diff --git a/chorale.cabal b/chorale.cabal
--- a/chorale.cabal
+++ b/chorale.cabal
@@ -1,5 +1,5 @@
 name:           chorale
-version:        0.1.2
+version:        0.1.3
 homepage:       https://github.com/mocnik-science/chorale
 bug-reports:    https://github.com/mocnik-science/chorale/issues
 synopsis:       A module containing basic functions that the prelude does not offer
diff --git a/src/Chorale/Common.hs b/src/Chorale/Common.hs
--- a/src/Chorale/Common.hs
+++ b/src/Chorale/Common.hs
@@ -114,6 +114,7 @@
     sortAndGroup,
     sortAndGroupBy,
     sortAndGroupLookupBy,
+    lookupBy,
     -- * List Operations
     notNull,
     takeWhileList,
@@ -580,6 +581,12 @@
 -- | sort and than group to a lookup table
 sortAndGroupLookupBy :: Ord b => (a -> b) -> [a] -> [(b, [a])]
 sortAndGroupLookupBy f = map (map21 (f . head, id)) . sortAndGroupBy f
+
+-- | lookup by using a function
+--
+-- @lookupBy f b xs@ finds the element @x@ which satisfies @f x = b@
+lookupBy :: Eq b => (a -> b) -> b -> [a] -> Maybe a
+lookupBy f b = lookup b . map (map21 (f, id))
 
 -- --== LIST OPERATIONS