Using incomes to compute a fair computation to designate the payer

3 files changed, 36 insertions, 1 deletions

diff --git a/src/client/Utils/Dict.elm b/src/client/Utils/Dict.elm
new file mode 100644
index 0000000..dc01b17
--- /dev/null
+++ b/src/client/Utils/Dict.elm
@@ -0,0 +1,11 @@
+module Utils.Dict
+  ( mapValues
+  ) where
+
+import Dict as Dict exposing (..)
+
+mapValues : (a -> b) -> Dict comparable a -> Dict comparable b
+mapValues f = Dict.fromList << List.map (onSecond f) << Dict.toList
+
+onSecond : (a -> b) -> (comparable, a) -> (comparable, b)
+onSecond f tuple = case tuple of (x, y) -> (x, f y)
diff --git a/src/client/Utils/List.elm b/src/client/Utils/List.elm
new file mode 100644
index 0000000..f33e124
--- /dev/null
+++ b/src/client/Utils/List.elm
@@ -0,0 +1,6 @@
+module Utils.List
+  ( find
+  ) where
+
+find : (a -> Bool) -> List a -> Maybe a
+find predicate = List.head << List.filter predicate
diff --git a/src/client/Utils/Maybe.elm b/src/client/Utils/Maybe.elm
index 507d9a4..d954ae0 100644
--- a/src/client/Utils/Maybe.elm
+++ b/src/client/Utils/Maybe.elm
@@ -1,9 +1,27 @@
 module Utils.Maybe
   ( isJust
+  , catMaybes
+  , maybeToList
   ) where
 
 isJust : Maybe a -> Bool
 isJust maybe =
   case maybe of
-    Just _ -> True
+    Just _  -> True
     Nothing -> False
+
+catMaybes : List (Maybe a) -> List a
+catMaybes =
+  List.foldr
+    (\mb xs ->
+      case mb of
+        Just x  -> x :: xs
+        Nothing -> xs
+    )
+    []
+
+maybeToList : Maybe a -> List a
+maybeToList mb =
+  case mb of
+    Just a  -> [a]
+    Nothing -> []