fix monoid definition, remove obsolete version bounds

djembe.cabal

@@ -22,12 +22,12 @@ library
                        Drum
   -- other-modules:       
   -- other-extensions:    
-  build-depends:       base >=4.6 && <4.9
-                      ,lens >=4.7 && <4.14
+  build-depends:       base
+                      ,lens
                       ,hmidi >= 0.2.1 && <3.0
                       ,random >=1.0 && <1.2
-                      ,QuickCheck >=2.7 && <2.9
-                      ,hspec >=2.1 && <2.3
+                      ,QuickCheck
+                      ,hspec
                       ,mtl
   hs-source-dirs:      src
   default-language:    Haskell2010

src/Types.hs

@@ -107,10 +107,12 @@ instance Monad Composition where
     let (Composition (b', a')) = k a
     in Composition (Series b b', a')
 
+instance Semigroup (Composition ()) where
+  (Composition (b1, _)) <> (Composition (b2, _))
+    = Composition (Parallel b1 b2, ())
+
 instance Monoid (Composition ()) where
   mempty = Composition (None, ())
-  mappend (Composition (b1, _)) (Composition (b2, _))
-    = Composition (Parallel b1 b2, ())
 
 -- | Lift a function on `Hit`s over a `Composition`
 cmap :: (Hit -> Hit) -> Composition a -> Composition a

stack.yaml

@@ -1,5 +1,5 @@
 flags: {}
 packages:
 - '.'
-extra-deps: [hmidi-0.2.2.0]
-resolver: lts-2.22
+extra-deps: [hmidi-0.2.2.1]
+resolver: lts-16.1