diff --git a/hydrogen-prelude.cabal b/hydrogen-prelude.cabal
--- a/hydrogen-prelude.cabal
+++ b/hydrogen-prelude.cabal
@@ -1,5 +1,5 @@
 name:                 hydrogen-prelude
-version:              0.1.0.1
+version:              0.1.1
 homepage:             https://github.com/scravy/hydrogen-prelude
 synopsis:             Hydrogen Prelude
 license:              BSD3
diff --git a/src/Hydrogen/Prelude.hs b/src/Hydrogen/Prelude.hs
--- a/src/Hydrogen/Prelude.hs
+++ b/src/Hydrogen/Prelude.hs
@@ -19,8 +19,11 @@
   , module Data.Time
   , module Data.Tuple
   , module Data.Word
+  , module Numeric
   , module Text.Printf
   , (.&), (.|), (=~), (=~~)
+  , for
+  , Map, Set
   ) where
 
 import "base" Prelude hiding (
@@ -91,11 +94,18 @@
 import "base" Data.Tuple
 import "base" Data.Word
 
+import "base" Numeric
+
 import "base" Text.Printf
 import "regex-tdfa" Text.Regex.TDFA
 
+import "containers" Data.Map (Map)
+import "containers" Data.Set (Set)
+
 (.|), (.&) :: (a -> Bool) -> (a -> Bool) -> (a -> Bool)
 f .| g = \x -> f x || g x
 f .& g = \x -> f x && g x
 
+for :: [a] -> (a -> b) -> [b]
+for = flip map