Add constructor helpers for letter keys

Author: hojberg

src/UI/KeyboardShortcut/Key.elm

@@ -21,7 +21,10 @@ module UI.KeyboardShortcut.Key exposing
     , decode
     , fromString
     , isModifier
+    , letter
+    , lower
     , toNumber
+    , upper
     , view
     )
 
@@ -113,6 +116,21 @@ type Key
     | Raw String
 
 
+letter : (LetterCase -> Key) -> Key
+letter k =
+    k Lower
+
+
+lower : (LetterCase -> Key) -> Key
+lower k =
+    letter k
+
+
+upper : (LetterCase -> Key) -> Key
+upper k =
+    k Upper
+
+
 
 -- HELPERS