diff --git a/app/Command/Bundle.hs b/app/Command/Bundle.hs
index 4ea338a241..115c439a36 100644
--- a/app/Command/Bundle.hs
+++ b/app/Command/Bundle.hs
@@ -7,7 +7,6 @@
 module Command.Bundle (command) where
 
 import           Data.Traversable (for)
-import           Data.Monoid ((<>))
 import           Data.Aeson (encode)
 import           Data.Maybe (isNothing)
 import           Control.Applicative
diff --git a/app/Command/Compile.hs b/app/Command/Compile.hs
index cb91b6173a..713524c595 100644
--- a/app/Command/Compile.hs
+++ b/app/Command/Compile.hs
@@ -8,7 +8,6 @@ module Command.Compile (command) where
 
 import           Control.Applicative
 import           Control.Monad
-import           Control.Monad.Writer.Strict
 import qualified Data.Aeson as A
 import           Data.Bool (bool)
 import qualified Data.ByteString.Lazy as B
diff --git a/app/Command/Hierarchy.hs b/app/Command/Hierarchy.hs
index 1bb9346534..0966c9a7b6 100644
--- a/app/Command/Hierarchy.hs
+++ b/app/Command/Hierarchy.hs
@@ -22,7 +22,6 @@ import           Protolude (catMaybes)
 
 import           Control.Applicative (optional)
 import           Data.Foldable (for_)
-import           Data.Monoid ((<>))
 import qualified Data.Text as T
 import qualified Data.Text.IO as T
 import           Options.Applicative (Parser)
diff --git a/app/Command/Publish.hs b/app/Command/Publish.hs
index 0440bae107..bffb3e838a 100644
--- a/app/Command/Publish.hs
+++ b/app/Command/Publish.hs
@@ -5,7 +5,6 @@ module Command.Publish (command) where
 import           Control.Monad.IO.Class (liftIO)
 import qualified Data.Aeson as A
 import qualified Data.ByteString.Lazy.Char8 as BL
-import           Data.Monoid ((<>))
 import           Data.Time.Clock (getCurrentTime)
 import           Data.Version (Version(..))
 import           Language.PureScript.Publish
diff --git a/app/Command/REPL.hs b/app/Command/REPL.hs
index 04033b57eb..1093733c7b 100644
--- a/app/Command/REPL.hs
+++ b/app/Command/REPL.hs
@@ -31,7 +31,6 @@ import           Control.Monad.Trans.State.Strict (StateT, evalStateT)
 import           Control.Monad.Trans.Reader (ReaderT, runReaderT)
 import           Data.FileEmbed (embedStringFile)
 import           Data.Foldable (for_)
-import           Data.Monoid ((<>))
 import           Data.String (IsString(..))
 import           Data.Text (Text, unpack)
 import           Data.Traversable (for)
diff --git a/app/Main.hs b/app/Main.hs
index 1f5ec06ef9..f3e72ab68a 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -15,7 +15,6 @@ import qualified Command.Ide as Ide
 import qualified Command.Publish as Publish
 import qualified Command.REPL as REPL
 import           Data.Foldable (fold)
-import           Data.Monoid ((<>))
 import qualified Options.Applicative as Opts
 import           System.Environment (getArgs)
 import qualified System.IO as IO
diff --git a/appveyor.yml b/appveyor.yml
index d2788c2071..a3fa6b1c51 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -3,9 +3,12 @@ version: '{build}'
 environment:
   # Keep the path as short as possible, just in case.
   STACK_ROOT: c:\s
-  STACK_VER: 1.6.3
+  STACK_VER: 1.7.1
   RELEASE_USER: purescript
   RELEASE_REPO: purescript
+  # See https://github.com/commercialhaskell/stack/issues/3944, might no 
+  # longer be necessary after we've moved to a snapshot with network >= 0.2.7.1
+  TMP: "c:\\tmp"
 branches:
   # Only build master and tagged versions, i.e. not feature branches; feature
   # branches already get built after opening a pull request.
@@ -19,7 +22,7 @@ cache:
 - c:\s -> appveyor/cache-buster.txt
 install:
 - git submodule update --init
-- ps: Install-Product node 6
+- ps: Install-Product node 8
 - npm install -g bower
 
 - ps: |
diff --git a/package.yaml b/package.yaml
index 16f9ed8722..01094bf840 100644
--- a/package.yaml
+++ b/package.yaml
@@ -32,15 +32,16 @@ extra-source-files:
   - CONTRIBUTORS.md
   - CONTRIBUTING.md
 dependencies:
-  - aeson >=1.0 && <1.3
+  - aeson >=1.0 && <1.4
   - aeson-better-errors >=0.8
   - ansi-terminal >=0.7.1 && <0.9
-  - base >=4.8 && <4.11
+  - base >=4.8 && <4.12
   - base-compat >=0.6.0
   - blaze-html >=0.8.1 && <0.10
   - bower-json >=1.0.0.1 && <1.1
   - boxes >=0.1.4 && <0.2.0
   - bytestring
+  - Cabal >= 2.2
   - cheapskate >=0.1 && <0.2
   - clock
   - containers
@@ -70,7 +71,6 @@ dependencies:
   - scientific >=0.3.4.9 && <0.4
   - semigroups >=0.16.2 && <0.19
   - sourcemap >=0.1.6
-  - spdx ==0.2.*
   - split
   - stm >=0.2.4.0
   - stringsearch
diff --git a/src/Language/PureScript/AST/Binders.hs b/src/Language/PureScript/AST/Binders.hs
index 82d23e03b5..19e1d18db8 100644
--- a/src/Language/PureScript/AST/Binders.hs
+++ b/src/Language/PureScript/AST/Binders.hs
@@ -5,8 +5,6 @@ module Language.PureScript.AST.Binders where
 
 import Prelude.Compat
 
-import Data.Semigroup
-
 import Language.PureScript.AST.SourcePos
 import Language.PureScript.AST.Literals
 import Language.PureScript.Names
diff --git a/src/Language/PureScript/AST/SourcePos.hs b/src/Language/PureScript/AST/SourcePos.hs
index 60605d7aaa..6ad67542d7 100644
--- a/src/Language/PureScript/AST/SourcePos.hs
+++ b/src/Language/PureScript/AST/SourcePos.hs
@@ -8,7 +8,6 @@ import Prelude.Compat
 
 import Control.DeepSeq (NFData)
 import Data.Aeson ((.=), (.:))
-import Data.Monoid
 import Data.Text (Text)
 import GHC.Generics (Generic)
 import Language.PureScript.Comments
diff --git a/src/Language/PureScript/AST/Traversals.hs b/src/Language/PureScript/AST/Traversals.hs
index f4a35f5f40..4852488938 100644
--- a/src/Language/PureScript/AST/Traversals.hs
+++ b/src/Language/PureScript/AST/Traversals.hs
@@ -264,66 +264,66 @@ everythingOnValues
      , CaseAlternative -> r
      , DoNotationElement -> r
      )
-everythingOnValues (<>) f g h i j = (f', g', h', i', j')
+everythingOnValues (<>.) f g h i j = (f', g', h', i', j')
   where
 
   f' :: Declaration -> r
-  f' d@(DataBindingGroupDeclaration ds) = foldl (<>) (f d) (fmap f' ds)
-  f' d@(ValueDeclaration vd) = foldl (<>) (f d) (fmap h' (valdeclBinders vd) ++ concatMap (\(GuardedExpr grd v) -> fmap k' grd ++ [g' v]) (valdeclExpression vd))
-  f' d@(BindingGroupDeclaration ds) = foldl (<>) (f d) (fmap (\(_, _, val) -> g' val) ds)
-  f' d@(TypeClassDeclaration _ _ _ _ _ ds) = foldl (<>) (f d) (fmap f' ds)
-  f' d@(TypeInstanceDeclaration _ _ _ _ _ _ _ (ExplicitInstance ds)) = foldl (<>) (f d) (fmap f' ds)
-  f' d@(BoundValueDeclaration _ b expr) = f d <> h' b <> g' expr
+  f' d@(DataBindingGroupDeclaration ds) = foldl (<>.) (f d) (fmap f' ds)
+  f' d@(ValueDeclaration vd) = foldl (<>.) (f d) (fmap h' (valdeclBinders vd) ++ concatMap (\(GuardedExpr grd v) -> fmap k' grd ++ [g' v]) (valdeclExpression vd))
+  f' d@(BindingGroupDeclaration ds) = foldl (<>.) (f d) (fmap (\(_, _, val) -> g' val) ds)
+  f' d@(TypeClassDeclaration _ _ _ _ _ ds) = foldl (<>.) (f d) (fmap f' ds)
+  f' d@(TypeInstanceDeclaration _ _ _ _ _ _ _ (ExplicitInstance ds)) = foldl (<>.) (f d) (fmap f' ds)
+  f' d@(BoundValueDeclaration _ b expr) = f d <>. h' b <>. g' expr
   f' d = f d
 
   g' :: Expr -> r
   g' v@(Literal _ l) = lit (g v) g' l
-  g' v@(UnaryMinus _ v1) = g v <> g' v1
-  g' v@(BinaryNoParens op v1 v2) = g v <> g' op <> g' v1 <> g' v2
-  g' v@(Parens v1) = g v <> g' v1
-  g' v@(TypeClassDictionaryConstructorApp _ v1) = g v <> g' v1
-  g' v@(Accessor _ v1) = g v <> g' v1
-  g' v@(ObjectUpdate obj vs) = foldl (<>) (g v <> g' obj) (fmap (g' . snd) vs)
-  g' v@(ObjectUpdateNested obj vs) = foldl (<>) (g v <> g' obj) (fmap g' vs)
-  g' v@(Abs b v1) = g v <> h' b <> g' v1
-  g' v@(App v1 v2) = g v <> g' v1 <> g' v2
-  g' v@(IfThenElse v1 v2 v3) = g v <> g' v1 <> g' v2 <> g' v3
-  g' v@(Case vs alts) = foldl (<>) (foldl (<>) (g v) (fmap g' vs)) (fmap i' alts)
-  g' v@(TypedValue _ v1 _) = g v <> g' v1
-  g' v@(Let _ ds v1) = foldl (<>) (g v) (fmap f' ds) <> g' v1
-  g' v@(Do es) = foldl (<>) (g v) (fmap j' es)
-  g' v@(Ado es v1) = foldl (<>) (g v) (fmap j' es) <> g' v1
-  g' v@(PositionedValue _ _ v1) = g v <> g' v1
+  g' v@(UnaryMinus _ v1) = g v <>. g' v1
+  g' v@(BinaryNoParens op v1 v2) = g v <>. g' op <>. g' v1 <>. g' v2
+  g' v@(Parens v1) = g v <>. g' v1
+  g' v@(TypeClassDictionaryConstructorApp _ v1) = g v <>. g' v1
+  g' v@(Accessor _ v1) = g v <>. g' v1
+  g' v@(ObjectUpdate obj vs) = foldl (<>.) (g v <>. g' obj) (fmap (g' . snd) vs)
+  g' v@(ObjectUpdateNested obj vs) = foldl (<>.) (g v <>. g' obj) (fmap g' vs)
+  g' v@(Abs b v1) = g v <>. h' b <>. g' v1
+  g' v@(App v1 v2) = g v <>. g' v1 <>. g' v2
+  g' v@(IfThenElse v1 v2 v3) = g v <>. g' v1 <>. g' v2 <>. g' v3
+  g' v@(Case vs alts) = foldl (<>.) (foldl (<>.) (g v) (fmap g' vs)) (fmap i' alts)
+  g' v@(TypedValue _ v1 _) = g v <>. g' v1
+  g' v@(Let _ ds v1) = foldl (<>.) (g v) (fmap f' ds) <>. g' v1
+  g' v@(Do es) = foldl (<>.) (g v) (fmap j' es)
+  g' v@(Ado es v1) = foldl (<>.) (g v) (fmap j' es) <>. g' v1
+  g' v@(PositionedValue _ _ v1) = g v <>. g' v1
   g' v = g v
 
   h' :: Binder -> r
   h' b@(LiteralBinder _ l) = lit (h b) h' l
-  h' b@(ConstructorBinder _ _ bs) = foldl (<>) (h b) (fmap h' bs)
-  h' b@(BinaryNoParensBinder b1 b2 b3) = h b <> h' b1 <> h' b2 <> h' b3
-  h' b@(ParensInBinder b1) = h b <> h' b1
-  h' b@(NamedBinder _ _ b1) = h b <> h' b1
-  h' b@(PositionedBinder _ _ b1) = h b <> h' b1
-  h' b@(TypedBinder _ b1) = h b <> h' b1
+  h' b@(ConstructorBinder _ _ bs) = foldl (<>.) (h b) (fmap h' bs)
+  h' b@(BinaryNoParensBinder b1 b2 b3) = h b <>. h' b1 <>. h' b2 <>. h' b3
+  h' b@(ParensInBinder b1) = h b <>. h' b1
+  h' b@(NamedBinder _ _ b1) = h b <>. h' b1
+  h' b@(PositionedBinder _ _ b1) = h b <>. h' b1
+  h' b@(TypedBinder _ b1) = h b <>. h' b1
   h' b = h b
 
   lit :: r -> (a -> r) -> Literal a -> r
-  lit r go (ArrayLiteral as) = foldl (<>) r (fmap go as)
-  lit r go (ObjectLiteral as) = foldl (<>) r (fmap (go . snd) as)
+  lit r go (ArrayLiteral as) = foldl (<>.) r (fmap go as)
+  lit r go (ObjectLiteral as) = foldl (<>.) r (fmap (go . snd) as)
   lit r _ _ = r
 
   i' :: CaseAlternative -> r
   i' ca@(CaseAlternative bs gs) =
-    foldl (<>) (i ca) (fmap h' bs ++ concatMap (\(GuardedExpr grd val) -> fmap k' grd ++ [g' val]) gs)
+    foldl (<>.) (i ca) (fmap h' bs ++ concatMap (\(GuardedExpr grd val) -> fmap k' grd ++ [g' val]) gs)
 
   j' :: DoNotationElement -> r
-  j' e@(DoNotationValue v) = j e <> g' v
-  j' e@(DoNotationBind b v) = j e <> h' b <> g' v
-  j' e@(DoNotationLet ds) = foldl (<>) (j e) (fmap f' ds)
-  j' e@(PositionedDoNotationElement _ _ e1) = j e <> j' e1
+  j' e@(DoNotationValue v) = j e <>. g' v
+  j' e@(DoNotationBind b v) = j e <>. h' b <>. g' v
+  j' e@(DoNotationLet ds) = foldl (<>.) (j e) (fmap f' ds)
+  j' e@(PositionedDoNotationElement _ _ e1) = j e <>. j' e1
 
   k' :: Guard -> r
   k' (ConditionGuard e) = g' e
-  k' (PatternGuard b e) = h' b <> g' e
+  k' (PatternGuard b e) = h' b <>. g' e
 
 everythingWithContextOnValues
   :: forall s r
@@ -340,50 +340,50 @@ everythingWithContextOnValues
      , Binder            -> r
      , CaseAlternative   -> r
      , DoNotationElement -> r)
-everythingWithContextOnValues s0 r0 (<>) f g h i j = (f'' s0, g'' s0, h'' s0, i'' s0, j'' s0)
+everythingWithContextOnValues s0 r0 (<>.) f g h i j = (f'' s0, g'' s0, h'' s0, i'' s0, j'' s0)
   where
 
   f'' :: s -> Declaration -> r
-  f'' s d = let (s', r) = f s d in r <> f' s' d
+  f'' s d = let (s', r) = f s d in r <>. f' s' d
 
   f' :: s -> Declaration -> r
-  f' s (DataBindingGroupDeclaration ds) = foldl (<>) r0 (fmap (f'' s) ds)
-  f' s (ValueDeclaration vd) = foldl (<>) r0 (fmap (h'' s) (valdeclBinders vd) ++ concatMap (\(GuardedExpr grd v) -> fmap (k' s) grd ++ [g'' s v]) (valdeclExpression vd))
-  f' s (BindingGroupDeclaration ds) = foldl (<>) r0 (fmap (\(_, _, val) -> g'' s val) ds)
-  f' s (TypeClassDeclaration _ _ _ _ _ ds) = foldl (<>) r0 (fmap (f'' s) ds)
-  f' s (TypeInstanceDeclaration _ _ _ _ _ _ _ (ExplicitInstance ds)) = foldl (<>) r0 (fmap (f'' s) ds)
+  f' s (DataBindingGroupDeclaration ds) = foldl (<>.) r0 (fmap (f'' s) ds)
+  f' s (ValueDeclaration vd) = foldl (<>.) r0 (fmap (h'' s) (valdeclBinders vd) ++ concatMap (\(GuardedExpr grd v) -> fmap (k' s) grd ++ [g'' s v]) (valdeclExpression vd))
+  f' s (BindingGroupDeclaration ds) = foldl (<>.) r0 (fmap (\(_, _, val) -> g'' s val) ds)
+  f' s (TypeClassDeclaration _ _ _ _ _ ds) = foldl (<>.) r0 (fmap (f'' s) ds)
+  f' s (TypeInstanceDeclaration _ _ _ _ _ _ _ (ExplicitInstance ds)) = foldl (<>.) r0 (fmap (f'' s) ds)
   f' _ _ = r0
 
   g'' :: s -> Expr -> r
-  g'' s v = let (s', r) = g s v in r <> g' s' v
+  g'' s v = let (s', r) = g s v in r <>. g' s' v
 
   g' :: s -> Expr -> r
   g' s (Literal _ l) = lit g'' s l
   g' s (UnaryMinus _ v1) = g'' s v1
-  g' s (BinaryNoParens op v1 v2) = g'' s op <> g'' s v1 <> g'' s v2
+  g' s (BinaryNoParens op v1 v2) = g'' s op <>. g'' s v1 <>. g'' s v2
   g' s (Parens v1) = g'' s v1
   g' s (TypeClassDictionaryConstructorApp _ v1) = g'' s v1
   g' s (Accessor _ v1) = g'' s v1
-  g' s (ObjectUpdate obj vs) = foldl (<>) (g'' s obj) (fmap (g'' s . snd) vs)
-  g' s (ObjectUpdateNested obj vs) = foldl (<>) (g'' s obj) (fmap (g'' s) vs)
-  g' s (Abs binder v1) = h'' s binder <> g'' s v1
-  g' s (App v1 v2) = g'' s v1 <> g'' s v2
-  g' s (IfThenElse v1 v2 v3) = g'' s v1 <> g'' s v2 <> g'' s v3
-  g' s (Case vs alts) = foldl (<>) (foldl (<>) r0 (fmap (g'' s) vs)) (fmap (i'' s) alts)
+  g' s (ObjectUpdate obj vs) = foldl (<>.) (g'' s obj) (fmap (g'' s . snd) vs)
+  g' s (ObjectUpdateNested obj vs) = foldl (<>.) (g'' s obj) (fmap (g'' s) vs)
+  g' s (Abs binder v1) = h'' s binder <>. g'' s v1
+  g' s (App v1 v2) = g'' s v1 <>. g'' s v2
+  g' s (IfThenElse v1 v2 v3) = g'' s v1 <>. g'' s v2 <>. g'' s v3
+  g' s (Case vs alts) = foldl (<>.) (foldl (<>.) r0 (fmap (g'' s) vs)) (fmap (i'' s) alts)
   g' s (TypedValue _ v1 _) = g'' s v1
-  g' s (Let _ ds v1) = foldl (<>) r0 (fmap (f'' s) ds) <> g'' s v1
-  g' s (Do es) = foldl (<>) r0 (fmap (j'' s) es)
-  g' s (Ado es v1) = foldl (<>) r0 (fmap (j'' s) es) <> g'' s v1
+  g' s (Let _ ds v1) = foldl (<>.) r0 (fmap (f'' s) ds) <>. g'' s v1
+  g' s (Do es) = foldl (<>.) r0 (fmap (j'' s) es)
+  g' s (Ado es v1) = foldl (<>.) r0 (fmap (j'' s) es) <>. g'' s v1
   g' s (PositionedValue _ _ v1) = g'' s v1
   g' _ _ = r0
 
   h'' :: s -> Binder -> r
-  h'' s b = let (s', r) = h s b in r <> h' s' b
+  h'' s b = let (s', r) = h s b in r <>. h' s' b
 
   h' :: s -> Binder -> r
   h' s (LiteralBinder _ l) = lit h'' s l
-  h' s (ConstructorBinder _ _ bs) = foldl (<>) r0 (fmap (h'' s) bs)
-  h' s (BinaryNoParensBinder b1 b2 b3) = h'' s b1 <> h'' s b2 <> h'' s b3
+  h' s (ConstructorBinder _ _ bs) = foldl (<>.) r0 (fmap (h'' s) bs)
+  h' s (BinaryNoParensBinder b1 b2 b3) = h'' s b1 <>. h'' s b2 <>. h'' s b3
   h' s (ParensInBinder b) = h'' s b
   h' s (NamedBinder _ _ b1) = h'' s b1
   h' s (PositionedBinder _ _ b1) = h'' s b1
@@ -391,28 +391,28 @@ everythingWithContextOnValues s0 r0 (<>) f g h i j = (f'' s0, g'' s0, h'' s0, i'
   h' _ _ = r0
 
   lit :: (s -> a -> r) -> s -> Literal a -> r
-  lit go s (ArrayLiteral as) = foldl (<>) r0 (fmap (go s) as)
-  lit go s (ObjectLiteral as) = foldl (<>) r0 (fmap (go s . snd) as)
+  lit go s (ArrayLiteral as) = foldl (<>.) r0 (fmap (go s) as)
+  lit go s (ObjectLiteral as) = foldl (<>.) r0 (fmap (go s . snd) as)
   lit _ _ _ = r0
 
   i'' :: s -> CaseAlternative -> r
-  i'' s ca = let (s', r) = i s ca in r <> i' s' ca
+  i'' s ca = let (s', r) = i s ca in r <>. i' s' ca
 
   i' :: s -> CaseAlternative -> r
-  i' s (CaseAlternative bs gs) = foldl (<>) r0 (fmap (h'' s) bs ++ concatMap (\(GuardedExpr grd val) -> fmap (k' s) grd ++ [g'' s val]) gs)
+  i' s (CaseAlternative bs gs) = foldl (<>.) r0 (fmap (h'' s) bs ++ concatMap (\(GuardedExpr grd val) -> fmap (k' s) grd ++ [g'' s val]) gs)
 
   j'' :: s -> DoNotationElement -> r
-  j'' s e = let (s', r) = j s e in r <> j' s' e
+  j'' s e = let (s', r) = j s e in r <>. j' s' e
 
   j' :: s -> DoNotationElement -> r
   j' s (DoNotationValue v) = g'' s v
-  j' s (DoNotationBind b v) = h'' s b <> g'' s v
-  j' s (DoNotationLet ds) = foldl (<>) r0 (fmap (f'' s) ds)
+  j' s (DoNotationBind b v) = h'' s b <>. g'' s v
+  j' s (DoNotationLet ds) = foldl (<>.) r0 (fmap (f'' s) ds)
   j' s (PositionedDoNotationElement _ _ e1) = j'' s e1
 
   k' :: s -> Guard -> r
   k' s (ConditionGuard e) = g'' s e
-  k' s (PatternGuard b e) = h'' s b <> g'' s e
+  k' s (PatternGuard b e) = h'' s b <>. g'' s e
 
 everywhereWithContextOnValuesM
   :: forall m s
@@ -514,9 +514,6 @@ everythingWithScope
      )
 everythingWithScope f g h i j = (f'', g'', h'', i'', \s -> snd . j'' s)
   where
-  -- Avoid importing Data.Monoid and getting shadowed names above
-  (<>) = mappend
-
   f'' :: S.Set ScopedIdent -> Declaration -> r
   f'' s a = f s a <> f' s a
 
@@ -635,7 +632,7 @@ accumTypes f = everythingOnValues mappend forDecls forValues (const mempty) (con
   forDecls (DataDeclaration _ _ _ _ dctors) = mconcat (concatMap (fmap f . snd) dctors)
   forDecls (ExternDeclaration _ _ ty) = f ty
   forDecls (TypeClassDeclaration _ _ _ implies _ _) = mconcat (concatMap (fmap f . constraintArgs) implies)
-  forDecls (TypeInstanceDeclaration _ _ _ _ cs _ tys _) = mconcat (concatMap (fmap f . constraintArgs) cs) `mappend` mconcat (fmap f tys)
+  forDecls (TypeInstanceDeclaration _ _ _ _ cs _ tys _) = mconcat (concatMap (fmap f . constraintArgs) cs) <> mconcat (fmap f tys)
   forDecls (TypeSynonymDeclaration _ _ _ ty) = f ty
   forDecls (TypeDeclaration td) = f (tydeclType td)
   forDecls _ = mempty
@@ -657,16 +654,16 @@ accumKinds
 accumKinds f = everythingOnValues mappend forDecls forValues (const mempty) (const mempty) (const mempty)
   where
   forDecls (DataDeclaration _ _ _ args dctors) =
-    foldMap (foldMap f . snd) args `mappend`
+    foldMap (foldMap f . snd) args <>
     foldMap (foldMap forTypes . snd) dctors
   forDecls (TypeClassDeclaration _ _ args implies _ _) =
-    foldMap (foldMap f . snd) args `mappend`
+    foldMap (foldMap f . snd) args <>
     foldMap (foldMap forTypes . constraintArgs) implies
   forDecls (TypeInstanceDeclaration _ _ _ _ cs _ tys _) =
-    foldMap (foldMap forTypes . constraintArgs) cs `mappend`
+    foldMap (foldMap forTypes . constraintArgs) cs <>
     foldMap forTypes tys
   forDecls (TypeSynonymDeclaration _ _ args ty) =
-    foldMap (foldMap f . snd) args `mappend`
+    foldMap (foldMap f . snd) args <>
     forTypes ty
   forDecls (TypeDeclaration td) = forTypes (tydeclType td)
   forDecls (ExternDeclaration _ _ ty) = forTypes ty
diff --git a/src/Language/PureScript/CodeGen/JS.hs b/src/Language/PureScript/CodeGen/JS.hs
index 266c560422..adf235f81e 100644
--- a/src/Language/PureScript/CodeGen/JS.hs
+++ b/src/Language/PureScript/CodeGen/JS.hs
@@ -19,7 +19,6 @@ import Data.List ((\\), intersect)
 import qualified Data.Foldable as F
 import qualified Data.Map as M
 import Data.Maybe (fromMaybe, isNothing)
-import Data.Monoid ((<>))
 import Data.String (fromString)
 import Data.Text (Text)
 import qualified Data.Text as T
diff --git a/src/Language/PureScript/CodeGen/JS/Common.hs b/src/Language/PureScript/CodeGen/JS/Common.hs
index 259cd4afa2..603b75d3c0 100644
--- a/src/Language/PureScript/CodeGen/JS/Common.hs
+++ b/src/Language/PureScript/CodeGen/JS/Common.hs
@@ -4,7 +4,6 @@ module Language.PureScript.CodeGen.JS.Common where
 import Prelude.Compat
 
 import Data.Char
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.Text as T
 
diff --git a/src/Language/PureScript/CodeGen/JS/Printer.hs b/src/Language/PureScript/CodeGen/JS/Printer.hs
index d8b59dc268..da67fa78eb 100644
--- a/src/Language/PureScript/CodeGen/JS/Printer.hs
+++ b/src/Language/PureScript/CodeGen/JS/Printer.hs
@@ -13,7 +13,6 @@ import Control.PatternArrows
 import qualified Control.Arrow as A
 
 import Data.Maybe (fromMaybe)
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.Text as T
 
diff --git a/src/Language/PureScript/CoreFn/Traversals.hs b/src/Language/PureScript/CoreFn/Traversals.hs
index 20b0cd320f..5415911863 100644
--- a/src/Language/PureScript/CoreFn/Traversals.hs
+++ b/src/Language/PureScript/CoreFn/Traversals.hs
@@ -50,27 +50,27 @@ everythingOnValues :: (r -> r -> r) ->
                       (Binder a -> r) ->
                       (CaseAlternative a -> r) ->
                       (Bind a -> r, Expr a -> r, Binder a -> r, CaseAlternative a -> r)
-everythingOnValues (<>) f g h i = (f', g', h', i')
+everythingOnValues (<>.) f g h i = (f', g', h', i')
   where
-  f' b@(NonRec _ _ e) = f b <> g' e
-  f' b@(Rec es) = foldl (<>) (f b) (map (g' . snd) es)
+  f' b@(NonRec _ _ e) = f b <>. g' e
+  f' b@(Rec es) = foldl (<>.) (f b) (map (g' . snd) es)
 
-  g' v@(Literal _ l) = foldl (<>) (g v) (map g' (extractLiteral l))
-  g' v@(Accessor _ _ e1) = g v <> g' e1
-  g' v@(ObjectUpdate _ obj vs) = foldl (<>) (g v <> g' obj) (map (g' . snd) vs)
-  g' v@(Abs _ _ e1) = g v <> g' e1
-  g' v@(App _ e1 e2) = g v <> g' e1 <> g' e2
-  g' v@(Case _ vs alts) = foldl (<>) (foldl (<>) (g v) (map g' vs)) (map i' alts)
-  g' v@(Let _ ds e1) = foldl (<>) (g v) (map f' ds) <> g' e1
+  g' v@(Literal _ l) = foldl (<>.) (g v) (map g' (extractLiteral l))
+  g' v@(Accessor _ _ e1) = g v <>. g' e1
+  g' v@(ObjectUpdate _ obj vs) = foldl (<>.) (g v <>. g' obj) (map (g' . snd) vs)
+  g' v@(Abs _ _ e1) = g v <>. g' e1
+  g' v@(App _ e1 e2) = g v <>. g' e1 <>. g' e2
+  g' v@(Case _ vs alts) = foldl (<>.) (foldl (<>.) (g v) (map g' vs)) (map i' alts)
+  g' v@(Let _ ds e1) = foldl (<>.) (g v) (map f' ds) <>. g' e1
   g' v = g v
 
-  h' b@(LiteralBinder _ l) = foldl (<>) (h b) (map h' (extractLiteral l))
-  h' b@(ConstructorBinder _ _ _ bs) = foldl (<>) (h b) (map h' bs)
-  h' b@(NamedBinder _ _ b1) = h b <> h' b1
+  h' b@(LiteralBinder _ l) = foldl (<>.) (h b) (map h' (extractLiteral l))
+  h' b@(ConstructorBinder _ _ _ bs) = foldl (<>.) (h b) (map h' bs)
+  h' b@(NamedBinder _ _ b1) = h b <>. h' b1
   h' b = h b
 
-  i' ca@(CaseAlternative bs (Right val)) = foldl (<>) (i ca) (map h' bs) <> g' val
-  i' ca@(CaseAlternative bs (Left gs)) = foldl (<>) (i ca) (map h' bs ++ concatMap (\(grd, val) -> [g' grd, g' val]) gs)
+  i' ca@(CaseAlternative bs (Right val)) = foldl (<>.) (i ca) (map h' bs) <>. g' val
+  i' ca@(CaseAlternative bs (Left gs)) = foldl (<>.) (i ca) (map h' bs ++ concatMap (\(grd, val) -> [g' grd, g' val]) gs)
 
   extractLiteral (ArrayLiteral xs) = xs
   extractLiteral (ObjectLiteral xs) = map snd xs
diff --git a/src/Language/PureScript/CoreImp/AST.hs b/src/Language/PureScript/CoreImp/AST.hs
index 36062336ae..b6dcad1446 100644
--- a/src/Language/PureScript/CoreImp/AST.hs
+++ b/src/Language/PureScript/CoreImp/AST.hs
@@ -201,24 +201,24 @@ everywhereTopDownM f = f >=> go where
   go other = f other
 
 everything :: (r -> r -> r) -> (AST -> r) -> AST -> r
-everything (<>) f = go where
-  go j@(Unary _ _ j1) = f j <> go j1
-  go j@(Binary _ _ j1 j2) = f j <> go j1 <> go j2
-  go j@(ArrayLiteral _ js) = foldl (<>) (f j) (map go js)
-  go j@(Indexer _ j1 j2) = f j <> go j1 <> go j2
-  go j@(ObjectLiteral _ js) = foldl (<>) (f j) (map (go . snd) js)
-  go j@(Function _ _ _ j1) = f j <> go j1
-  go j@(App _ j1 js) = foldl (<>) (f j <> go j1) (map go js)
-  go j@(Block _ js) = foldl (<>) (f j) (map go js)
-  go j@(VariableIntroduction _ _ (Just j1)) = f j <> go j1
-  go j@(Assignment _ j1 j2) = f j <> go j1 <> go j2
-  go j@(While _ j1 j2) = f j <> go j1 <> go j2
-  go j@(For _ _ j1 j2 j3) = f j <> go j1 <> go j2 <> go j3
-  go j@(ForIn _ _ j1 j2) = f j <> go j1 <> go j2
-  go j@(IfElse _ j1 j2 Nothing) = f j <> go j1 <> go j2
-  go j@(IfElse _ j1 j2 (Just j3)) = f j <> go j1 <> go j2 <> go j3
-  go j@(Return _ j1) = f j <> go j1
-  go j@(Throw _ j1) = f j <> go j1
-  go j@(InstanceOf _ j1 j2) = f j <> go j1 <> go j2
-  go j@(Comment _ _ j1) = f j <> go j1
+everything (<>.) f = go where
+  go j@(Unary _ _ j1) = f j <>. go j1
+  go j@(Binary _ _ j1 j2) = f j <>. go j1 <>. go j2
+  go j@(ArrayLiteral _ js) = foldl (<>.) (f j) (map go js)
+  go j@(Indexer _ j1 j2) = f j <>. go j1 <>. go j2
+  go j@(ObjectLiteral _ js) = foldl (<>.) (f j) (map (go . snd) js)
+  go j@(Function _ _ _ j1) = f j <>. go j1
+  go j@(App _ j1 js) = foldl (<>.) (f j <>. go j1) (map go js)
+  go j@(Block _ js) = foldl (<>.) (f j) (map go js)
+  go j@(VariableIntroduction _ _ (Just j1)) = f j <>. go j1
+  go j@(Assignment _ j1 j2) = f j <>. go j1 <>. go j2
+  go j@(While _ j1 j2) = f j <>. go j1 <>. go j2
+  go j@(For _ _ j1 j2 j3) = f j <>. go j1 <>. go j2 <>. go j3
+  go j@(ForIn _ _ j1 j2) = f j <>. go j1 <>. go j2
+  go j@(IfElse _ j1 j2 Nothing) = f j <>. go j1 <>. go j2
+  go j@(IfElse _ j1 j2 (Just j3)) = f j <>. go j1 <>. go j2 <>. go j3
+  go j@(Return _ j1) = f j <>. go j1
+  go j@(Throw _ j1) = f j <>. go j1
+  go j@(InstanceOf _ j1 j2) = f j <>. go j1 <>. go j2
+  go j@(Comment _ _ j1) = f j <>. go j1
   go other = f other
diff --git a/src/Language/PureScript/CoreImp/Optimizer/Inliner.hs b/src/Language/PureScript/CoreImp/Optimizer/Inliner.hs
index 391f9391d6..96001d3ef5 100644
--- a/src/Language/PureScript/CoreImp/Optimizer/Inliner.hs
+++ b/src/Language/PureScript/CoreImp/Optimizer/Inliner.hs
@@ -16,7 +16,6 @@ import Prelude.Compat
 import Control.Monad.Supply.Class (MonadSupply, freshName)
 
 import Data.Maybe (fromMaybe)
-import Data.Monoid ((<>))
 import Data.String (IsString, fromString)
 import Data.Text (Text)
 import qualified Data.Text as T
diff --git a/src/Language/PureScript/CoreImp/Optimizer/TCO.hs b/src/Language/PureScript/CoreImp/Optimizer/TCO.hs
index 0a5d949668..fcf49fcbef 100644
--- a/src/Language/PureScript/CoreImp/Optimizer/TCO.hs
+++ b/src/Language/PureScript/CoreImp/Optimizer/TCO.hs
@@ -4,7 +4,6 @@ module Language.PureScript.CoreImp.Optimizer.TCO (tco) where
 import Prelude.Compat
 
 import Data.Text (Text)
-import Data.Monoid ((<>))
 import Language.PureScript.CoreImp.AST
 import Language.PureScript.AST.SourcePos (SourceSpan)
 import Safe (headDef, tailSafe)
diff --git a/src/Language/PureScript/Docs/AsHtml.hs b/src/Language/PureScript/Docs/AsHtml.hs
index 80856c94cb..adeeab7c54 100644
--- a/src/Language/PureScript/Docs/AsHtml.hs
+++ b/src/Language/PureScript/Docs/AsHtml.hs
@@ -20,7 +20,6 @@ import Control.Monad (unless)
 import Data.Char (isUpper)
 import Data.Either (isRight)
 import Data.Maybe (fromMaybe)
-import Data.Monoid ((<>))
 import Data.Foldable (for_)
 import Data.String (fromString)
 
diff --git a/src/Language/PureScript/Docs/AsMarkdown.hs b/src/Language/PureScript/Docs/AsMarkdown.hs
index 6cb3b4e47b..13c513baa4 100644
--- a/src/Language/PureScript/Docs/AsMarkdown.hs
+++ b/src/Language/PureScript/Docs/AsMarkdown.hs
@@ -13,7 +13,6 @@ import Control.Monad.Error.Class (MonadError)
 import Control.Monad.Writer (Writer, tell, execWriter)
 
 import Data.Foldable (for_)
-import Data.Monoid ((<>))
 import Data.List (partition)
 import Data.Text (Text)
 import qualified Data.Text as T
diff --git a/src/Language/PureScript/Docs/Convert/ReExports.hs b/src/Language/PureScript/Docs/Convert/ReExports.hs
index 4d48cb14dd..241acaab49 100644
--- a/src/Language/PureScript/Docs/Convert/ReExports.hs
+++ b/src/Language/PureScript/Docs/Convert/ReExports.hs
@@ -14,7 +14,6 @@ import Control.Monad.Trans.State.Strict (execState)
 import Data.Either
 import Data.Map (Map)
 import Data.Maybe (mapMaybe)
-import Data.Monoid ((<>))
 import qualified Data.Map as Map
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -415,12 +414,13 @@ data TypeClassEnv = TypeClassEnv
   }
   deriving (Show)
 
+instance Semigroup TypeClassEnv where
+  (TypeClassEnv a1 b1 c1) <> (TypeClassEnv a2 b2 c2) =
+    TypeClassEnv (a1 <> a2) (b1 <> b2) (c1 <> c2)
+
 instance Monoid TypeClassEnv where
   mempty =
     TypeClassEnv mempty mempty mempty
-  mappend (TypeClassEnv a1 b1 c1)
-          (TypeClassEnv a2 b2 c2) =
-    TypeClassEnv (a1 <> a2) (b1 <> b2) (c1 <> c2)
 
 -- |
 -- Take a TypeClassEnv and handle all of the type class members in it, either
diff --git a/src/Language/PureScript/Docs/Convert/Single.hs b/src/Language/PureScript/Docs/Convert/Single.hs
index deaccf2db5..045fe34c4a 100644
--- a/src/Language/PureScript/Docs/Convert/Single.hs
+++ b/src/Language/PureScript/Docs/Convert/Single.hs
@@ -114,7 +114,7 @@ convertDeclaration (P.ValueDecl sa _ _ _ [P.MkUnguarded (P.TypedValue _ _ ty)])
 convertDeclaration (P.ValueDecl sa _ _ _ _) title =
   -- If no explicit type declaration was provided, insert a wildcard, so that
   -- the actual type will be added during type checking.
-  basicDeclaration sa title (ValueDeclaration P.TypeWildcard{})
+  basicDeclaration sa title (ValueDeclaration (P.TypeWildcard (fst sa)))
 convertDeclaration (P.ExternDeclaration sa _ ty) title =
   basicDeclaration sa title (ValueDeclaration ty)
 convertDeclaration (P.DataDeclaration sa dtype _ args ctors) title =
diff --git a/src/Language/PureScript/Docs/Prim.hs b/src/Language/PureScript/Docs/Prim.hs
index ed16e734af..0116788428 100644
--- a/src/Language/PureScript/Docs/Prim.hs
+++ b/src/Language/PureScript/Docs/Prim.hs
@@ -7,7 +7,6 @@ module Language.PureScript.Docs.Prim
   ) where
 
 import Prelude.Compat hiding (fail)
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.Text as T
 import qualified Data.Map as Map
diff --git a/src/Language/PureScript/Docs/Render.hs b/src/Language/PureScript/Docs/Render.hs
index 572449386e..c0c656589f 100644
--- a/src/Language/PureScript/Docs/Render.hs
+++ b/src/Language/PureScript/Docs/Render.hs
@@ -12,7 +12,6 @@ module Language.PureScript.Docs.Render where
 import Prelude.Compat
 
 import Data.Maybe (maybeToList)
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.Text as T
 
diff --git a/src/Language/PureScript/Docs/RenderedCode/RenderKind.hs b/src/Language/PureScript/Docs/RenderedCode/RenderKind.hs
index 3539a1244f..bbdbe8ce03 100644
--- a/src/Language/PureScript/Docs/RenderedCode/RenderKind.hs
+++ b/src/Language/PureScript/Docs/RenderedCode/RenderKind.hs
@@ -12,7 +12,6 @@ import Prelude.Compat
 import Control.Arrow (ArrowPlus(..))
 import Control.PatternArrows as PA
 
-import Data.Monoid ((<>))
 import Data.Maybe (fromMaybe)
 import qualified Data.Text as T
 
diff --git a/src/Language/PureScript/Docs/RenderedCode/RenderType.hs b/src/Language/PureScript/Docs/RenderedCode/RenderType.hs
index 15f51dc94c..3857dfd171 100644
--- a/src/Language/PureScript/Docs/RenderedCode/RenderType.hs
+++ b/src/Language/PureScript/Docs/RenderedCode/RenderType.hs
@@ -13,7 +13,6 @@ module Language.PureScript.Docs.RenderedCode.RenderType
 import Prelude.Compat
 
 import Data.Maybe (fromMaybe)
-import Data.Monoid ((<>))
 import Data.Text (Text)
 
 import Control.Arrow ((<+>))
diff --git a/src/Language/PureScript/Docs/RenderedCode/Types.hs b/src/Language/PureScript/Docs/RenderedCode/Types.hs
index 0d64e301b1..ecf1b0a9fb 100644
--- a/src/Language/PureScript/Docs/RenderedCode/Types.hs
+++ b/src/Language/PureScript/Docs/RenderedCode/Types.hs
@@ -49,7 +49,6 @@ import GHC.Generics (Generic)
 import Control.DeepSeq (NFData)
 import Control.Monad.Error.Class (MonadError(..))
 
-import Data.Monoid ((<>))
 import Data.Aeson.BetterErrors (Parse, nth, withText, withValue, toAesonParser, perhaps, asText, eachInArray)
 import qualified Data.Aeson as A
 import Data.Text (Text)
@@ -248,7 +247,7 @@ asRenderedCodeElement =
 --
 newtype RenderedCode
   = RC { unRC :: [RenderedCodeElement] }
-  deriving (Show, Eq, Ord, Monoid)
+  deriving (Show, Eq, Ord, Semigroup, Monoid)
 
 instance A.ToJSON RenderedCode where
   toJSON (RC elems) = A.toJSON elems
diff --git a/src/Language/PureScript/Docs/Utils/MonoidExtras.hs b/src/Language/PureScript/Docs/Utils/MonoidExtras.hs
index a9d317e603..0d4d0bfd7f 100644
--- a/src/Language/PureScript/Docs/Utils/MonoidExtras.hs
+++ b/src/Language/PureScript/Docs/Utils/MonoidExtras.hs
@@ -6,4 +6,3 @@ mintersperse :: (Monoid m) => m -> [m] -> m
 mintersperse _ []       = mempty
 mintersperse _ [x]      = x
 mintersperse sep (x:xs) = x <> sep <> mintersperse sep xs
-
diff --git a/src/Language/PureScript/Errors.hs b/src/Language/PureScript/Errors.hs
index 135f98aa2f..0028f3b233 100644
--- a/src/Language/PureScript/Errors.hs
+++ b/src/Language/PureScript/Errors.hs
@@ -186,7 +186,7 @@ errorCode em = case unwrapErrorMessage em of
 -- | A stack trace for an error
 newtype MultipleErrors = MultipleErrors
   { runMultipleErrors :: [ErrorMessage]
-  } deriving (Show, Monoid)
+  } deriving (Show, Semigroup, Monoid)
 
 -- | Check whether a collection of errors is empty or not.
 nonEmpty :: MultipleErrors -> Bool
diff --git a/src/Language/PureScript/Errors/JSON.hs b/src/Language/PureScript/Errors/JSON.hs
index 65f872d23b..f552f91f03 100644
--- a/src/Language/PureScript/Errors/JSON.hs
+++ b/src/Language/PureScript/Errors/JSON.hs
@@ -6,7 +6,6 @@ import Prelude.Compat
 
 import qualified Data.Aeson.TH as A
 import qualified Data.List.NonEmpty as NEL
-import Data.Monoid ((<>))
 import qualified Data.Text as T
 import Data.Text (Text)
 
diff --git a/src/Language/PureScript/Hierarchy.hs b/src/Language/PureScript/Hierarchy.hs
index 837fd3a33a..db6b9b12f6 100644
--- a/src/Language/PureScript/Hierarchy.hs
+++ b/src/Language/PureScript/Hierarchy.hs
@@ -19,7 +19,6 @@ import           Prelude.Compat
 import           Protolude (ordNub)
 
 import           Data.List (sort)
-import           Data.Monoid ((<>))
 import qualified Data.Text as T
 import qualified Language.PureScript as P
 
diff --git a/src/Language/PureScript/Ide/Filter.hs b/src/Language/PureScript/Ide/Filter.hs
index cdb29f4cbd..b08bb06d0e 100644
--- a/src/Language/PureScript/Ide/Filter.hs
+++ b/src/Language/PureScript/Ide/Filter.hs
@@ -35,7 +35,7 @@ import           Language.PureScript.Ide.Util
 import qualified Language.PureScript           as P
 
 newtype Filter = Filter (Endo [Module])
-  deriving (Monoid)
+  deriving (Semigroup, Monoid)
 
 type Module = (P.ModuleName, [IdeDeclarationAnn])
 
diff --git a/src/Language/PureScript/Ide/Matcher.hs b/src/Language/PureScript/Ide/Matcher.hs
index 531a29e43c..e5bf21e504 100644
--- a/src/Language/PureScript/Ide/Matcher.hs
+++ b/src/Language/PureScript/Ide/Matcher.hs
@@ -35,7 +35,7 @@ import           Text.Regex.TDFA               ((=~))
 
 type ScoredMatch a = (Match a, Double)
 
-newtype Matcher a = Matcher (Endo [Match a]) deriving (Monoid)
+newtype Matcher a = Matcher (Endo [Match a]) deriving (Semigroup, Monoid)
 
 instance FromJSON (Matcher IdeDeclarationAnn) where
   parseJSON = withObject "matcher" $ \o -> do
diff --git a/src/Language/PureScript/Interactive.hs b/src/Language/PureScript/Interactive.hs
index 6fbfc5dbb8..efc7a1e44f 100644
--- a/src/Language/PureScript/Interactive.hs
+++ b/src/Language/PureScript/Interactive.hs
@@ -16,7 +16,6 @@ import           Protolude (ordNub)
 import           Data.List (sort, find, foldl')
 import           Data.Maybe (fromMaybe, mapMaybe)
 import qualified Data.Map as M
-import           Data.Monoid ((<>))
 import qualified Data.Set as S
 import           Data.Text (Text)
 import qualified Data.Text as T
diff --git a/src/Language/PureScript/Interactive/Printer.hs b/src/Language/PureScript/Interactive/Printer.hs
index 38022a7dc3..608129465e 100644
--- a/src/Language/PureScript/Interactive/Printer.hs
+++ b/src/Language/PureScript/Interactive/Printer.hs
@@ -5,7 +5,6 @@ import           Prelude.Compat
 import           Data.List (intersperse)
 import qualified Data.Map as M
 import           Data.Maybe (mapMaybe)
-import           Data.Monoid ((<>))
 import qualified Data.Text as T
 import           Data.Text (Text)
 import qualified Language.PureScript as P
diff --git a/src/Language/PureScript/Kinds.hs b/src/Language/PureScript/Kinds.hs
index 2088a3fb06..01df9dca87 100644
--- a/src/Language/PureScript/Kinds.hs
+++ b/src/Language/PureScript/Kinds.hs
@@ -102,8 +102,8 @@ everywhereOnKindsM f = go
   go other = f other
 
 everythingOnKinds :: (r -> r -> r) -> (Kind -> r) -> Kind -> r
-everythingOnKinds (<>) f = go
+everythingOnKinds (<>.) f = go
   where
-  go k@(Row k1) = f k <> go k1
-  go k@(FunKind k1 k2) = f k <> go k1 <> go k2
+  go k@(Row k1) = f k <>. go k1
+  go k@(FunKind k1 k2) = f k <>. go k1 <>. go k2
   go other = f other
diff --git a/src/Language/PureScript/Label.hs b/src/Language/PureScript/Label.hs
index b00db4fe9b..accd31463e 100644
--- a/src/Language/PureScript/Label.hs
+++ b/src/Language/PureScript/Label.hs
@@ -17,6 +17,6 @@ import Language.PureScript.PSString (PSString)
 -- because records are indexable by PureScript strings at runtime.
 --
 newtype Label = Label { runLabel :: PSString }
-  deriving (Show, Eq, Ord, IsString, Monoid, A.ToJSON, A.FromJSON, Generic)
+  deriving (Show, Eq, Ord, IsString, Semigroup, Monoid, A.ToJSON, A.FromJSON, Generic)
 
 instance NFData Label
diff --git a/src/Language/PureScript/Linter.hs b/src/Language/PureScript/Linter.hs
index 59f936af25..49ede59811 100644
--- a/src/Language/PureScript/Linter.hs
+++ b/src/Language/PureScript/Linter.hs
@@ -10,7 +10,6 @@ import Control.Monad.Writer.Class
 
 import Data.List ((\\))
 import Data.Maybe (mapMaybe)
-import Data.Monoid
 import qualified Data.Set as S
 import Data.Text (Text)
 
diff --git a/src/Language/PureScript/Linter/Exhaustive.hs b/src/Language/PureScript/Linter/Exhaustive.hs
index 1965925639..4278f509a3 100644
--- a/src/Language/PureScript/Linter/Exhaustive.hs
+++ b/src/Language/PureScript/Linter/Exhaustive.hs
@@ -20,7 +20,6 @@ import Control.Monad.Supply.Class (MonadSupply, fresh, freshName)
 import Data.Function (on)
 import Data.List (foldl', sortBy)
 import Data.Maybe (fromMaybe)
-import Data.Monoid ((<>))
 import qualified Data.Map as M
 import Data.Text (Text)
 import qualified Data.Text as T
diff --git a/src/Language/PureScript/Make/Actions.hs b/src/Language/PureScript/Make/Actions.hs
index 254b83bd5e..53f3aca438 100644
--- a/src/Language/PureScript/Make/Actions.hs
+++ b/src/Language/PureScript/Make/Actions.hs
@@ -24,7 +24,6 @@ import           Data.Foldable (for_, minimum)
 import qualified Data.List.NonEmpty as NEL
 import qualified Data.Map as M
 import           Data.Maybe (fromMaybe)
-import           Data.Monoid ((<>))
 import qualified Data.Set as S
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as TE
diff --git a/src/Language/PureScript/Names.hs b/src/Language/PureScript/Names.hs
index 16f135f221..e2327c1cc1 100644
--- a/src/Language/PureScript/Names.hs
+++ b/src/Language/PureScript/Names.hs
@@ -16,7 +16,6 @@ import Control.DeepSeq (NFData)
 import GHC.Generics (Generic)
 import Data.Aeson
 import Data.Aeson.TH
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.Text as T
 
diff --git a/src/Language/PureScript/PSString.hs b/src/Language/PureScript/PSString.hs
index 0dcb3b40cc..f466257f2a 100644
--- a/src/Language/PureScript/PSString.hs
+++ b/src/Language/PureScript/PSString.hs
@@ -21,7 +21,6 @@ import Control.Applicative ((<|>))
 import Data.Char (chr)
 import Data.Bits (shiftR)
 import Data.List (unfoldr)
-import Data.Monoid ((<>))
 import Data.Scientific (toBoundedInteger)
 import Data.String (IsString(..))
 import Data.ByteString (ByteString)
@@ -52,7 +51,7 @@ import qualified Data.Aeson.Types as A
 -- and arrays of UTF-16 code units (integers) otherwise.
 --
 newtype PSString = PSString { toUTF16CodeUnits :: [Word16] }
-  deriving (Eq, Ord, Monoid, Generic)
+  deriving (Eq, Ord, Semigroup, Monoid, Generic)
 
 instance NFData PSString
 
diff --git a/src/Language/PureScript/Parser/Common.hs b/src/Language/PureScript/Parser/Common.hs
index 6f21f9f16d..0b430baabe 100644
--- a/src/Language/PureScript/Parser/Common.hs
+++ b/src/Language/PureScript/Parser/Common.hs
@@ -6,7 +6,6 @@ import           Prelude.Compat
 import           Control.Applicative ((<|>))
 import           Control.Monad (guard)
 import           Data.Maybe (fromMaybe)
-import           Data.Monoid ((<>))
 import           Data.Text (Text)
 import qualified Data.Text as T
 import           Language.PureScript.AST.SourcePos
diff --git a/src/Language/PureScript/Parser/Declarations.hs b/src/Language/PureScript/Parser/Declarations.hs
index 12fc38f9ab..bfc77014cb 100644
--- a/src/Language/PureScript/Parser/Declarations.hs
+++ b/src/Language/PureScript/Parser/Declarations.hs
@@ -25,7 +25,6 @@ import           Control.Monad.Error.Class (MonadError(..))
 import           Control.Parallel.Strategies (withStrategy, parList, rseq)
 import           Data.Functor (($>))
 import           Data.Maybe (fromMaybe)
-import           Data.Monoid ((<>))
 import qualified Data.Set as S
 import           Data.Text (Text)
 import           Language.PureScript.AST
diff --git a/src/Language/PureScript/Parser/Lexer.hs b/src/Language/PureScript/Parser/Lexer.hs
index 71812e8977..377d9b18a8 100644
--- a/src/Language/PureScript/Parser/Lexer.hs
+++ b/src/Language/PureScript/Parser/Lexer.hs
@@ -70,7 +70,6 @@ import Control.Applicative ((<|>))
 import Control.Monad (void, guard)
 import Control.Monad.Identity (Identity)
 import Data.Char (isSpace, isAscii, isSymbol, isAlphaNum)
-import Data.Monoid ((<>))
 import Data.String (fromString)
 import Data.Text (Text)
 import qualified Data.Text as T
diff --git a/src/Language/PureScript/Pretty/Common.hs b/src/Language/PureScript/Pretty/Common.hs
index b7280232e7..e26fa2a3b9 100644
--- a/src/Language/PureScript/Pretty/Common.hs
+++ b/src/Language/PureScript/Pretty/Common.hs
@@ -10,7 +10,6 @@ import Prelude.Compat
 import Control.Monad.State (StateT, modify, get)
 
 import Data.List (elemIndices, intersperse)
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.Text as T
 import Data.Char (isUpper)
@@ -55,11 +54,12 @@ newtype StrPos = StrPos (SourcePos, Text, [SMap])
 -- appropriately and advancing source mappings on the right hand side to account for
 -- the length of the left.
 --
+instance Semigroup StrPos where
+  StrPos (a,b,c) <> StrPos (a',b',c') = StrPos (a `addPos` a', b <> b', c ++ (bumpPos a <$> c'))
+
 instance Monoid StrPos where
   mempty = StrPos (SourcePos 0 0, "", [])
 
-  StrPos (a,b,c) `mappend` StrPos (a',b',c') = StrPos (a `addPos` a', b <> b', c ++ (bumpPos a <$> c'))
-
   mconcat ms =
     let s' = foldMap (\(StrPos(_, s, _)) -> s) ms
         (p, maps) = foldl plus (SourcePos 0 0, []) ms
@@ -88,7 +88,7 @@ instance Emit StrPos where
       mapping = SMap (T.pack file) startPos zeroPos
       zeroPos = SourcePos 0 0
 
-newtype PlainString = PlainString Text deriving Monoid
+newtype PlainString = PlainString Text deriving (Semigroup, Monoid)
 
 runPlainString :: PlainString -> Text
 runPlainString (PlainString s) = s
diff --git a/src/Language/PureScript/Pretty/Kinds.hs b/src/Language/PureScript/Pretty/Kinds.hs
index 24d4451e78..9f950af9f7 100644
--- a/src/Language/PureScript/Pretty/Kinds.hs
+++ b/src/Language/PureScript/Pretty/Kinds.hs
@@ -10,7 +10,6 @@ import Prelude.Compat
 import Control.Arrow (ArrowPlus(..))
 import Control.PatternArrows as PA
 
-import Data.Monoid ((<>))
 import Data.Maybe (fromMaybe)
 import qualified Data.Text as T
 import Data.Text (Text)
diff --git a/src/Language/PureScript/Pretty/Types.hs b/src/Language/PureScript/Pretty/Types.hs
index bee62db14c..40c2956eb5 100644
--- a/src/Language/PureScript/Pretty/Types.hs
+++ b/src/Language/PureScript/Pretty/Types.hs
@@ -14,7 +14,7 @@ module Language.PureScript.Pretty.Types
   , prettyPrintObjectKey
   ) where
 
-import Prelude.Compat
+import Prelude.Compat hiding ((<>))
 
 import Control.Arrow ((<+>))
 import Control.PatternArrows as PA
diff --git a/src/Language/PureScript/Pretty/Values.hs b/src/Language/PureScript/Pretty/Values.hs
index bbabf0821c..7902526c03 100644
--- a/src/Language/PureScript/Pretty/Values.hs
+++ b/src/Language/PureScript/Pretty/Values.hs
@@ -7,7 +7,7 @@ module Language.PureScript.Pretty.Values
   , prettyPrintBinderAtom
   ) where
 
-import Prelude.Compat
+import Prelude.Compat hiding ((<>))
 
 import Control.Arrow (second)
 
diff --git a/src/Language/PureScript/Publish.hs b/src/Language/PureScript/Publish.hs
index 73545bf488..7d1c6306d0 100644
--- a/src/Language/PureScript/Publish.hs
+++ b/src/Language/PureScript/Publish.hs
@@ -36,7 +36,8 @@ import qualified Data.Text as T
 import Data.Time.Clock (UTCTime)
 import Data.Time.Clock.POSIX (posixSecondsToUTCTime)
 import Data.Version
-import qualified Data.SPDX as SPDX
+import qualified Distribution.SPDX as SPDX
+import qualified Distribution.Parsec.Class as CabalParsec
 
 import System.Directory (doesFileExist)
 import System.FilePath.Glob (globDir1)
@@ -230,7 +231,11 @@ checkLicense pkgMeta =
 -- Check if a string is a valid SPDX license expression.
 --
 isValidSPDX :: String -> Bool
-isValidSPDX = (== 1) . length . SPDX.parseExpression
+isValidSPDX input = case CabalParsec.simpleParsec input of
+  Nothing -> False
+  Just SPDX.NONE -> False
+  Just _ -> True
+
 
 extractGithub :: Text -> Maybe (D.GithubUser, D.GithubRepo)
 extractGithub = stripGitHubPrefixes
diff --git a/src/Language/PureScript/Publish/ErrorsWarnings.hs b/src/Language/PureScript/Publish/ErrorsWarnings.hs
index 806739574c..38ebc36aeb 100644
--- a/src/Language/PureScript/Publish/ErrorsWarnings.hs
+++ b/src/Language/PureScript/Publish/ErrorsWarnings.hs
@@ -311,11 +311,12 @@ data CollectedWarnings = CollectedWarnings
   }
   deriving (Show, Eq, Ord)
 
+instance Semigroup CollectedWarnings where
+  (CollectedWarnings as bs cs d es) <> (CollectedWarnings as' bs' cs' d' es') =
+    CollectedWarnings (as <> as') (bs <> bs') (cs <> cs') (d <> d') (es <> es')
+
 instance Monoid CollectedWarnings where
   mempty = CollectedWarnings mempty mempty mempty mempty mempty
-  mappend (CollectedWarnings as bs cs d es)
-          (CollectedWarnings as' bs' cs' d' es') =
-    CollectedWarnings (as <> as') (bs <> bs') (cs <> cs') (d <> d') (es <> es')
 
 collectWarnings :: [PackageWarning] -> CollectedWarnings
 collectWarnings = foldMap singular
diff --git a/src/Language/PureScript/Renamer.hs b/src/Language/PureScript/Renamer.hs
index b99cd9d2ae..4ee82ad0d3 100644
--- a/src/Language/PureScript/Renamer.hs
+++ b/src/Language/PureScript/Renamer.hs
@@ -10,7 +10,6 @@ import Control.Monad.State
 import Data.List (find)
 import Data.Maybe (fromJust, fromMaybe)
 import qualified Data.Map as M
-import Data.Monoid ((<>))
 import qualified Data.Set as S
 import qualified Data.Text as T
 
diff --git a/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs b/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs
index a91cbe72fc..351cb3e0bf 100755
--- a/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs
+++ b/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs
@@ -12,7 +12,6 @@ import           Control.Monad.Supply.Class (MonadSupply)
 import           Data.Foldable (for_)
 import           Data.List (foldl', find, sortBy, unzip5)
 import qualified Data.Map as M
-import           Data.Monoid ((<>))
 import           Data.Maybe (fromMaybe, mapMaybe)
 import           Data.Ord (comparing)
 import qualified Data.Set as S
@@ -42,13 +41,15 @@ data NewtypeDerivedInstances = NewtypeDerivedInstances
   -- ^ A list of newtype instances which were derived in this module.
   } deriving Show
 
-instance Monoid NewtypeDerivedInstances where
-  mempty = NewtypeDerivedInstances mempty mempty
-  mappend x y =
+instance Semigroup NewtypeDerivedInstances where
+  x <> y =
     NewtypeDerivedInstances { ndiClasses          = ndiClasses          x <> ndiClasses          y
                             , ndiDerivedInstances = ndiDerivedInstances x <> ndiDerivedInstances y
                             }
 
+instance Monoid NewtypeDerivedInstances where
+  mempty = NewtypeDerivedInstances mempty mempty
+
 -- | Extract the name of the newtype appearing in the last type argument of
 -- a derived newtype instance.
 --
diff --git a/src/Language/PureScript/TypeChecker.hs b/src/Language/PureScript/TypeChecker.hs
index 3e293e3f07..dce0b28429 100644
--- a/src/Language/PureScript/TypeChecker.hs
+++ b/src/Language/PureScript/TypeChecker.hs
@@ -22,7 +22,6 @@ import Control.Lens ((^..), _1, _2)
 import Data.Foldable (for_, traverse_, toList)
 import Data.List (nub, nubBy, (\\), sort, group)
 import Data.Maybe
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.List.NonEmpty as NEL
 import qualified Data.Map as M
diff --git a/src/Language/PureScript/TypeChecker/Entailment.hs b/src/Language/PureScript/TypeChecker/Entailment.hs
index b11f064f69..13f8697bfd 100644
--- a/src/Language/PureScript/TypeChecker/Entailment.hs
+++ b/src/Language/PureScript/TypeChecker/Entailment.hs
@@ -135,14 +135,15 @@ data Matched t
   | Unknown
   deriving (Eq, Show, Functor)
 
+instance Semigroup t => Semigroup (Matched t) where
+  (Match l) <> (Match r) = Match (l <> r)
+  Apart     <> _         = Apart
+  _         <> Apart     = Apart
+  _         <> _         = Unknown
+
 instance Monoid t => Monoid (Matched t) where
   mempty = Match mempty
 
-  mappend (Match l) (Match r) = Match (l <> r)
-  mappend Apart     _         = Apart
-  mappend _         Apart     = Apart
-  mappend _         _         = Unknown
-
 -- | Check that the current set of type class dictionaries entail the specified type class goal, and, if so,
 -- return a type class dictionary reference.
 entails
diff --git a/src/Language/PureScript/TypeChecker/Skolems.hs b/src/Language/PureScript/TypeChecker/Skolems.hs
index f80d87e177..ed7659c92f 100644
--- a/src/Language/PureScript/TypeChecker/Skolems.hs
+++ b/src/Language/PureScript/TypeChecker/Skolems.hs
@@ -14,7 +14,6 @@ import Control.Monad.Error.Class (MonadError(..))
 import Control.Monad.State.Class (MonadState(..), gets, modify)
 import Data.Foldable (traverse_)
 import Data.Functor.Identity (Identity(), runIdentity)
-import Data.Monoid
 import Data.Set (Set, fromList, notMember)
 import Data.Text (Text)
 import Language.PureScript.AST
diff --git a/src/Language/PureScript/TypeChecker/Types.hs b/src/Language/PureScript/TypeChecker/Types.hs
index 920d159a6b..51dac649e6 100644
--- a/src/Language/PureScript/TypeChecker/Types.hs
+++ b/src/Language/PureScript/TypeChecker/Types.hs
@@ -39,7 +39,6 @@ import Data.Either (partitionEithers)
 import Data.Functor (($>))
 import Data.List (transpose, (\\), partition, delete)
 import Data.Maybe (fromMaybe)
-import Data.Monoid ((<>))
 import Data.Traversable (for)
 import qualified Data.List.NonEmpty as NEL
 import qualified Data.Map as M
diff --git a/src/Language/PureScript/TypeClassDictionaries.hs b/src/Language/PureScript/TypeClassDictionaries.hs
index af00286035..84b569ca80 100644
--- a/src/Language/PureScript/TypeClassDictionaries.hs
+++ b/src/Language/PureScript/TypeClassDictionaries.hs
@@ -7,7 +7,6 @@ import Prelude.Compat
 
 import GHC.Generics (Generic)
 import Control.DeepSeq (NFData)
-import Data.Monoid ((<>))
 import Data.Text (Text, pack)
 
 import Language.PureScript.Names
diff --git a/src/Language/PureScript/Types.hs b/src/Language/PureScript/Types.hs
index d600bf47f7..3ec79431a1 100644
--- a/src/Language/PureScript/Types.hs
+++ b/src/Language/PureScript/Types.hs
@@ -18,7 +18,6 @@ import qualified Data.Aeson.TH as A
 import Data.List (sortBy)
 import Data.Ord (comparing)
 import Data.Maybe (fromMaybe)
-import Data.Monoid ((<>))
 import Data.Text (Text)
 import qualified Data.Text as T
 import GHC.Generics (Generic)
diff --git a/stack.yaml b/stack.yaml
index 54c5cf306b..42dbab2418 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-11.7
+resolver: lts-12.0
 packages:
 - '.'
 extra-deps:
diff --git a/tests/TestCompiler.hs b/tests/TestCompiler.hs
index 9c3bed7a0f..2585f2507e 100644
--- a/tests/TestCompiler.hs
+++ b/tests/TestCompiler.hs
@@ -40,7 +40,6 @@ import Control.Monad
 import Control.Arrow ((***), (>>>))
 
 import Control.Monad.Reader
-import Control.Monad.Writer.Strict
 import Control.Monad.Trans.Except
 
 import System.Exit
diff --git a/tests/TestCoreFn.hs b/tests/TestCoreFn.hs
index 7c2722038a..2fcb158291 100644
--- a/tests/TestCoreFn.hs
+++ b/tests/TestCoreFn.hs
@@ -9,7 +9,7 @@ import Prelude ()
 import Prelude.Compat
 
 import Data.Aeson
-import Data.Aeson.Types
+import Data.Aeson.Types as Aeson
 import Data.Version
 
 import Language.PureScript.AST.Literals
@@ -37,7 +37,7 @@ parseMod m =
   in snd <$> parseModule (moduleToJSON v m)
 
 isSuccess :: Result a -> Bool
-isSuccess (Success _) = True
+isSuccess (Aeson.Success _) = True
 isSuccess _           = False
 
 spec :: Spec
@@ -52,42 +52,42 @@ spec = context "CoreFnFromJsonTest" $ do
     r `shouldSatisfy` isSuccess
     case r of
       Error _   -> return ()
-      Success m -> moduleName m `shouldBe` mn
+      Aeson.Success m -> moduleName m `shouldBe` mn
 
   specify "should parse source span" $ do
     let r = parseMod $ Module ss [] mn mp [] [] [] []
     r `shouldSatisfy` isSuccess
     case r of
       Error _   -> return ()
-      Success m -> moduleSourceSpan m `shouldBe` ss
+      Aeson.Success m -> moduleSourceSpan m `shouldBe` ss
 
   specify "should parse module path" $ do
     let r = parseMod $ Module ss [] mn mp [] [] [] []
     r `shouldSatisfy` isSuccess
     case r of
       Error _   -> return ()
-      Success m -> modulePath m `shouldBe` mp
+      Aeson.Success m -> modulePath m `shouldBe` mp
 
   specify "should parse imports" $ do
     let r = parseMod $ Module ss [] mn mp [(ann, mn)] [] [] []
     r `shouldSatisfy` isSuccess
     case r of
       Error _   -> return ()
-      Success m -> moduleImports m `shouldBe` [(ann, mn)]
+      Aeson.Success m -> moduleImports m `shouldBe` [(ann, mn)]
 
   specify "should parse exports" $ do
     let r = parseMod $ Module ss [] mn mp [] [Ident "exp"] [] []
     r `shouldSatisfy` isSuccess
     case r of
       Error _   -> return ()
-      Success m -> moduleExports m `shouldBe` [Ident "exp"]
+      Aeson.Success m -> moduleExports m `shouldBe` [Ident "exp"]
 
   specify "should parse foreign" $ do
     let r = parseMod $ Module ss [] mn mp [] [] [Ident "exp"] []
     r `shouldSatisfy` isSuccess
     case r of
       Error _   -> return ()
-      Success m -> moduleForeign m `shouldBe` [Ident "exp"]
+      Aeson.Success m -> moduleForeign m `shouldBe` [Ident "exp"]
 
   context "Expr" $ do
     specify "should parse literals" $ do
diff --git a/tests/TestPrimDocs.hs b/tests/TestPrimDocs.hs
index 1eb68d50e8..584c8a9681 100644
--- a/tests/TestPrimDocs.hs
+++ b/tests/TestPrimDocs.hs
@@ -3,7 +3,6 @@ module TestPrimDocs where
 import Prelude
 
 import Control.Monad
-import Data.Monoid ((<>))
 import Data.List ((\\))
 import qualified Data.Map as Map
 import qualified Data.Set as Set