diff --git a/a1/src/APL/AST.hs b/a1/src/APL/AST.hs
index 2f4c316..9172de6 100644
--- a/a1/src/APL/AST.hs
+++ b/a1/src/APL/AST.hs
@@ -25,4 +25,17 @@ data Exp
   deriving (Eq, Show)
 
 printExp :: Exp -> String
-printExp = undefined -- TODO
+printExp (CstBool b)      = show b
+printExp (CstInt i)       = show i
+printExp (Add e1 e2)      = "("++(printExp e1)++" + "++(printExp e2)++")"
+printExp (Mul e1 e2)      = "("++(printExp e1)++" * "++(printExp e2)++")"
+printExp (Sub e1 e2)      = "("++(printExp e1)++" - "++(printExp e2)++")"
+printExp (Div e1 e2)      = "("++(printExp e1)++" / "++(printExp e2)++")"
+printExp (Pow e1 e2)      = "("++(printExp e1)++" ** "++(printExp e2)++")"
+printExp (If e1 e2 e3)    = "(if "++(printExp e1)++" then "++(printExp e2)++" else "++(printExp e3)++")"
+printExp (Var var)        = var
+printExp (Let var e1 e2)  = "(let "++var++" = "++(printExp e1)++" in "++(printExp e2)++")"
+printExp (Lambda var e)   = "(\\"++var++" -> "++(printExp e)++")"
+printExp (Apply e1 e2)    = "("++(printExp e1)++" "++(printExp e2)++")"
+printExp (TryCatch e1 e2) = "(try "++(printExp e1)++" catch "++(printExp e2)++")"
+printExp _ = "error"
diff --git a/a1/src/APL/AST_Tests.hs b/a1/src/APL/AST_Tests.hs
index 826229e..82d953a 100644
--- a/a1/src/APL/AST_Tests.hs
+++ b/a1/src/APL/AST_Tests.hs
@@ -1,11 +1,44 @@
 module APL.AST_Tests (tests) where
 
--- import APL.AST (Exp (..))
+import APL.AST (Exp (..), printExp)
 import Test.Tasty (TestTree, testGroup)
--- import Test.Tasty.HUnit (testCase, (@?=))
+import Test.Tasty.HUnit (testCase, (@?=))
 
 tests :: TestTree
 tests =
   testGroup
     "Prettyprinting"
-    []
+    [
+      testCase "CstBool" $
+        printExp (CstBool True) @?= "True",
+      testCase "CstInt" $
+        printExp (CstInt 500) @?= "500",
+      testCase "Add" $
+        printExp (Add (CstInt 1) (CstInt 9999)) @?= "(1 + 9999)",
+      testCase "Mul" $
+        printExp (Mul (CstInt 1) (CstInt 9999)) @?= "(1 * 9999)",
+      testCase "Sub" $
+        printExp (Sub (CstInt 1) (CstInt 9999)) @?= "(1 - 9999)",
+      testCase "Div" $
+        printExp (Div (CstInt 1) (CstInt 9999)) @?= "(1 / 9999)",
+      testCase "Pow" $
+        printExp (Pow (CstInt 1) (CstInt 9999)) @?= "(1 ** 9999)",
+      testCase "If" $
+        printExp (If (CstBool True) (CstInt 2) (CstInt 3))
+        @?= "(if True then 2 else 3)",
+      testCase "Var" $
+        printExp (Var "missing")
+        @?= "missing",
+      testCase "Let" $
+        printExp (Let "x" (CstInt 2) (Var "x"))
+        @?= "(let x = 2 in x)",
+      testCase "Lambda" $
+        printExp (Lambda "x" (Var "x"))
+        @?= "(\\x -> x)",
+      testCase "Apply" $
+        printExp (Apply (Lambda "x" (Var "x")) (CstInt 1))
+        @?= "((\\x -> x) 1)",
+      testCase "TryCatch" $
+        printExp (TryCatch (CstInt 0) (CstInt 1))
+        @?= "(try 0 catch 1)"
+    ]