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diff --git a/dhall/src/errors/InvalidOptionalLiteral.txt b/dhall/src/errors/InvalidOptionalLiteral.txt
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+Explanation: The syntax for ❰Optional❱ values resembles the syntax for ❰List❱s:
+
+
+    ┌───────────────────────┐
+    │ [] : Optional Integer │  An ❰Optional❱ value which is absent
+    └───────────────────────┘
+
+
+    ┌───────────────────────┐
+    │ [] : List     Integer │  An empty (0-element) ❰List❱
+    └───────────────────────┘
+
+
+    ┌────────────────────────┐
+    │ [1] : Optional Integer │  An ❰Optional❱ value which is present
+    └────────────────────────┘
+
+
+    ┌────────────────────────┐
+    │ [1] : List     Integer │  A singleton (1-element) ❰List❱
+    └────────────────────────┘
+
+
+However, an ❰Optional❱ value can $_NOT have more than one element, whereas a
+❰List❱ can have multiple elements:
+
+
+    ┌───────────────────────────┐
+    │ [1, 2] : Optional Integer │  Invalid: multiple elements $_NOT allowed
+    └───────────────────────────┘
+
+
+    ┌───────────────────────────┐
+    │ [1, 2] : List     Integer │  Valid: multiple elements allowed
+    └───────────────────────────┘
+
+
+Your ❰Optional❱ value had this many elements:
+
+↳ $txt0
+
+... when an ❰Optional❱ value can only have at most one element
+
+Some common reasons why you might get this error:
+
+● You accidentally typed ❰Optional❱ when you meant ❰List❱, like this:
+
+
+    ┌────────────────────────────────────────────────────┐
+    │ List/length Integer ([1, 2, 3] : Optional Integer) │
+    └────────────────────────────────────────────────────┘
+                                       ⇧
+                                       This should be ❰List❱ instead