lean4-htt/tests/lean/ref1.lean

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Text

def inc (r : IO.Ref Nat) : IO Unit :=
do v ← r.get;
r.set (v+1);
IO.println (">> " ++ toString v)
def initArray (r : IO.Ref (Array Nat)) (n : Nat) : IO Unit :=
n.mfor $ fun i => do
r.modify $ fun a => a.push (2*i)
def showArrayRef (r : IO.Ref (Array Nat)) : IO Unit :=
do a ← r.swap ∅;
a.size.mfor (fun i => IO.println ("[" ++ toString i ++ "]: " ++ toString (a.get! i)));
r.swap a;
pure ()
def tst (n : Nat) : IO Unit :=
do r₁ ← IO.mkRef 0;
n.mfor $ λ _ => inc r₁;
r₂ ← IO.mkRef (∅ : Array Nat);
initArray r₂ n;
showArrayRef r₂
#eval tst 10