8a6cb1842f
@Kha I did not implement support for reassignments and `continue`, `break`, `return` inside the `finally` clause. It is doable, but it feels like unnecessary complexity. We currently don't have any instance in our code base where this would be useful.
83 lines
1.4 KiB
Text
83 lines
1.4 KiB
Text
new_frontend
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abbrev M := StateRefT Nat IO
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def testM {α} [HasToString α] [HasBeq α] (init : Nat) (expected : α) (x : M α): IO Unit := do
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let v ← x.run' init
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IO.println ("result " ++ toString v)
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unless v == expected do
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throw $ IO.userError "unexpected"
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def dec (x : Nat) : M Unit := do
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if (← get) == 0 then
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throw $ IO.userError "value is zero"
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modify (· - x)
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def f1 (x : Nat) : M Nat := do
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try
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dec x
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dec x
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get
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catch _ =>
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pure 1000
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finally
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IO.println "done"
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#eval testM 10 8 $ f1 1
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#eval testM 1 1000 $ f1 1
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def f2 (x : Nat) : M Nat := do
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try
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if x > 100 then
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return x
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dec x
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pure (← get)
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catch _ =>
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pure 1000
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finally
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IO.println "done"
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#eval testM 0 500 $ f2 500
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#eval testM 0 1000 $ f2 50
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#eval testM 200 150 $ f2 50
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def f3 (x : Nat) : M Nat := do
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try
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dec x
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pure (← get)
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catch
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| IO.Error.userError err => IO.println err; pure 2000
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| ex => throw ex
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#eval testM 0 2000 $ f3 10
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def f4 (xs : List Nat) : M Nat := do
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let y := 0
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for x in xs do
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IO.println ("x: " ++ toString x)
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try
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dec x
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y := y + x
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catch _ =>
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set y
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break
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get
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#eval testM 5 6 $ f4 [1, 2, 3, 4, 5, 6]
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#eval testM 40 19 $ f4 [1, 2, 3, 4, 5, 6]
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def f5 (xs : List Nat) : M Nat := do
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let y := 0
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for x in xs do
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IO.println ("x: " ++ toString x)
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try
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dec x
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y := y + x
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catch _ =>
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return y
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IO.println "after for"
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modify (· - 1)
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get
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#eval testM 5 6 $ f5 [1, 2, 3, 4, 5, 6]
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#eval testM 40 18 $ f5 [1, 2, 3, 4, 5, 6]
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