lean4-htt/src/Init/Data/Zero.lean
Sebastian Ullrich 09a5b34931
feat: make private the default in module (#9044)
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.
2025-06-28 16:30:53 +00:00

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/-
Copyright (c) 2021 Gabriel Ebner. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Gabriel Ebner, Mario Carneiro
-/
module
prelude
public import Init.Core
public section
/-!
Instances converting between `Zero α` and `OfNat α (nat_lit 0)`.
-/
instance (priority := 300) Zero.toOfNat0 {α} [Zero α] : OfNat α (nat_lit 0) where
ofNat := Zero α.1
instance (priority := 200) Zero.ofOfNat0 {α} [OfNat α (nat_lit 0)] : Zero α where
zero := 0
/-!
Instances converting between `One α` and `OfNat α (nat_lit 1)`.
-/
instance (priority := 300) One.toOfNat1 {α} [One α] : OfNat α (nat_lit 1) where
ofNat := One α.1
instance (priority := 200) One.ofOfNat1 {α} [OfNat α (nat_lit 1)] : One α where
one := 1
/--
The fundamental power operation in a monoid.
`npowRec n a = a*a*...*a` n times.
This function should not be used directly; it is often used to implement a `Pow M Nat` instance,
but end users should use the `a ^ n` notation instead.
-/
@[expose]
def npowRec [One M] [Mul M] : Nat → M → M
| 0, _ => 1
| n + 1, a => npowRec n a * a
/--
The fundamental scalar multiplication in an additive monoid.
`nsmulRec n a = a+a+...+a` n times.
This function should not be used directly;
it is often used to implement an instance for scalar multiplication.
-/
def nsmulRec [Zero M] [Add M] : Nat → M → M
| 0, _ => 0
| n + 1, a => nsmulRec n a + a