diff --git a/tests/playground/task_test.lean b/tests/playground/task_test.lean
index 06b85d2457..383091ad5d 100644
--- a/tests/playground/task_test.lean
+++ b/tests/playground/task_test.lean
@@ -1,20 +1,20 @@
 def g (x : Nat) : Nat :=
-dbgTrace ("g: " ++ toString x) $ λ _,
+dbgTrace ("g: " ++ toString x) $ fun _ =>
   x + 1
 
 def f1 (x : Nat) : Nat :=
-dbgSleep 1000 $ λ _,
-dbgTrace ("f1: " ++ toString x) $ λ _,
+dbgSleep 1000 $ fun _ =>
+dbgTrace ("f1: " ++ toString x) $ fun _ =>
   g (x + 1)
 
 def f2 (x : Nat) : Nat :=
-dbgSleep 100 $ λ _,
-dbgTrace ("f2: " ++ toString x) $ λ _,
+dbgSleep 100 $ fun _ =>
+dbgTrace ("f2: " ++ toString x) $ fun  _ =>
   g x
 
 def main (xs : List String) : IO UInt32 :=
-let t1 := Task.mk $ (λ _, f1 xs.head.toNat) in
-let t2 := Task.mk $ (λ _, f2 xs.head.toNat) in
-dbgSleep 1000 $ λ _,
+let t1 := Task.mk $ (fun _ => f1 xs.head.toNat) in
+let t2 := Task.mk $ (fun _ => f2 xs.head.toNat) in
+dbgSleep 1000 $ fun _ =>
 IO.println (toString t1.get ++ " " ++ toString t2.get) *>
 pure 0
diff --git a/tests/playground/task_test2.lean b/tests/playground/task_test2.lean
index a97e1bca7c..d5e26e1ae5 100644
--- a/tests/playground/task_test2.lean
+++ b/tests/playground/task_test2.lean
@@ -1,12 +1,12 @@
 def run1 (i : Nat) (n : Nat) (xs : List Nat) : Nat :=
-n.repeat (λ r,
-  dbgTrace (">> [" ++ toString i ++ "] " ++ toString r) $ λ _,
-  xs.foldl (+) r)
+n.repeat (fun r =>
+  dbgTrace (">> [" ++ toString i ++ "] " ++ toString r) $ fun _ =>
+  xs.foldl (fun a b => a + b) r)
 0
 
 def main (xs : List String) : IO UInt32 :=
 let ys := (List.replicate xs.head.toNat 1) in
-let ts : List (Task Nat) := (List.iota 10).map (λ i, Task.mk $ λ _, run1 (i+1) xs.head.toNat ys) in
+let ts : List (Task Nat) := (List.iota 10).map (fun i => Task.mk $ fun _ => run1 (i+1) xs.head.toNat ys) in
 let ns : List Nat := ts.map Task.get in
 IO.println (">> " ++ toString ns) *>
 pure 0
diff --git a/tests/playground/task_test3.lean b/tests/playground/task_test3.lean
index 8eb5b23a79..a3efb5ccc0 100644
--- a/tests/playground/task_test3.lean
+++ b/tests/playground/task_test3.lean
@@ -1,12 +1,12 @@
 def run1 (i : Nat) (n : Nat) (xs : List Nat) : Nat :=
-n.repeat (λ r,
+n.repeat (fun r =>
   -- dbgTrace (">> [" ++ toString i ++ "] " ++ toString r) $ λ _,
-  xs.foldl (+) (r+i))
+  xs.foldl (fun a b => a + b) (r+i))
 0
 
 def main (xs : List String) : IO UInt32 :=
 let ys := (List.replicate xs.head.toNat 1) in
-let ts : List (Task Nat) := (List.iota 10).map (λ i, Task.mk $ λ _, run1 (i+1) xs.head.toNat ys) in
+let ts : List (Task Nat) := (List.iota 10).map (fun i => Task.mk $ fun _ => run1 (i+1) xs.head.toNat ys) in
 let ns : List Nat := ts.map Task.get in
 IO.println (">> " ++ toString ns) *>
 pure 0
diff --git a/tests/playground/task_test4.lean b/tests/playground/task_test4.lean
index 3edc298630..46b53a7db7 100644
--- a/tests/playground/task_test4.lean
+++ b/tests/playground/task_test4.lean
@@ -1,12 +1,12 @@
 def run1 (i : Nat) (n : Nat) (xs : List Nat) : Nat :=
-n.repeat (λ r,
+n.repeat (fun r =>
   let s := (">> [" ++ toString i ++ "] " ++ toString r) in
-  xs.foldl (+) (r + s.length))
+  xs.foldl (fun a b => a + b) (r + s.length))
 0
 
 def main (xs : List String) : IO UInt32 :=
 let ys := (List.replicate xs.head.toNat 1) in
-let ts : List (Task Nat) := (List.iota 10).map (λ i, Task.mk $ λ _, run1 (i+1) xs.head.toNat ys) in
+let ts : List (Task Nat) := (List.iota 10).map (fun i => Task.mk $ fun _ => run1 (i+1) xs.head.toNat ys) in
 let ns : List Nat := ts.map Task.get in
 IO.println (">> " ++ toString ns) *>
 pure 0