lean4-htt/tests/bench/mergeSort/Bench.lean
Kim Morrison 4aa74d9c0b
feat: List.mergeSort (#5092)
Defines `mergeSort`, a naive stable merge sort algorithm, replaces it
via a `@[csimp]` lemma with something faster at runtime, and proves the
following results:

* `mergeSort_sorted`: `mergeSort` produces a sorted list.
* `mergeSort_perm`: `mergeSort` is a permutation of the input list.
* `mergeSort_of_sorted`: `mergeSort` does not change a sorted list.
* `mergeSort_cons`: proves `mergeSort le (x :: xs) = l₁ ++ x :: l₂` for
some `l₁, l₂`
so that `mergeSort le xs = l₁ ++ l₂`, and no `a ∈ l₁` satisfies `le a
x`.
* `mergeSort_stable`: if `c` is a sorted sublist of `l`, then `c` is
still a sublist of `mergeSort le l`.
2024-08-20 06:32:52 +00:00

18 lines
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Text

open List.MergeSort.Internal
def main (args : List String) : IO Unit := do
let k := 5
let some arg := args[0]? | throw <| IO.userError s!"specify length of test data in multiples of 10^{k}"
let some i := arg.toNat? | throw <| IO.userError s!"specify length of test data in multiples of 10^{k}"
let n := i * (10^k)
let i₁ := List.iota n
let i₂ := List.range n
let i₃ ← (List.range n).mapM (fun _ => IO.rand 0 1000)
let i₄ := (List.range (i * (10^(k-3)))).bind (fun k => (k * 1000 + 1) :: (k * 1000) :: List.range' (k * 1000 + 2) 998)
let start ← IO.monoMsNow
let o₁ := (mergeSortTR₂ (· ≤ ·) i₁).length == n
let o₂ := (mergeSortTR₂ (· ≤ ·) i₂).length == n
let o₃ := (mergeSortTR₂ (· ≤ ·) i₃).length == n
let o₄ := (mergeSortTR₂ (· ≤ ·) i₄).length == n
IO.println (((← IO.monoMsNow) - start)/4)
IO.Process.exit (if o₁ && o₂ && o₃ && o₄ then 0 else 1)