lean4-htt/library/init/list.lean
Sebastian Ullrich fd2c42a8bf chore(library, tests): switch to new attribute declaration syntax
sed -Ei 's/^(\s*)((private |protected )?(noncomputable )?(abbreviation|definition|meta_definition|theorem|lemma|proposition|corollary)\s+\S+\s*)((\s*\[(\S+(\s+[0-9]+)*|priority.*)\])+)\s*/\1attribute \6\n\1\2/' library/**/*.lean tests/**/*.lean
sed -Ei 's/\s+$//' library/**/*.lean  # remove trailing whitespace
2016-08-12 15:36:12 -07:00

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/-
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
-/
prelude
import init.logic init.nat
open decidable list
attribute [instance]
protected definition list.is_inhabited (A : Type) : inhabited (list A) :=
inhabited.mk list.nil
notation h :: t := cons h t
notation `[` l:(foldr `, ` (h t, cons h t) nil `]`) := l
namespace list
variable {A : Type}
definition append : list A → list A → list A
| [] l := l
| (h :: s) t := h :: (append s t)
definition length : list A → nat
| [] := 0
| (a :: l) := length l + 1
open option nat
definition nth : list A → nat → option A
| [] _ := none
| (a :: l) 0 := some a
| (a :: l) (n+1) := nth l n
definition head {A : Type} [inhabited A] : list A → A
| [] := default A
| (a :: l) := a
definition tail : list A → list A
| [] := []
| (a :: l) := l
definition concat : Π (x : A), list A → list A
| a [] := [a]
| a (b :: l) := b :: concat a l
definition reverse : list A → list A
| [] := []
| (a :: l) := concat a (reverse l)
definition map {B : Type} (f : A → B) : list A → list B
| [] := []
| (a :: l) := f a :: map l
definition join : list (list A) → list A
| [] := []
| (l :: ls) := append l (join ls)
definition filter (p : A → Prop) [h : decidable_pred p] : list A → list A
| [] := []
| (a::l) := if p a then a :: filter l else filter l
definition dropn : → list A → list A
| 0 a := a
| (succ n) [] := []
| (succ n) (x::r) := dropn n r
end list
attribute [instance]
definition list_has_append {A : Type} : has_append (list A) :=
has_append.mk list.append