72 lines
1.3 KiB
Text
72 lines
1.3 KiB
Text
abbrev M := StateRefT Nat IO
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def testM {α} [ToString α] [BEq 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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let v ←
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try
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dec x
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return x
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catch _ =>
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return 1
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def f2 (xs : List Nat) : M Nat := do
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let mut sum := 0
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for x in xs do
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try
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dec x
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sum := sum + x
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if sum > 100 then
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break
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continue
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catch _ =>
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break
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return sum
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#eval testM 100 6 $ f2 [1, 2, 3]
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#eval testM 200 101 $ f2 [1, 100, 200, 300]
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#eval testM 1 1 $ f2 [1, 100, 200, 300]
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def f3 (xs : List Nat) : M Nat := do
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let mut sum := 0
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for x in xs do
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try
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dec x
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sum := sum + x
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if sum > 100 then
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return sum
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continue
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catch _ =>
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return sum
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return sum
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#eval testM 100 6 $ f3 [1, 2, 3]
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#eval testM 200 101 $ f3 [1, 100, 200, 300]
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#eval testM 1 1 $ f3 [1, 100, 200, 300]
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def f4 (xs : Array Nat) : IO Nat := do
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let mut sum := 0
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for x in xs do
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sum := sum + x
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IO.println x
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return sum
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#eval f4 #[1, 2, 3]
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def f5 (xs : Array Nat) : IO Nat := do
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let mut sum := 0
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for x in xs[1 : xs.size - 1] do
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sum := sum + x
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IO.println x
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return sum
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#eval f5 #[1, 2, 3, 4, 5, 6]
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