diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,37 @@
+# HasCacBDD Changelog
+
+## upcoming
+
+- ...
+
+## v0.2.0.0 (2023-11-23)
+
+- rename `forall` (soon a keyword in GHC) to `forall_` and `exists` to `exists_`
+
+## v0.1.0.4 (2023-02-03)
+
+Maintenance release.
+
+- Faster subsOf and sizeOf.
+
+## v0.1.0.3 (2020-06-30)
+
+Maintenance release.
+
+- fix an error which caused `svgGraph` to hang on long outputs.
+- add `Read` and `Eq` classes for BddTree.
+- a few more tests.
+
+## v0.1.0.2 (2019-06-19)
+
+Correction to extra library paths defined in custom `Setup.hs`. This should fix problems when HasCacBDD is used as a dependency in projects with recent stack versions.
+
+## v0.1.0.1 (2019-01-24)
+
+- new functions: `relabelFun`, `substit`, `substitSimul`
+- simplified test suite
+- improve documentation and hints to get started
+
+## v0.1.0.0 (2017-03-09)
+
+First complete release, also available on hackage.
diff --git a/HasCacBDD.cabal b/HasCacBDD.cabal
--- a/HasCacBDD.cabal
+++ b/HasCacBDD.cabal
@@ -1,5 +1,5 @@
 name:                HasCacBDD
-version:             0.1.0.4
+version:             0.2.0.0
 synopsis:            Haskell bindings for CacBDD
 homepage:            https://github.com/m4lvin/HasCacBDD
 license:             GPL-2
@@ -25,6 +25,9 @@
   cpp/OriginalMakefile
   cpp/README
 
+extra-doc-files:
+  CHANGELOG.md
+
 source-repository head
   type:     git
   location: git://github.com/m4lvin/HasCacBDD.git
@@ -38,8 +41,8 @@
   exposed-modules:     Data.HasCacBDD,
                        Data.HasCacBDD.Visuals
   build-depends:       base >=4.8 && < 5,
-                       process >= 1.1,
-                       QuickCheck
+                       process >= 1.1 && < 1.7,
+                       QuickCheck >= 2.4 && < 2.15
   default-language:    Haskell2010
   hs-source-dirs:      hs
   extra-libraries:     stdc++, CacBDD
@@ -53,6 +56,6 @@
   hs-source-dirs:      tests
   build-depends:       base >=4.8,
                        HasCacBDD,
-                       hspec,
+                       hspec < 2.12,
                        QuickCheck > 2.4
   ghc-options:         -Wall -threaded
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@
 
 [![Release](https://img.shields.io/github/release/m4lvin/HasCacBDD.svg)](https://github.com/m4lvin/HasCacBDD/releases)
 [![Hackage](https://img.shields.io/hackage/v/HasCacBDD.svg)](https://hackage.haskell.org/package/HasCacBDD)
+[![GitLab CI](https://gitlab.com/m4lvin/HasCacBDD/badges/master/pipeline.svg)](https://gitlab.com/m4lvin/HasCacBDD/-/pipelines)
+[![Test Coverage](https://gitlab.com/m4lvin/HasCacBDD/badges/master/coverage.svg)](https://gitlab.com/m4lvin/HasCacBDD/-/jobs/artifacts/master/file/hpc/combined/all/hpc_index.html?job=test)
 
 Haskell bindings for CacBDD, a Binary Decision Diagram (BDD) package with dynamic cache management.
 
@@ -27,7 +29,9 @@
     Note: `stack ghci` apparently does not work with the shared library.
     You really need `stack build` and then `stack exec ghci`.
 
-3. Play :-)
+    To use cabal instead of stack: `cabal build`, then `cabal exec ghci` and then `:set -package HasCacBDD`.
+
+3. Now you can play with Boolean functions :-)
 
        λ> import Data.HasCacBDD
        λ> var 5
diff --git a/hs/Data/HasCacBDD.hs b/hs/Data/HasCacBDD.hs
--- a/hs/Data/HasCacBDD.hs
+++ b/hs/Data/HasCacBDD.hs
@@ -8,7 +8,7 @@
   top, bot, var,
   -- * Combination and Manipulation of BDDs
   neg, con, dis, imp, equ, xor, conSet, disSet, xorSet,
-  exists, forall, forallSet, existsSet,
+  exists_, forall_, existsSet, forallSet,
   restrict, restrictSet, restrictLaw,
   ifthenelse, gfp, relabel, relabelFun,
   substit, substitSimul,
@@ -127,22 +127,22 @@
 {-# NOINLINE restrictLaw #-}
 
 -- | Existential Quantification
-exists :: Int -> Bdd -> Bdd
-exists n b = withTwoBDDs bdd_Exist b (var n)
-{-# NOINLINE exists #-}
+exists_ :: Int -> Bdd -> Bdd
+exists_ n b = withTwoBDDs bdd_Exist b (var n)
+{-# NOINLINE exists_ #-}
 
 -- | Universal Quantification
-forall :: Int -> Bdd -> Bdd
-forall n b = withTwoBDDs bdd_Universal b (var n)
-{-# NOINLINE forall #-}
+forall_ :: Int -> Bdd -> Bdd
+forall_ n b = withTwoBDDs bdd_Universal b (var n)
+{-# NOINLINE forall_ #-}
 
 -- | Big Existential Quantification
 existsSet :: [Int] -> Bdd -> Bdd
-existsSet ns b = foldl (flip exists) b ns
+existsSet ns b = foldl (flip exists_) b ns
 
 -- | Big Universal Quantification
 forallSet :: [Int] -> Bdd -> Bdd
-forallSet ns b = foldl (flip forall) b ns
+forallSet ns b = foldl (flip forall_) b ns
 
 -- | True constant
 top :: Bdd
@@ -273,7 +273,9 @@
 allVarsOf b
   | b == bot = []
   | b == top = []
-  | otherwise = let (Just n) = firstVarOf b in n : nub (allVarsOf (thenOf b) ++ allVarsOf (elseOf b))
+  | otherwise =
+      let n = fromJust (firstVarOf b)
+      in n : nub (allVarsOf (thenOf b) ++ allVarsOf (elseOf b))
 
 -- | All variables in a given BDD, sorted, *not* lazy.
 allVarsOfSorted :: Bdd -> [Int]
@@ -308,7 +310,7 @@
 unravel b
   | b == bot = Bot
   | b == top = Top
-  | otherwise = Var n (unravel (thenOf b)) (unravel (elseOf b)) where (Just n) = firstVarOf b
+  | otherwise = Var n (unravel (thenOf b)) (unravel (elseOf b)) where n = fromJust $ firstVarOf b
 
 -- | Convert a tree to a BDD.
 ravel :: BddTree -> Bdd
@@ -330,7 +332,7 @@
   | b == bot = False
   | b == top = True
   | otherwise =
-      let (Just n) = firstVarOf b
+      let n = fromJust $ firstVarOf b
       in evaluateFun ((if f n then thenOf else elseOf) b) f
 
 -- | Get all satisfying assignments. These will be partial, i.e. only
@@ -341,7 +343,7 @@
   | b == top = [ [] ]
   | otherwise =
       [ (n,True):rest | rest <- allSats (thenOf b) ] ++ [ (n,False):rest | rest <- allSats (elseOf b) ]
-      where (Just n) = firstVarOf b
+      where n = fromJust $ firstVarOf b
 
 -- | Get the lexicographically smallest satisfying assignment, if there is any.
 anySat :: Bdd -> Maybe Assignment
@@ -350,8 +352,8 @@
   | b == top = Just []
   | otherwise = Just ((n,hastobetrue):rest) where
       hastobetrue = elseOf b == bot
-      (Just n)    = firstVarOf b
-      (Just rest) = if hastobetrue then anySat (thenOf b) else anySat (elseOf b)
+      n = fromJust $ firstVarOf b
+      rest = fromJust $ if hastobetrue then anySat (thenOf b) else anySat (elseOf b)
 
 -- | Given a set of all variables, complete an assignment.
 completeAss :: [Int] -> Assignment -> [Assignment]
@@ -375,7 +377,7 @@
   | b == top = 2 ^ length allvars
   | b == bot = 0
   | otherwise = (2 ^ length varsjumped) * posbelow where
-      (Just curvar) = firstVarOf b
+      curvar = fromJust $ firstVarOf b
       varsjumped = filter (< curvar) allvars
       varsleft   = filter (> curvar) allvars
       posbelow   = sum [satCountWith varsleft (branch b) | branch <- [thenOf,elseOf] ]
@@ -454,9 +456,9 @@
   , imp <$> smallerbdd <*> smallerbdd
   , equ <$> smallerbdd <*> smallerbdd
   , xor <$> smallerbdd <*> smallerbdd
-  , exists <$> randomvarnumber <*> smallerbdd
+  , exists_ <$> randomvarnumber <*> smallerbdd
   , existsSet <$> listOf randomvarnumber <*> smallerbdd
-  , forall <$> randomvarnumber <*> smallerbdd
+  , forall_ <$> randomvarnumber <*> smallerbdd
   , forallSet <$> listOf randomvarnumber <*> smallerbdd
   ]
   where
diff --git a/hs/Data/HasCacBDD/Visuals.hs b/hs/Data/HasCacBDD/Visuals.hs
--- a/hs/Data/HasCacBDD/Visuals.hs
+++ b/hs/Data/HasCacBDD/Visuals.hs
@@ -7,6 +7,7 @@
   svgGraph
 ) where
 
+import Data.Maybe (fromJust)
 import System.Exit
 import System.IO
 import System.Process
@@ -30,17 +31,17 @@
             let
               thisn = if null done then 0 else maximum (map snd done) + 1
               thisnstr = show thisn
-              (Just thisvar) = firstVarOf curB
+              thisvar = fromJust $ firstVarOf curB
               out1  = "n" ++ thisnstr ++ " [label=\"" ++ myShow thisvar ++ "\",shape=\"circle\"];\n"
               (lhs, rhs) = (thenOf curB, elseOf curB)
               (lhsoutput,lhsdone) = genGraphStep ((curB,thisn):done) lhs
-              (Just leftn) = lookup lhs lhsdone
+              leftn = fromJust $ lookup lhs lhsdone
               out2
                 | lhs == top = "n"++ thisnstr ++" -> Top;\n"
                 | lhs == bot = "n"++ thisnstr ++" -> Bot;\n"
                 | otherwise  = "n"++ thisnstr ++" -> n" ++ show leftn ++";\n" ++ lhsoutput
               (rhsoutput,rhsdone) = genGraphStep lhsdone rhs
-              (Just rightn) = lookup rhs rhsdone
+              rightn = fromJust $ lookup rhs rhsdone
               out3
                 | rhs == top = "n"++ thisnstr ++" -> Top [style=dashed];\n"
                 | rhs == bot = "n"++ thisnstr ++" -> Bot [style=dashed];\n"
diff --git a/stack.yaml b/stack.yaml
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,3 +1,3 @@
-resolver: lts-18.21
+resolver: lts-21.19
 packages:
 - '.'
diff --git a/tests/Main.hs b/tests/Main.hs
--- a/tests/Main.hs
+++ b/tests/Main.hs
@@ -23,7 +23,7 @@
       it "var 1 == var 1" $ var 1 `shouldBe` var 1
       it "imp (var 1) (var 1) == top" $ imp (var 1) (var 1) `shouldBe` top
       it "equ (var 1) (var 1) == top" $ equ (var 1) (var 1) `shouldBe` top
-      it "exists 1 (neg $ var 1) == top" $ exists 1 (neg $ var 1) `shouldBe` top
+      it "exists_ 1 (neg $ var 1) == top" $ exists_ 1 (neg $ var 1) `shouldBe` top
       it "gfp (\b -> con b (var 3)) == var 3" $ gfp (\b -> con b (var 3)) `shouldBe` var 3
       it "imp (conSet [var 1, var 0]) (var 1) == top" $ imp (conSet [var 1, var 0]) (var 1) `shouldBe` top
       it "imp (conSet [var 0, var 1]) (var 0) == top" $ imp (conSet [var 0, var 1]) (var 0) `shouldBe` top
@@ -35,7 +35,7 @@
       it "dis (var 1) (neg $ var 2) /= top" $ dis (var 1) (neg $ var 2) `shouldNotBe` top
       it "dis (var 1) (var 2) /= top" $ dis (var 1) (var 2) `shouldNotBe` top
       it "var 1 /= var 2" $ var 1 `shouldNotBe` var 2
-      it "forall 1 (var 1) /= top" $ forall 1 (var 1) `shouldNotBe` top
+      it "forall_ 1 (var 1) /= top" $ forall_ 1 (var 1) `shouldNotBe` top
     describe "Laws from de Morgan:" $ do
       it "dis to con" $ dis (neg $ var 1) (neg $ var 2) == neg (con (var 1) (var 2))
       it "con to dis" $ con (neg $ var 1) (neg $ var 2) == neg (dis (var 1) (var 2))
@@ -57,8 +57,8 @@
     it "var 3 == con (var 3) top" $ var 3 `shouldBe` con (var 3) top
     it "var 4 /= con (var 3) top" $ var 4 `shouldNotBe` con (var 3) top
     it "equ (var 1) (var 1) == top" $ equ (var 1) (var 1) `shouldBe` top
-    it "exists 1 (neg $ var 1) == top" $ exists 1 (neg $ var 1) `shouldBe` top
-    it "exists 1 (neg $ var 2) /= top" $ exists 1 (neg $ var 2) `shouldNotBe` top
+    it "exists_ 1 (neg $ var 1) == top" $ exists_ 1 (neg $ var 1) `shouldBe` top
+    it "exists_ 1 (neg $ var 2) /= top" $ exists_ 1 (neg $ var 2) `shouldNotBe` top
     it "gfp (\b -> con b (var 3)) == var 3" $ gfp (\b -> con b (var 3)) `shouldBe` var 3
     it "imp (conSet [var 1,var 0]) (var 1) == top" $ imp (conSet [var 1,var 0]) (var 1) `shouldBe` top
     it "imp (conSet [var 0,var 1]) (var 0) == top" $ imp (conSet [var 0,var 1]) (var 0) `shouldBe` top
@@ -82,7 +82,7 @@
     prop "conElim"        (\a b -> imp (con a b) a == top)
     prop "conElim3"       (\a b c -> imp (conSet [a, b, c]) a == top)
     prop "negNotEqual"    (\b -> neg b /= b)
-    prop "quantifDuality" (forAll (elements [0..maximumvar]) (\n b -> forall n b == neg (exists n (neg b))))
+    prop "quantifDuality" (forAll (elements [0..maximumvar]) (\n b -> forall_ n b == neg (exists_ n (neg b))))
     prop "allSats"        (\b -> all (\s -> restrictSet b s == top) (allSats b))
     prop "anySat"         (\b -> if b==bot then isNothing (anySat b) else restrictSet b (fromJust $ anySat b) == top)
     prop "ifthenelse"     (\a b c -> ifthenelse a b c == neg (dis (con a (neg b)) (con (neg a) (neg c))))