diff --git a/CHANGES.markdown b/CHANGES.markdown
--- a/CHANGES.markdown
+++ b/CHANGES.markdown
@@ -1,3 +1,9 @@
+1.4.2 (4 Feb 2018)
+------------------
+
+- New function `Diagrams.TwoD.Layout.Constrained.runLayout` (thanks to
+  Sandy Maguire)
+
 1.4.1 (3 July 2017)
 ---------------------
 
@@ -5,6 +11,10 @@
 - allow base-4.10 (for GHC-8.2)
 - allow MonadRandom-0.5
 - export some things inadvertently unexported from Diagrams.TwoD.Grid (#68)
+
+Hackage revisions:
+- r1:
+    - allow `QuickCheck-2.11`
 
 1.4.0.1 (13 November 2016)
 --------------------------
diff --git a/diagrams-contrib.cabal b/diagrams-contrib.cabal
--- a/diagrams-contrib.cabal
+++ b/diagrams-contrib.cabal
@@ -1,5 +1,5 @@
 name:                diagrams-contrib
-version:             1.4.1
+version:             1.4.2
 synopsis:            Collection of user contributions to diagrams EDSL
 description:         A collection of user contributions for diagrams,
                      an embedded domain-specific language for generation
@@ -12,7 +12,7 @@
 Bug-reports:         http://github.com/diagrams/diagrams-contrib/issues
 category:            Graphics
 build-type:          Simple
-cabal-version:       >=1.10
+cabal-version:       >=1.18
 extra-source-files:  README.markdown, CHANGES.markdown, diagrams/*.svg, CONTRIBUTORS
 extra-doc-files:     diagrams/*.svg
 tested-with:         GHC == 7.8.4, GHC == 7.10.2, GHC == 8.0.1, GHC == 8.2.1
@@ -87,7 +87,7 @@
   other-modules:       Diagrams.TwoD.Path.Turtle.Tests
 
   build-depends:       HUnit                      >= 1.2 && < 1.7,
-                       QuickCheck                 >= 2.4 && < 2.11,
+                       QuickCheck                 >= 2.4 && < 2.12,
                        containers                 >= 0.3 && < 0.6,
                        test-framework             >= 0.4 && < 0.9,
                        test-framework-hunit       >= 0.2 && < 0.4,
diff --git a/src/Diagrams/TwoD/Layout/Constrained.hs b/src/Diagrams/TwoD/Layout/Constrained.hs
--- a/src/Diagrams/TwoD/Layout/Constrained.hs
+++ b/src/Diagrams/TwoD/Layout/Constrained.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE Rank2Types       #-}
 {-# LANGUAGE TemplateHaskell  #-}
+{-# LANGUAGE TupleSections    #-}
 {-# LANGUAGE ViewPatterns     #-}
 
 -----------------------------------------------------------------------------
@@ -109,6 +110,7 @@
 
          -- * Layout
        , layout
+       , runLayout
 
          -- * Creating constrainable things
 
@@ -620,12 +622,20 @@
   :: (Monoid' m, Hashable n, Floating n, RealFrac n, Show n)
   => (forall s. Constrained s b n m a)
   -> QDiagram b V2 n m
-layout constr =
+layout constr = snd $ runLayout constr
+
+-- | Like 'layout', but also allows the caller to retrieve the result of the
+--   'Constrained' computation.
+runLayout
+  :: (Monoid' m, Hashable n, Floating n, RealFrac n, Show n)
+  => (forall s. Constrained s b n m a)
+  -> (a, QDiagram b V2 n m)
+runLayout constr =
   case MFS.execSolver (MFS.ignore $ s ^. equations) MFS.noDeps of
     Left _depError -> error "overconstrained"
     Right deps    ->
       let deps' = resolve (map fst dias) deps
-      in  mconcat . flip map dias $ \(d, dia) ->
+      in  (a, ) . mconcat . flip map dias $ \(d, dia) ->
         let vars = getDiaVars deps' d
             expectedRes ty = vars ^?! L.at ty . _Just . resolution . _Just
         in
@@ -641,7 +651,7 @@
                  -- a diagram if they aren't already constrained, so getDiaVars
                  -- should return three resolved variables
   where
-    s = execState constr initConstrainedState
+    (a, s) = runState constr initConstrainedState
     dias = M.assocs (s ^. diagrams)
 
 resolve
diff --git a/src/Diagrams/TwoD/Path/Follow.hs b/src/Diagrams/TwoD/Path/Follow.hs
--- a/src/Diagrams/TwoD/Path/Follow.hs
+++ b/src/Diagrams/TwoD/Path/Follow.hs
@@ -61,7 +61,7 @@
 --
 newtype Following n
   = Following { unFollowing :: Semi (Trail' Line V2 n) (Angle n) }
-  deriving (Monoid)
+  deriving (Monoid, Semigroup)
 
 -- | Note this is only an iso when considering trails equivalent up to
 --   rotation.