Remove more unnecessary parens in printer

20 files changed, 52 insertions, 27 deletions

diff --git a/dhall/src/syntax/ast/expr.rs b/dhall/src/syntax/ast/expr.rs
index 8023771..b53e6cb 100644
--- a/dhall/src/syntax/ast/expr.rs
+++ b/dhall/src/syntax/ast/expr.rs
@@ -258,8 +258,8 @@ impl Expr {
 }
 
 // Empty enum to indicate that no error can occur
-enum X {}
-fn trivial_result<T>(x: Result<T, X>) -> T {
+pub(crate) enum X {}
+pub(crate) fn trivial_result<T>(x: Result<T, X>) -> T {
     match x {
         Ok(x) => x,
         Err(e) => match e {},
diff --git a/dhall/src/syntax/ast/import.rs b/dhall/src/syntax/ast/import.rs
index 75d7946..c45fe51 100644
--- a/dhall/src/syntax/ast/import.rs
+++ b/dhall/src/syntax/ast/import.rs
@@ -1,3 +1,5 @@
+use crate::syntax::trivial_result;
+
 /// The beginning of a file path which anchors subsequent path components
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub enum FilePrefix {
@@ -75,6 +77,12 @@ impl<SE> URL<SE> {
             headers,
         })
     }
+    pub fn map_ref<'a, SE2>(
+        &'a self,
+        f: impl FnOnce(&'a SE) -> SE2,
+    ) -> URL<SE2> {
+        trivial_result(self.traverse_ref(|x| Ok(f(x))))
+    }
 }
 
 impl<SE> ImportTarget<SE> {
@@ -90,6 +98,12 @@ impl<SE> ImportTarget<SE> {
             Missing => Missing,
         })
     }
+    pub fn map_ref<'a, SE2>(
+        &'a self,
+        f: impl FnOnce(&'a SE) -> SE2,
+    ) -> ImportTarget<SE2> {
+        trivial_result(self.traverse_ref(|x| Ok(f(x))))
+    }
 }
 
 impl<SE> Import<SE> {
@@ -103,4 +117,10 @@ impl<SE> Import<SE> {
             hash: self.hash.clone(),
         })
     }
+    pub fn map_ref<'a, SE2>(
+        &'a self,
+        f: impl FnOnce(&'a SE) -> SE2,
+    ) -> Import<SE2> {
+        trivial_result(self.traverse_ref(|x| Ok(f(x))))
+    }
 }
diff --git a/dhall/src/syntax/text/printer.rs b/dhall/src/syntax/text/printer.rs
index e9584bb..2b7bc2e 100644
--- a/dhall/src/syntax/text/printer.rs
+++ b/dhall/src/syntax/text/printer.rs
@@ -8,17 +8,23 @@ use std::fmt::{self, Display};
 // of automatically getting all the parentheses and precedences right.
 #[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
 enum PrintPhase {
+    // `expression`
     Base,
+    // `operator-expression`
     Operator,
+    // All the operator `*-expression`s
     BinOp(ast::BinOp),
+    // `application-expression`
     App,
+    // `import-expression`
     Import,
+    // `primitive-expression`
     Primitive,
 }
 
 // Wraps an Expr with a phase, so that phase selection can be done separate from the actual
 // printing.
-#[derive(Clone)]
+#[derive(Copy, Clone)]
 struct PhasedExpr<'a>(&'a Expr, PrintPhase);
 
 impl<'a> PhasedExpr<'a> {
@@ -58,7 +64,7 @@ impl UnspannedExpr {
             ),
             SomeLit(e) => SomeLit(e.phase(PrintPhase::Import)),
             ExprKind::App(f, a) => ExprKind::App(
-                f.phase(PrintPhase::Import),
+                f.phase(PrintPhase::App),
                 a.phase(PrintPhase::Import),
             ),
             Field(a, b) => Field(a.phase(Primitive), b),
@@ -67,6 +73,9 @@ impl UnspannedExpr {
             Completion(a, b) => {
                 Completion(a.phase(Primitive), b.phase(Primitive))
             }
+            ExprKind::Import(a) => {
+                ExprKind::Import(a.map_ref(|x| x.phase(PrintPhase::Import)))
+            }
             e => e,
         }
     }
@@ -84,7 +93,6 @@ impl UnspannedExpr {
             | Pi(_, _, _)
             | Let(_, _, _, _)
             | EmptyListLit(_)
-            | NEListLit(_)
             | SomeLit(_)
             | Merge(_, _, _)
             | ToMap(_, _)
@@ -92,10 +100,7 @@ impl UnspannedExpr {
             // Precedence is magically handled by the ordering of BinOps.
             ExprKind::BinOp(op, _, _) => phase > PrintPhase::BinOp(*op),
             ExprKind::App(_, _) => phase > PrintPhase::App,
-            Field(_, _)
-            | Projection(_, _)
-            | ProjectionByExpr(_, _)
-            | Completion(_, _) => phase > PrintPhase::Import,
+            Completion(_, _) => phase > PrintPhase::Import,
             _ => false,
         };
 
@@ -413,7 +418,7 @@ impl<SubExpr: Display> Display for Import<SubExpr> {
                     write!(f, "?{}", q)?
                 }
                 if let Some(h) = &url.headers {
-                    write!(f, " using ({})", h)?
+                    write!(f, " using {}", h)?
                 }
             }
             Env(s) => {
diff --git a/dhall/tests/parser/success/annotationsB.txt b/dhall/tests/parser/success/annotationsB.txt
index e4d2113..676d8bb 100644
--- a/dhall/tests/parser/success/annotationsB.txt
+++ b/dhall/tests/parser/success/annotationsB.txt
@@ -1 +1 @@
-([] : List Natural) # ([1, 2, 3]) # (([1, 2, 3]) : List Natural) : List Natural
+([] : List Natural) # [1, 2, 3] # ([1, 2, 3] : List Natural) : List Natural
diff --git a/dhall/tests/parser/success/builtinNameAsFieldB.txt b/dhall/tests/parser/success/builtinNameAsFieldB.txt
index f767e78..a4ecc3a 100644
--- a/dhall/tests/parser/success/builtinNameAsFieldB.txt
+++ b/dhall/tests/parser/success/builtinNameAsFieldB.txt
@@ -1 +1 @@
-let Prelude = https://prelude.dhall-lang.org/package.dhall in (Prelude.`List`).map
+let Prelude = https://prelude.dhall-lang.org/package.dhall in Prelude.`List`.map
diff --git a/dhall/tests/parser/success/fieldsB.txt b/dhall/tests/parser/success/fieldsB.txt
index d091e6d..e709f20 100644
--- a/dhall/tests/parser/success/fieldsB.txt
+++ b/dhall/tests/parser/success/fieldsB.txt
@@ -1 +1 @@
-(({ foo = { bar = { baz = 1 } } }.foo).bar).baz
+{ foo = { bar = { baz = 1 } } }.foo.bar.baz
diff --git a/dhall/tests/parser/success/listB.txt b/dhall/tests/parser/success/listB.txt
index f6d50d0..31a6233 100644
--- a/dhall/tests/parser/success/listB.txt
+++ b/dhall/tests/parser/success/listB.txt
@@ -1 +1 @@
-[[+1, +2, +3], ([+1, +2, +3]) : List Integer, [] : List Integer]
+[[+1, +2, +3], [+1, +2, +3] : List Integer, [] : List Integer]
diff --git a/dhall/tests/parser/success/operatorsB.txt b/dhall/tests/parser/success/operatorsB.txt
index 31db4ce..3f987aa 100644
--- a/dhall/tests/parser/success/operatorsB.txt
+++ b/dhall/tests/parser/success/operatorsB.txt
@@ -1 +1 @@
-{ foo = False && Natural/even (1 + 2 * 3) || True == False != True } ∧ { bar = (["ABC" ++ "DEF"]) # (["GHI"]) } ⫽ { baz = True } : { baz : Bool, foo : Bool } ⩓ { bar : List Text }
+{ foo = False && Natural/even (1 + 2 * 3) || True == False != True } ∧ { bar = ["ABC" ++ "DEF"] # ["GHI"] } ⫽ { baz = True } : { baz : Bool, foo : Bool } ⩓ { bar : List Text }
diff --git a/dhall/tests/parser/success/quotedBoundVariableB.txt b/dhall/tests/parser/success/quotedBoundVariableB.txt
index 6f5b7bf..a9f0499 100644
--- a/dhall/tests/parser/success/quotedBoundVariableB.txt
+++ b/dhall/tests/parser/success/quotedBoundVariableB.txt
@@ -1 +1 @@
-((λ(`Natural/even` : Natural → Bool) → `Natural/even`) Natural/odd) 0
+(λ(`Natural/even` : Natural → Bool) → `Natural/even`) Natural/odd 0
diff --git a/dhall/tests/parser/success/recordProjectionByExpressionB.txt b/dhall/tests/parser/success/recordProjectionByExpressionB.txt
index 14af94f..01ca8c2 100644
--- a/dhall/tests/parser/success/recordProjectionByExpressionB.txt
+++ b/dhall/tests/parser/success/recordProjectionByExpressionB.txt
@@ -1 +1 @@
-let example1 = λ(A : Type) → λ(B : Type) → λ(C : { x : A, y : B }) → C.({ x : A }) : { x : A } in let example2 = λ(A : Type) → λ(B : Type) → λ(C : { p : A, q : B }) → C.(let r = { p : A } in r) : { p : A } in let A = Natural in let B = Text in ((example1 A) B) { x = 10, y = "Text" } ∧ ((example2 A) B) { p = 10, q = "Text" } : { p : A, x : A }
+let example1 = λ(A : Type) → λ(B : Type) → λ(C : { x : A, y : B }) → C.({ x : A }) : { x : A } in let example2 = λ(A : Type) → λ(B : Type) → λ(C : { p : A, q : B }) → C.(let r = { p : A } in r) : { p : A } in let A = Natural in let B = Text in example1 A B { x = 10, y = "Text" } ∧ example2 A B { p = 10, q = "Text" } : { p : A, x : A }
diff --git a/dhall/tests/parser/success/unit/FunctionApplicationMultipleArgsB.txt b/dhall/tests/parser/success/unit/FunctionApplicationMultipleArgsB.txt
index a1b1c55..71bbe20 100644
--- a/dhall/tests/parser/success/unit/FunctionApplicationMultipleArgsB.txt
+++ b/dhall/tests/parser/success/unit/FunctionApplicationMultipleArgsB.txt
@@ -1 +1 @@
-((f x) y) z
+f x y z
diff --git a/dhall/tests/parser/success/unit/ListLitEmptyPrecedenceB.txt b/dhall/tests/parser/success/unit/ListLitEmptyPrecedenceB.txt
index 604143e..74149c2 100644
--- a/dhall/tests/parser/success/unit/ListLitEmptyPrecedenceB.txt
+++ b/dhall/tests/parser/success/unit/ListLitEmptyPrecedenceB.txt
@@ -1 +1 @@
-[] : (List T) U
+[] : List T U
diff --git a/dhall/tests/parser/success/unit/ListLitNonEmptyAnnotatedB.txt b/dhall/tests/parser/success/unit/ListLitNonEmptyAnnotatedB.txt
index 5144935..3e563c7 100644
--- a/dhall/tests/parser/success/unit/ListLitNonEmptyAnnotatedB.txt
+++ b/dhall/tests/parser/success/unit/ListLitNonEmptyAnnotatedB.txt
@@ -1 +1 @@
-([x, y]) : List T
+[x, y] : List T
diff --git a/dhall/tests/parser/success/unit/SomeXYZB.txt b/dhall/tests/parser/success/unit/SomeXYZB.txt
index 42be8b2..8eb59ac 100644
--- a/dhall/tests/parser/success/unit/SomeXYZB.txt
+++ b/dhall/tests/parser/success/unit/SomeXYZB.txt
@@ -1 +1 @@
-((Some x) y) z
+(Some x) y z
diff --git a/dhall/tests/parser/success/unit/import/HeadersB.txt b/dhall/tests/parser/success/unit/import/HeadersB.txt
index 337a497..47eb98e 100644
--- a/dhall/tests/parser/success/unit/import/HeadersB.txt
+++ b/dhall/tests/parser/success/unit/import/HeadersB.txt
@@ -1 +1 @@
-https://example.com/foo using (x)
+https://example.com/foo using x
diff --git a/dhall/tests/parser/success/unit/import/HeadersDoubleHashB.txt b/dhall/tests/parser/success/unit/import/HeadersDoubleHashB.txt
index bf808c8..31e19eb 100644
--- a/dhall/tests/parser/success/unit/import/HeadersDoubleHashB.txt
+++ b/dhall/tests/parser/success/unit/import/HeadersDoubleHashB.txt
@@ -1 +1 @@
-https://example.com/foo using (./headers sha256:0000000000000000000000000000000000000000000000000000000000000000) sha256:1111111111111111111111111111111111111111111111111111111111111111
+https://example.com/foo using ./headers sha256:0000000000000000000000000000000000000000000000000000000000000000 sha256:1111111111111111111111111111111111111111111111111111111111111111
diff --git a/dhall/tests/parser/success/unit/import/HeadersDoubleHashPrecedenceB.txt b/dhall/tests/parser/success/unit/import/HeadersDoubleHashPrecedenceB.txt
index bf808c8..31e19eb 100644
--- a/dhall/tests/parser/success/unit/import/HeadersDoubleHashPrecedenceB.txt
+++ b/dhall/tests/parser/success/unit/import/HeadersDoubleHashPrecedenceB.txt
@@ -1 +1 @@
-https://example.com/foo using (./headers sha256:0000000000000000000000000000000000000000000000000000000000000000) sha256:1111111111111111111111111111111111111111111111111111111111111111
+https://example.com/foo using ./headers sha256:0000000000000000000000000000000000000000000000000000000000000000 sha256:1111111111111111111111111111111111111111111111111111111111111111
diff --git a/dhall/tests/parser/success/unit/import/HeadersHashPrecedenceB.txt b/dhall/tests/parser/success/unit/import/HeadersHashPrecedenceB.txt
index 15d38db..e2d5899 100644
--- a/dhall/tests/parser/success/unit/import/HeadersHashPrecedenceB.txt
+++ b/dhall/tests/parser/success/unit/import/HeadersHashPrecedenceB.txt
@@ -1 +1 @@
-https://example.com/foo using (./headers sha256:0000000000000000000000000000000000000000000000000000000000000000)
+https://example.com/foo using ./headers sha256:0000000000000000000000000000000000000000000000000000000000000000
diff --git a/dhall/tests/parser/success/unit/import/HeadersInteriorHashB.txt b/dhall/tests/parser/success/unit/import/HeadersInteriorHashB.txt
index 15d38db..e2d5899 100644
--- a/dhall/tests/parser/success/unit/import/HeadersInteriorHashB.txt
+++ b/dhall/tests/parser/success/unit/import/HeadersInteriorHashB.txt
@@ -1 +1 @@
-https://example.com/foo using (./headers sha256:0000000000000000000000000000000000000000000000000000000000000000)
+https://example.com/foo using ./headers sha256:0000000000000000000000000000000000000000000000000000000000000000
diff --git a/dhall/tests/parser/success/unit/import/inlineUsingB.txt b/dhall/tests/parser/success/unit/import/inlineUsingB.txt
index 1434d72..b36afc0 100644
--- a/dhall/tests/parser/success/unit/import/inlineUsingB.txt
+++ b/dhall/tests/parser/success/unit/import/inlineUsingB.txt
@@ -1 +1 @@
-https://example.com/foo using ([{ mapKey = "Authorization", mapValue = "token 5199831f4dd3b79e7c5b7e0ebe75d67aa66e79d4" }])
+https://example.com/foo using [{ mapKey = "Authorization", mapValue = "token 5199831f4dd3b79e7c5b7e0ebe75d67aa66e79d4" }]