diff --git a/language-elm.cabal b/language-elm.cabal
--- a/language-elm.cabal
+++ b/language-elm.cabal
@@ -1,42 +1,70 @@
-name:               language-elm
-version:            0.1.0.3
-synopsis:           Generate elm code
-description:        Generate elm code from an ast
-homepage:           https://github.com/eliaslfox/language-elm#readme
-license:            BSD3
-license-file:       LICENSE
-author:             Elias Lawson-Fox
-maintainer:         eliaslfox@gmail.com
-copyright:          2017 Elias Lawson-Fox
-category:           Web
-build-type:         Simple
-extra-source-files: README.md
-cabal-version:      >=1.10
+-- This file has been generated from package.yaml by hpack version 0.28.2.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: 051b4a8042d05f18fb64b3714184c09ca9363d68b341ec9be6effdb370eeabe0
 
+name:           language-elm
+version:        0.1.1.0
+synopsis:       Generate elm code
+description:    Generate elm code from an ast
+category:       Web
+homepage:       https://github.com/eliaslfox/language-elm#readme
+bug-reports:    https://github.com/eliaslfox/language-elm/issues
+author:         Elias Lawson-Fox
+maintainer:     eliaslfox@gmail.com
+copyright:      2017 Elias Lawson-Fox
+license:        BSD3
+license-file:   LICENSE
+build-type:     Simple
+cabal-version:  >= 1.10
+extra-source-files:
+    README.md
+
+source-repository head
+  type: git
+  location: https://github.com/eliaslfox/language-elm
+
 library
-  hs-source-dirs:   src
-  exposed-modules:  Elm, Elm.Decleration, Elm.Expression, Elm.Import, Elm.Program, Elm.Type, Elm.Classes, Elm.GenError
-  build-depends:    base >= 4.9.1 && < 4.10, 
-                       pretty >= 1.1.3 && < 1.2,
-                       MissingH >= 1.4.0 && < 1.5,
-                       mtl >= 2.2.1 && < 2.3,
-                       protolude >= 0.1.1 && < 0.2
+  exposed-modules:
+      Elm
+      Elm.Decleration
+      Elm.Expression
+      Elm.Import
+      Elm.Program
+      Elm.Type
+      Elm.Classes
+      Elm.GenError
+  other-modules:
+      Paths_language_elm
+  hs-source-dirs:
+      src
+  build-depends:
+      MissingH
+    , base >=4.11 && <=4.12
+    , mtl
+    , pretty
+    , protolude
+  build-tools:
+      doctest
   default-language: Haskell2010
 
 test-suite language-elm-test
-  type:             exitcode-stdio-1.0
-  hs-source-dirs:   test
-  main-is:          Spec.hs
-  other-modules:    Renderer
-  build-depends:    base
-                     , language-elm
-                     , pretty >= 1.1.3 && < 1.2
-                     , hspec >= 2.4.3 && < 2.5
-                     , mtl >= 2.2.1 && < 2.3
-                     , protolude >= 0.1.1 && < 0.2
-  ghc-options:      -threaded -rtsopts -with-rtsopts=-N
+  type: exitcode-stdio-1.0
+  main-is: Spec.hs
+  other-modules:
+      Renderer
+      Paths_language_elm
+  hs-source-dirs:
+      test
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      base >=4.11 && <=4.12
+    , hspec
+    , language-elm
+    , mtl
+    , pretty
+    , protolude
+  build-tools:
+      doctest
   default-language: Haskell2010
-
-source-repository head
-  type:             git
-  location:         https://github.com/eliaslfox/language-elm
diff --git a/src/Elm.hs b/src/Elm.hs
--- a/src/Elm.hs
+++ b/src/Elm.hs
@@ -68,6 +68,7 @@
 import qualified Elm.Program
 import qualified Elm.Type             (TypeDec (..))
 import qualified Text.PrettyPrint
+import Prelude (error)
 
 type Expr = Elm.Expression.Expr
 type Type = Elm.Type.TypeDec
diff --git a/src/Elm/Expression.hs b/src/Elm/Expression.hs
--- a/src/Elm/Expression.hs
+++ b/src/Elm/Expression.hs
@@ -13,7 +13,6 @@
 
 import           Control.Monad        (mapM, when)
 import           Control.Monad.Writer (tell)
-import           Data.List            hiding (map)
 import           Data.String          (IsString (..), String)
 import           Elm.Classes          (Generate (..))
 import           Elm.GenError         (GenError (..))
diff --git a/src/Elm/GenError.hs b/src/Elm/GenError.hs
--- a/src/Elm/GenError.hs
+++ b/src/Elm/GenError.hs
@@ -15,8 +15,10 @@
     | Error String
     deriving (Eq, Show)
 
+instance Semigroup GenError where
+  (Error x) <> _ = Error x
+  _ <> (Error y) = Error y
+  (WarningList x) <> (WarningList y) = WarningList $ x <> y
+
 instance Monoid GenError where
-    mappend (Error str) _                   = Error str
-    mappend _ (Error str)                   = Error str
-    mappend (WarningList a) (WarningList b) = WarningList $ a ++ b
     mempty = WarningList []