483f32edd8
This feature produced counterintuitive behavior and confused users. See discussion at #770. As pointed out by @tydeu, it is not too much work to write `Id.run <|` before the `do` when we want to use the `do` notation in pure code. closes #770
71 lines
1.8 KiB
Text
71 lines
1.8 KiB
Text
--
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def f1 (x : Nat) : IO Nat := do
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y := 1 -- error 'y' cannot be reassigned
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def f2 (xs : List (Nat × Nat)) : List (Nat × Nat) := Id.run <| do
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for (x, y) in xs do
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(y, x) := (x, y) -- error 'y' (and 'x') cannot be reassigned
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def f3 (xs : List (Nat × Nat)) : List (Nat × Nat) := Id.run <| do
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for p in xs do
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p := (p.2, p.1) -- works. `forInMap` requires a variable
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inductive Vector (α : Type) : Nat → Type
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| nil : Vector α 0
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| cons : α → {n : Nat} → Vector α n → Vector α (n+1)
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def f4 (b : Bool) (n : Nat) (v : Vector Nat n) : Vector Nat (n+1) := Id.run <| do
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let mut v := v
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if b then
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v := Vector.cons 1 v
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Vector.cons 1 v
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def f5 (y : Nat) (xs : List Nat) : List Bool := Id.run <| do
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let mut y := y
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for x in xs do
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y := true -- invalid reassigned
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def f6 (xs : List Nat) : IO (List Nat) := do
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for x in xs do -- type error
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IO.println x
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def f7 (xs : List Nat) : IO Unit := do
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unless xs.isEmpty do
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break -- error must be inside 'for'
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def f8 (xs : List Nat) : IO Unit := do
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unless xs.isEmpty do
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continue -- error must be inside 'for'
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def f9 (xs : List Nat) : IO Unit := do
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return xs -- error, must be last element in the sequence
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return xs
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def f10 (x : Nat) : IO Unit := do
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IO.println x
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#print f10 -- we do not generate an unnecessary bind
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def f11 (x : Nat) : IO Unit := do
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if x > 0 then
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IO.println "x is not zero"
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IO.mkRef true -- error here as expected
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def f12 (x : Nat) : IO Unit := do
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let mut x := x
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if x > 0 then
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pure true
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else
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x := x + 1
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IO.println "hello" -- error here the other branch returns `Bool`
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IO.println x
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def f13 (xs : List Nat) : IO Bool := do
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if xs == [] then
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return true
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else
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return false
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IO.println "hello" -- error unreachable
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def f14 (x : Nat) : IO Nat := do
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let y ← if x == 0 then return 100 else return 200
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IO.println ("y: " ++ toString y) -- error unreachable
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return 0
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