Upgrade map to traverse

1 files changed, 16 insertions, 6 deletions

diff --git a/dhall_core/src/text.rs b/dhall_core/src/text.rs
index 9500f32..7c0e2b4 100644
--- a/dhall_core/src/text.rs
+++ b/dhall_core/src/text.rs
@@ -34,18 +34,28 @@ pub enum InterpolatedTextContents<SubExpr> {
 }
 
 impl<SubExpr> InterpolatedText<SubExpr> {
-    pub fn map<SubExpr2, F>(self, mut f: F) -> InterpolatedText<SubExpr2>
+    pub fn traverse<SubExpr2, E, F>(
+        self,
+        mut f: F,
+    ) -> Result<InterpolatedText<SubExpr2>, E>
     where
-        F: FnMut(SubExpr) -> SubExpr2,
+        F: FnMut(SubExpr) -> Result<SubExpr2, E>,
     {
-        InterpolatedText {
+        Ok(InterpolatedText {
             head: self.head.clone(),
             tail: self
                 .tail
                 .into_iter()
-                .map(|(e, s)| (f(e), s.clone()))
-                .collect(),
-        }
+                .map(|(e, s)| Ok((f(e)?, s.clone())))
+                .collect::<Result<_, _>>()?,
+        })
+    }
+
+    pub fn map<SubExpr2, F>(self, mut f: F) -> InterpolatedText<SubExpr2>
+    where
+        F: FnMut(SubExpr) -> SubExpr2,
+    {
+        crate::trivial_result(self.traverse(|e| Ok(f(e))))
     }
 
     pub fn as_ref(&self) -> InterpolatedText<&SubExpr> {