34 lines
840 B
Text
34 lines
840 B
Text
#lang lean4
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import Std
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def check (x : IO Nat) (expected : IO Nat) : IO Unit := do
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unless (← x) == (← expected) do
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throw $ IO.userError "unexpected result"
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def f1 (xs : Std.PArray Nat) (top : 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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if x % 2 == 0 then
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IO.println s!"x: {x}"
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sum := sum + x
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if sum > top then
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return sum
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IO.println s!"sum: {sum}"
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return sum
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#eval f1 [1, 2, 3, 4, 5, 10, 20].toPersistentArray 10
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#eval check (f1 [1, 2, 3, 4, 5, 10, 20].toPersistentArray 10) (pure 16)
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def f2 (xs : Std.PArray Nat) (top : 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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if x % 2 == 0 then
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IO.println s!"x: {x}"
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sum := sum + x
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if sum > top then
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break
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IO.println s!"sum: {sum}"
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return sum
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#eval check (f1 (List.iota 100).toPersistentArray 1000) (f2 (List.iota 100).toPersistentArray 1000)
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