diff --git a/Statistics/Distribution/Normal.hs b/Statistics/Distribution/Normal.hs
--- a/Statistics/Distribution/Normal.hs
+++ b/Statistics/Distribution/Normal.hs
@@ -23,7 +23,7 @@
 import Control.Exception (assert)
 import Data.Number.Erf (erfc)
 import Data.Typeable (Typeable)
-import Statistics.Constants (m_huge, m_sqrt_2, m_sqrt_2_pi)
+import Statistics.Constants (m_sqrt_2, m_sqrt_2_pi)
 import qualified Statistics.Distribution as D
 import qualified Statistics.Sample as S
 
@@ -76,8 +76,10 @@
 
 quantile :: NormalDistribution -> Double -> Double
 quantile d p
-  | p == 0    = -m_huge
-  | p == 1    = m_huge
-  | p == 0.5  = mean d
-  | otherwise = x * sqrt (variance d) + mean d
-  where x     = D.findRoot standard p 0 (-100) 100
+  | p < 0 || p > 1 = inf/inf
+  | p == 0         = -inf
+  | p == 1         = inf
+  | p == 0.5       = mean d
+  | otherwise      = x * sqrt (variance d) + mean d
+  where x          = D.findRoot standard p 0 (-100) 100
+        inf        = 1/0
diff --git a/Statistics/Function.hs b/Statistics/Function.hs
--- a/Statistics/Function.hs
+++ b/Statistics/Function.hs
@@ -15,11 +15,13 @@
       minMax
     , sort
     , partialSort
+    -- * Array setup
     , createU
+    , createIO
     ) where
 
 import Control.Exception (assert)
-import Control.Monad.ST (ST)
+import Control.Monad.ST (ST, unsafeIOToST, unsafeSTToIO)
 import Data.Array.Vector.Algorithms.Combinators (apply)
 import Data.Array.Vector
 import qualified Data.Array.Vector.Algorithms.Intro as I
@@ -48,7 +50,8 @@
     fini (MM lo hi) = lo :*: hi
 {-# INLINE minMax #-}
 
--- | Create an array, using the given action to populate each element.
+-- | Create an array, using the given 'ST' action to populate each
+-- element.
 createU :: (UA e) => forall s. Int -> (Int -> ST s e) -> ST s (UArr e)
 createU size itemAt = assert (size >= 0) $
     newMU size >>= loop 0
@@ -58,3 +61,11 @@
       r <- itemAt k
       writeMU arr k r
       loop (k+1) arr
+{-# INLINE createU #-}
+
+-- | Create an array, using the given 'IO' action to populate each
+-- element.
+createIO :: (UA e) => Int -> (Int -> IO e) -> IO (UArr e)
+createIO size itemAt =
+    unsafeSTToIO $ createU size (unsafeIOToST . itemAt)
+{-# INLINE createIO #-}
diff --git a/statistics.cabal b/statistics.cabal
--- a/statistics.cabal
+++ b/statistics.cabal
@@ -1,5 +1,5 @@
 name:           statistics
-version:        0.3.1
+version:        0.3.2
 synopsis:       A library of statistical types, data, and functions
 description:
   This library provides a number of common functions and types useful