f4ee72b18c
This PR introduces a very minimal version of the new iterator library. It comes with list iterators and various consumers, namely `toArray`, `toList`, `toListRev`, `ForIn`, `fold`, `foldM` and `drain`. All consumers also come in a partial variant that can be used without any proofs. This limited version of the iterator library generates decent code, even with the old code generator.
67 lines
1.3 KiB
Text
67 lines
1.3 KiB
Text
import Std.Data.Iterators
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section ListIteratorBasic
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/-- info: [1, 2, 3].iter : Std.Iter Nat -/
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#guard_msgs in
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#check [1, 2, 3].iter
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/-- info: [1, 2, 3].iterM Id : Std.IterM Id Nat -/
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#guard_msgs in
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#check [1, 2, 3].iterM Id
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/-- info: [1, 2, 3] -/
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#guard_msgs in
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#eval [1, 2, 3].iter.toList
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/-- info: #[1, 2, 3] -/
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#guard_msgs in
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#eval [1, 2, 3].iter.toArray
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/-- info: [1, 2, 3] -/
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#guard_msgs in
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#eval [1, 2, 3].iter |>.allowNontermination.toList
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/-- info: ([1, 2, 3].iterM IO).toList : IO (List Nat) -/
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#guard_msgs in
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#check [1, 2, 3].iterM IO |>.toList
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/-- info: [1, 2, 3] -/
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#guard_msgs in
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#eval [1, 2, 3].iterM IO |>.toList
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/-- info: #[1, 2, 3] -/
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#guard_msgs in
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#eval [1, 2, 3].iterM IO |>.toArray
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end ListIteratorBasic
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section WellFoundedRecursion
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def sum (l : List Nat) : Nat :=
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go l.iter 0
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where
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@[specialize] -- The old code generator seems to need this.
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go it acc :=
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match it.step with
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| .yield it' out _ => go it' (acc + out)
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| .skip it' _ => go it' acc
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| .done _ => acc
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termination_by it.finitelyManySteps
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/-- info: 6 -/
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#guard_msgs in
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#eval sum [1, 2, 3]
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end WellFoundedRecursion
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section Loop
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def sumFold (l : List Nat) : Nat :=
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l.iter.fold (init := 0) (· + ·)
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/-- info: 6 -/
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#guard_msgs in
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#eval [1, 2, 3].iter.fold (init := 0) (· + · )
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end Loop
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