantics/tck/typecheck.rs
+++ b/dhall/src/semantics/tck/typecheck.rs
@@ -9,7 +9,8 @@ use crate::semantics::{
     Type,
 };
 use crate::syntax::{
-    BinOp, Builtin, Const, ExprKind, InterpolatedTextContents, NumKind, Span,
+    BinOp, Builtin, Const, ExprKind, InterpolatedTextContents, NumKind, OpKind,
+    Span,
 };
 
 fn check_rectymerge(
@@ -75,7 +76,7 @@ fn type_one_layer(
     let span_err = |msg: &str| mk_span_err(span.clone(), msg);
 
     let ty = match &ekind {
-        ExprKind::Import(..) | ExprKind::Completion(..) => {
+        ExprKind::Import(..) | ExprKind::Op(OpKind::Completion(..)) => {
             unreachable!("This case should have been handled in resolution")
         }
         ExprKind::Var(..)
@@ -222,7 +223,7 @@ fn type_one_layer(
 
             Type::from_const(k)
         }
-        ExprKind::Field(scrut, x) => {
+        ExprKind::Op(OpKind::Field(scrut, x)) => {
             match scrut.ty().kind() {
                 NirKind::RecordType(kts) => match kts.get(&x) {
                     Some(val) => Type::new_infer_universe(env, val.clone())?,
@@ -261,7 +262,7 @@ fn type_one_layer(
             }
             t
         }
-        ExprKind::App(f, arg) => {
+        ExprKind::Op(OpKind::App(f, arg)) => {
             match f.ty().kind() {
                 // TODO: store Type in closure
                 NirKind::PiClosure { annot, closure, .. } => {
@@ -309,7 +310,7 @@ fn type_one_layer(
                 ),
             }
         }
-        ExprKind::BoolIf(x, y, z) => {
+        ExprKind::Op(OpKind::BoolIf(x, y, z)) => {
             if *x.ty().kind() != NirKind::from_builtin(Builtin::Bool) {
                 return span_err("InvalidPredicate");
             }
@@ -322,7 +323,7 @@ fn type_one_layer(
 
             y.ty().clone()
         }
-        ExprKind::BinOp(BinOp::RightBiasedRecordMerge, x, y) => {
+        ExprKind::Op(OpKind::BinOp(BinOp::RightBiasedRecordMerge, x, y)) => {
             let x_type = x.ty();
             let y_type = y.ty();
 
@@ -344,22 +345,22 @@ fn type_one_layer(
             let u = max(x.ty().ty(), y.ty().ty());
             Nir::from_kind(NirKind::RecordType(kts)).to_type(u)
         }
-        ExprKind::BinOp(BinOp::RecursiveRecordMerge, x, y) => {
+        ExprKind::Op(OpKind::BinOp(BinOp::RecursiveRecordMerge, x, y)) => {
             check_rectymerge(&span, env, x.ty().to_nir(), y.ty().to_nir())?;
 
             let hir = Hir::new(
-                HirKind::Expr(ExprKind::BinOp(
+                HirKind::Expr(ExprKind::Op(OpKind::BinOp(
                     BinOp::RecursiveRecordTypeMerge,
                     x.ty().to_hir(env.as_varenv()),
                     y.ty().to_hir(env.as_varenv()),
-                )),
+                ))),
                 span.clone(),
             );
             let x_u = x.ty().ty();
             let y_u = y.ty().ty();
             Type::new(hir.eval(env), max(x_u, y_u))
         }
-        ExprKind::BinOp(BinOp::RecursiveRecordTypeMerge, x, y) => {
+        ExprKind::Op(OpKind::BinOp(BinOp::RecursiveRecordTypeMerge, x, y)) => {
             check_rectymerge(&span, env, x.eval(env), y.eval(env))?;
 
             // A RecordType's type is always a const
@@ -367,7 +368,7 @@ fn type_one_layer(
             let yk = y.ty().as_const().unwrap();
             Type::from_const(max(xk, yk))
         }
-        ExprKind::BinOp(BinOp::ListAppend, l, r) => {
+        ExprKind::Op(OpKind::BinOp(BinOp::ListAppend, l, r)) => {
             match l.ty().kind() {
                 NirKind::ListType(..) => {}
                 _ => return span_err("BinOpTypeMismatch"),
@@ -379,7 +380,7 @@ fn type_one_layer(
 
             l.ty().clone()
         }
-        ExprKind::BinOp(BinOp::Equivalence, l, r) => {
+        ExprKind::Op(OpKind::BinOp(BinOp::Equivalence, l, r)) => {
             if l.ty() != r.ty() {
                 return span_err("EquivalenceTypeMismatch");
             }
@@ -389,7 +390,7 @@ fn type_one_layer(
 
             Type::from_const(Const::Type)
         }
-        ExprKind::BinOp(o, l, r) => {
+        ExprKind::Op(OpKind::BinOp(o, l, r)) => {
             let t = Type::from_builtin(match o {
                 BinOp::BoolAnd
                 | BinOp::BoolOr
@@ -415,7 +416,7 @@ fn type_one_layer(
 
             t
         }
-        ExprKind::Merge(record, union, type_annot) => {
+        ExprKind::Op(OpKind::Merge(record, union, type_annot)) => {
             let record_type = record.ty();
             let handlers = match record_type.kind() {
                 NirKind::RecordType(kts) => kts,
@@ -554,7 +555,7 @@ fn type_one_layer(
                 (None, None) => return span_err("MergeEmptyNeedsAnnotation"),
             }
         }
-        ExprKind::ToMap(record, annot) => {
+        ExprKind::Op(OpKind::ToMap(record, annot)) => {
             if record.ty().ty().as_const() != Some(Const::Type) {
                 return span_err("`toMap` only accepts records of type `Type`");
             }
@@ -624,7 +625,7 @@ fn type_one_layer(
                 output_type
             }
         }
-        ExprKind::Projection(record, labels) => {
+        ExprKind::Op(OpKind::Projection(record, labels)) => {
             let record_type = record.ty();
             let kts = match record_type.kind() {
                 NirKind::RecordType(kts) => kts,
@@ -652,7 +653,7 @@ fn type_one_layer(
                 Nir::from_kind(NirKind::RecordType(new_kts)),
             )?
         }
-        ExprKind::ProjectionByExpr(record, selection) => {
+        ExprKind::Op(OpKind::ProjectionByExpr(record, selection)) => {
             let record_type = record.ty();
             let rec_kts = match record_type.kind() {
                 NirKind::RecordType(kts) => kts,