1 files changed, 59 insertions, 0 deletions
diff --git a/users/wpcarro/website/sandbox/learnpianochords/src/Misc.elm b/users/wpcarro/website/sandbox/learnpianochords/src/Misc.elm
new file mode 100644
index 0000000000..288d7a825f
--- /dev/null
+++ b/users/wpcarro/website/sandbox/learnpianochords/src/Misc.elm
@@ -0,0 +1,59 @@
+module Misc exposing (..)
+
+import Array exposing (Array)
+
+
+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
+                comesBefore x (z :: rest)
+
+
+find : (a -> Bool) -> List a -> Maybe a
+find pred xs =
+    case xs |> List.filter pred of
+        [] ->
+            Nothing
+
+        x :: _ ->
+            Just x
+
+
+{-| Return the number of milliseconds that elapse during an interval in a
+`target` bpm.
+-}
+bpmToMilliseconds : Int -> Int
+bpmToMilliseconds target =
+    let
+        msPerMinute =
+            1000 * 60
+    in
+    round (toFloat msPerMinute / toFloat target)