diff --git a/Text/PrettyPrint/Mainland.hs b/Text/PrettyPrint/Mainland.hs
--- a/Text/PrettyPrint/Mainland.hs
+++ b/Text/PrettyPrint/Mainland.hs
@@ -42,7 +42,7 @@
     empty,
     srcloc, line, softline, softbreak,
     (<>), (<|>), (<+>), (</>), (<+/>), (<//>),
-    group,
+    group, flatten,
 
     -- ** Wrapping documents in delimiters
     enclose, squotes, dquotes, angles, backquotes, braces, brackets, parens,
@@ -335,6 +335,7 @@
 group :: Doc -> Doc
 group d = flatten d `Alt` d
 
+-- | The document @'flatten' d@ will flatten @d@ to /one/ line.
 flatten :: Doc -> Doc
 flatten Empty        = Empty
 flatten (Char c)     = Char c
@@ -389,6 +390,7 @@
 parensIf :: Bool -> Doc -> Doc
 parensIf True doc  = parens doc
 parensIf False doc = doc
+
 -- | The document @'folddoc' f ds@ obeys the laws:
 --
 -- * @'folddoc' f [] = 'empty'@
diff --git a/mainland-pretty.cabal b/mainland-pretty.cabal
--- a/mainland-pretty.cabal
+++ b/mainland-pretty.cabal
@@ -1,5 +1,5 @@
 name:           mainland-pretty
-version:        0.4.0.0
+version:        0.4.1.0
 cabal-version:  >= 1.6
 license:        BSD3
 license-file:   LICENSE