Add a few more pretty errors

12 files changed, 46 insertions, 18 deletions

diff --git a/dhall/src/core/value.rs b/dhall/src/core/value.rs
index 61c7015..d4f5131 100644
--- a/dhall/src/core/value.rs
+++ b/dhall/src/core/value.rs
@@ -165,6 +165,9 @@ impl Value {
             _ => None,
         }
     }
+    pub(crate) fn span(&self) -> Span {
+        self.as_internal().span.clone()
+    }
 
     fn as_internal(&self) -> Ref<ValueInternal> {
         self.0.borrow()
diff --git a/dhall/src/error/mod.rs b/dhall/src/error/mod.rs
index 02e8ed3..4d59cbb 100644
--- a/dhall/src/error/mod.rs
+++ b/dhall/src/error/mod.rs
@@ -104,16 +104,16 @@ impl std::fmt::Display for TypeError {
         use TypeMessage::*;
         let msg = match &self.message {
             UnboundVariable(span) => span.error("Type error: Unbound variable"),
-            InvalidInputType(_) => {
-                "Type error: Invalid function input".to_string()
+            InvalidInputType(v) => {
+                v.span().error("Type error: Invalid function input")
             }
-            InvalidOutputType(_) => {
-                "Type error: Invalid function output".to_string()
-            }
-            NotAFunction(_) => "Type error: Not a function".to_string(),
-            TypeMismatch(_, _, _) => {
-                "Type error: Wrong type of function argument".to_string()
+            InvalidOutputType(v) => {
+                v.span().error("Type error: Invalid function output")
             }
+            NotAFunction(v) => v.span().error("Type error: Not a function"),
+            TypeMismatch(v, _, _) => v
+                .span()
+                .error("Type error: Wrong type of function argument"),
             _ => "Type error: Unhandled error".to_string(),
         };
         write!(f, "{}", msg)
diff --git a/dhall/tests/type-errors/hurkensParadox.txt b/dhall/tests/type-errors/hurkensParadox.txt
index ab75f15..69428b8 100644
--- a/dhall/tests/type-errors/hurkensParadox.txt
+++ b/dhall/tests/type-errors/hurkensParadox.txt
@@ -1 +1 @@
-Type error: Wrong type of function argument
+[unknown location] Type error: Wrong type of function argument
diff --git a/dhall/tests/type-errors/unit/FunctionApplicationArgumentNotMatch.txt b/dhall/tests/type-errors/unit/FunctionApplicationArgumentNotMatch.txt
index ab75f15..69428b8 100644
--- a/dhall/tests/type-errors/unit/FunctionApplicationArgumentNotMatch.txt
+++ b/dhall/tests/type-errors/unit/FunctionApplicationArgumentNotMatch.txt
@@ -1 +1 @@
-Type error: Wrong type of function argument
+[unknown location] Type error: Wrong type of function argument
diff --git a/dhall/tests/type-errors/unit/FunctionApplicationIsNotFunction.txt b/dhall/tests/type-errors/unit/FunctionApplicationIsNotFunction.txt
index 4757d2d..062f9de 100644
--- a/dhall/tests/type-errors/unit/FunctionApplicationIsNotFunction.txt
+++ b/dhall/tests/type-errors/unit/FunctionApplicationIsNotFunction.txt
@@ -1 +1,6 @@
-Type error: Not a function
+ --> 1:1
+  |
+1 | True True␊
+  | ^--^
+  |
+  = Type error: Not a function
diff --git a/dhall/tests/type-errors/unit/FunctionArgumentTypeNotAType.txt b/dhall/tests/type-errors/unit/FunctionArgumentTypeNotAType.txt
index faea460..9e43c33 100644
--- a/dhall/tests/type-errors/unit/FunctionArgumentTypeNotAType.txt
+++ b/dhall/tests/type-errors/unit/FunctionArgumentTypeNotAType.txt
@@ -1 +1,6 @@
-Type error: Invalid function input
+ --> 1:7
+  |
+1 | λ(_ : 1) → _␊
+  |       ^
+  |
+  = Type error: Invalid function input
diff --git a/dhall/tests/type-errors/unit/FunctionTypeArgumentTypeNotAType.txt b/dhall/tests/type-errors/unit/FunctionTypeArgumentTypeNotAType.txt
index faea460..dd2e758 100644
--- a/dhall/tests/type-errors/unit/FunctionTypeArgumentTypeNotAType.txt
+++ b/dhall/tests/type-errors/unit/FunctionTypeArgumentTypeNotAType.txt
@@ -1 +1,6 @@
-Type error: Invalid function input
+ --> 1:1
+  |
+1 | 2 → _␊
+  | ^
+  |
+  = Type error: Invalid function input
diff --git a/dhall/tests/type-errors/unit/ListLiteralEmptyNotType.txt b/dhall/tests/type-errors/unit/ListLiteralEmptyNotType.txt
index ab75f15..bc5cc40 100644
--- a/dhall/tests/type-errors/unit/ListLiteralEmptyNotType.txt
+++ b/dhall/tests/type-errors/unit/ListLiteralEmptyNotType.txt
@@ -1 +1,6 @@
-Type error: Wrong type of function argument
+ --> 1:6
+  |
+1 | [] : List Type␊
+  |      ^--^
+  |
+  = Type error: Wrong type of function argument
diff --git a/dhall/tests/type-errors/unit/MergeHandlerNotFunction.txt b/dhall/tests/type-errors/unit/MergeHandlerNotFunction.txt
index 4757d2d..c5ed223 100644
--- a/dhall/tests/type-errors/unit/MergeHandlerNotFunction.txt
+++ b/dhall/tests/type-errors/unit/MergeHandlerNotFunction.txt
@@ -1 +1 @@
-Type error: Not a function
+[unknown location] Type error: Not a function
diff --git a/dhall/tests/type-errors/unit/MergeHandlerNotMatchAlternativeType.txt b/dhall/tests/type-errors/unit/MergeHandlerNotMatchAlternativeType.txt
index ab75f15..69428b8 100644
--- a/dhall/tests/type-errors/unit/MergeHandlerNotMatchAlternativeType.txt
+++ b/dhall/tests/type-errors/unit/MergeHandlerNotMatchAlternativeType.txt
@@ -1 +1 @@
-Type error: Wrong type of function argument
+[unknown location] Type error: Wrong type of function argument
diff --git a/dhall/tests/type-errors/unit/NaturalSubtractNotNatural.txt b/dhall/tests/type-errors/unit/NaturalSubtractNotNatural.txt
index ab75f15..fd906bf 100644
--- a/dhall/tests/type-errors/unit/NaturalSubtractNotNatural.txt
+++ b/dhall/tests/type-errors/unit/NaturalSubtractNotNatural.txt
@@ -1 +1,6 @@
-Type error: Wrong type of function argument
+ --> 1:1
+  |
+1 | Natural/subtract True True␊
+  | ^--------------^
+  |
+  = Type error: Wrong type of function argument
diff --git a/dhall_syntax/src/core/span.rs b/dhall_syntax/src/core/span.rs
index 4012cfb..d63a619 100644
--- a/dhall_syntax/src/core/span.rs
+++ b/dhall_syntax/src/core/span.rs
@@ -69,7 +69,7 @@ impl Span {
         let message: String = message.into();
         let span = match self {
             self::Span::Parsed(span) => span,
-            _ => return format!("Unknown location: {}", message),
+            _ => return format!("[unknown location] {}", message),
         };
         let span = Span::new(&*span.input, span.start, span.end).unwrap();
         let err: ErrorVariant<!> = ErrorVariant::CustomError { message };