09a5b34931
This PR adjusts the experimental module system to make `private` the default visibility modifier in `module`s, introducing `public` as a new modifier instead. `public section` can be used to revert the default for an entire section, though this is more intended to ease gradual adoption of the new semantics such as in `Init` (and soon `Std`) where they should be replaced by a future decl-by-decl re-review of visibilities.
38 lines
1.2 KiB
Text
38 lines
1.2 KiB
Text
/-
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Copyright (c) 2024 Lean FRO. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Kim Morrison
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-/
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module
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prelude
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public import Init.Data.Array.Basic
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public import Init.Data.Nat.Lemmas
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public import Init.Data.Range
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public section
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set_option linter.listVariables true -- Enforce naming conventions for `List`/`Array`/`Vector` variables.
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set_option linter.indexVariables true -- Enforce naming conventions for index variables.
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namespace Array
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/--
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Compares arrays lexicographically with respect to a comparison `lt` on their elements.
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Specifically, `Array.lex as bs lt` is true if
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* `bs` is larger than `as` and `as` is pairwise equivalent via `==` to the initial segment of `bs`,
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or
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* there is an index `i` such that `lt as[i] bs[i]`, and for all `j < i`, `as[j] == bs[j]`.
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-/
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def lex [BEq α] (as bs : Array α) (lt : α → α → Bool := by exact (· < ·)) : Bool := Id.run do
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for h : i in [0 : min as.size bs.size] do
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-- TODO: `omega` should be able to find this itself.
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have : i < min as.size bs.size := Membership.get_elem_helper h rfl
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if lt as[i] bs[i] then
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return true
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else if as[i] != bs[i] then
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return false
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return as.size < bs.size
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end Array
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