06ad52575a
After this commit, we have to use an explicit `discard` in code such as ``` def g (x : Nat) : IO Nat := ... def f (x : Nat) : IO Unit := do discard <| g x -- type error without the `discard` IO.println x ``` Motivation: prevent users from making mistakes such as ``` def f (xs : Array Nat) : IO Unit := do xs.set! 0 1 IO.println xs ``` when they meant to write ``` def f (xs : Array Nat) : IO Unit := do let xs := xs.set! 0 1 IO.println xs ```
36 lines
922 B
Text
36 lines
922 B
Text
#lang lean4
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#eval id (α := IO _) do
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let t1 ← IO.asTask $ Nat.forM 10 fun _ => IO.println "hi";
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let t2 ← IO.asTask $ Nat.forM 10 fun _ => IO.println "ho";
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IO.ofExcept t1.get
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#eval id (α := IO _) do
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let t1 ← IO.mapTask IO.println (Task.spawn fun _ => "ha");
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pure ()
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#eval id (α := IO _) do
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let t1 ← IO.bindTask (Task.spawn fun _ => "hu") fun s =>
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IO.asTask (IO.println s);
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pure ()
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#eval id (α := IO _) do
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let t1 ← IO.asTask do {
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let c ← IO.checkCanceled;
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IO.println (if c then "canceled!" else "done!")
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};
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pure ()
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#eval id (α := IO _) do
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let t1 ← IO.asTask do {
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let c ← IO.checkCanceled;
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IO.println (if c then "canceled! 2" else "done! 2")
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};
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IO.cancel t1;
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discard $ IO.wait t1;
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pure ()
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#eval IO.waitAny [
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Task.spawn fun _ => dbgSleep 2 fun _ => "A",
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Task.spawn fun _ => dbgSleep 3 fun _ => "B",
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Task.spawn fun _ => dbgSleep 1 fun _ => "C"
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]
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