From 4de2ba2590490f38fbfba6515edad6c1b0072042 Mon Sep 17 00:00:00 2001
From: Bob Whitelock <bob.whitelock1@gmail.com>
Date: Tue, 14 Nov 2017 22:13:24 +0000
Subject: [PATCH 1/3] Let latest elm-format do its thing

---
 src/SelectList.elm | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/SelectList.elm b/src/SelectList.elm
index 8eada0e..9aa581c 100644
--- a/src/SelectList.elm
+++ b/src/SelectList.elm
@@ -1,18 +1,18 @@
 module SelectList
     exposing
-        ( SelectList
+        ( Position(..)
+        , SelectList
+        , after
+        , append
+        , before
+        , fromLists
         , map
         , mapBy
-        , Position(..)
-        , fromLists
-        , select
         , prepend
-        , append
-        , before
-        , after
+        , select
         , selected
-        , toList
         , singleton
+        , toList
         )
 
 {-| A `SelectList` is a nonempty list which always has exactly one element selected.
@@ -217,7 +217,7 @@ selectHelp isSelectable beforeList selectedElem afterList =
 
         ( first :: rest, _ ) ->
             if isSelectable first then
-                Just ( [], first, (rest ++ selectedElem :: afterList) )
+                Just ( [], first, rest ++ selectedElem :: afterList )
             else
                 case selectHelp isSelectable rest selectedElem afterList of
                     Nothing ->

From af0cf89504908ac1c147bf791f328f9da6edb716 Mon Sep 17 00:00:00 2001
From: Bob Whitelock <bob.whitelock1@gmail.com>
Date: Tue, 14 Nov 2017 22:28:21 +0000
Subject: [PATCH 2/3] Add `fromList`

---
 src/SelectList.elm | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/SelectList.elm b/src/SelectList.elm
index 9aa581c..f24fa0f 100644
--- a/src/SelectList.elm
+++ b/src/SelectList.elm
@@ -5,6 +5,7 @@ module SelectList
         , after
         , append
         , before
+        , fromList
         , fromLists
         , map
         , mapBy
@@ -19,7 +20,7 @@ module SelectList
 
 It is an example of a list [zipper](https://en.wikipedia.org/wiki/Zipper_(data_structure)).
 
-@docs SelectList, fromLists, singleton
+@docs SelectList, fromLists, fromList, singleton
 
 
 ## Reading
@@ -171,6 +172,22 @@ fromLists =
     SelectList
 
 
+{-| -}
+fromList : List a -> Maybe (SelectList a)
+fromList list =
+    let
+        ( maybeHead, maybeTail ) =
+            ( List.head list, List.tail list )
+    in
+    Maybe.map2
+        (\head ->
+            \tail ->
+                fromLists [] head tail
+        )
+        maybeHead
+        maybeTail
+
+
 {-| Change the selected element to the first one which passes a
 predicate function. If no elements pass, the `SelectList` is unchanged.
 

From bdd803aa53fdbe542068e64a0de07ca5dd479832 Mon Sep 17 00:00:00 2001
From: Bob Whitelock <bob.whitelock1@gmail.com>
Date: Tue, 14 Nov 2017 22:33:09 +0000
Subject: [PATCH 3/3] Add `decoder`

---
 src/SelectList.elm | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/SelectList.elm b/src/SelectList.elm
index f24fa0f..b022867 100644
--- a/src/SelectList.elm
+++ b/src/SelectList.elm
@@ -5,6 +5,7 @@ module SelectList
         , after
         , append
         , before
+        , decoder
         , fromList
         , fromLists
         , map
@@ -32,8 +33,15 @@ It is an example of a list [zipper](https://en.wikipedia.org/wiki/Zipper_(data_s
 
 @docs map, mapBy, Position, select, append, prepend
 
+
+## Decoding
+
+@docs decoder
+
 -}
 
+import Json.Decode
+
 
 {-| A nonempty list which always has exactly one element selected.
 
@@ -287,3 +295,20 @@ prepend list (SelectList beforeSel sel afterSel) =
 toList : SelectList a -> List a
 toList (SelectList beforeSel sel afterSel) =
     beforeSel ++ sel :: afterSel
+
+
+{-| -}
+decoder : Json.Decode.Decoder a -> Json.Decode.Decoder (SelectList a)
+decoder itemDecoder =
+    let
+        createSelectList =
+            \list ->
+                case fromList list of
+                    Just selectList ->
+                        Json.Decode.succeed selectList
+
+                    Nothing ->
+                        Json.Decode.fail "expected list with more than one element"
+    in
+    Json.Decode.list itemDecoder
+        |> Json.Decode.andThen createSelectList