Support Misc module

Define two functions for attempting to return an element in a list that precedes
or succeeds another element.

I prefer having something like Utils.List. Perhaps I will refactor.

1 files changed, 15 insertions, 0 deletions

diff --git a/website/sandbox/chord-drill-sergeant/src/Misc.elm b/website/sandbox/chord-drill-sergeant/src/Misc.elm
new file mode 100644
index 000000000000..479234ff1546
--- /dev/null
+++ b/website/sandbox/chord-drill-sergeant/src/Misc.elm
@@ -0,0 +1,15 @@
+module Misc exposing (..)
+
+comesAfter : a -> List a -> Maybe a
+comesAfter x xs =
+    case xs of
+        []         -> Nothing
+        _::[]      -> Nothing
+        y::z::rest -> if y == x then Just z else comesAfter x (z::rest)
+
+comesBefore : a -> List a -> Maybe a
+comesBefore x xs =
+    case xs of
+        []         -> Nothing
+        _::[]      -> Nothing
+        y::z::rest -> if z == x then Just y else comesAfter x (z::rest)