65 lines
1.5 KiB
Text
65 lines
1.5 KiB
Text
def f (v : Nat) : StateRefT Nat IO Nat := do
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IO.println "hello"
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modify fun s => s - v
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get
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def g : IO Nat :=
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f 5 |>.run' 20
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#eval (f 5).run' 20
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#eval (do set 100; f 5 : StateRefT Nat IO Nat).run' 0
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def f2 : ReaderT Nat (StateRefT Nat IO) Nat := do
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let v ← read
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IO.println $ "context " ++ toString v
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modify fun s => s + v
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get
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#eval (f2.run 10).run' 20
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def f3 : StateT String (StateRefT Nat IO) Nat := do
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let s ← get
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let n ← getThe Nat
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set $ s ++ ", " ++ toString n
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let s ← get
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IO.println s
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set (n+1)
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getThe Nat
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#eval (f3.run' "test").run' 10
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structure Label {β : Type} (v : β) (α : Type) :=
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(val : α)
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class HasGetAt {β : Type} (v : β) (α : outParam Type) (m : Type → Type) :=
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(getAt : m α)
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instance monadState.hasGetAt (β : Type) (v : β) (α : Type) (m : Type → Type) [Monad m] [MonadStateOf (Label v α) m] : HasGetAt v α m :=
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{ getAt := do let a ← getThe (Label v α); pure a.val }
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export HasGetAt (getAt)
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abbrev M := StateRefT (Label 0 Nat) $ StateRefT (Label 1 Nat) $ StateRefT (Label 2 Nat) IO
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def f4 : M Nat := do
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let a0 : Nat ← getAt 0
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let a1 ← getAt 1
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let a2 ← getAt 2
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IO.println $ "state0 " ++ toString a0
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IO.println $ "state1 " ++ toString a1
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IO.println $ "state1 " ++ toString a2
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pure (a0 + a1 + a2)
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#eval f4.run' ⟨10⟩ |>.run' ⟨20⟩ |>.run' ⟨30⟩
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abbrev S (ω : Type) := StateRefT Nat $ StateRefT String $ ST ω
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def f5 {ω} : S ω Unit := do
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let s ← getThe String
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modify fun n => n + s.length
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pure ()
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def f5Pure (n : Nat) (s : String) :=
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runST fun _ => f5.run n |>.run s
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#eval f5Pure 10 "hello world"
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