4eefc41b6e
We want to make sure string users do not depend on the string implementation. This is the first step. We need this refactoring *now* to make sure it will not be super painful to address issue #1175
21 lines
975 B
Text
21 lines
975 B
Text
/-
|
|
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.meta
|
|
|
|
namespace string
|
|
lemma empty_ne_str (c : char) (s : string) : empty ≠ str s c :=
|
|
begin cases s, unfold str empty, intro h, injection h, contradiction end
|
|
|
|
lemma str_ne_empty (c : char) (s : string) : str s c ≠ empty :=
|
|
begin cases s, unfold str empty, intro h, injection h, contradiction end
|
|
|
|
lemma str_ne_str_left {c₁ c₂ : char} (s₁ s₂ : string) : c₁ ≠ c₂ → str s₁ c₁ ≠ str s₂ c₂ :=
|
|
begin cases s₁, cases s₂, intros h₁ h₂, unfold str at h₂, injection h₂, injection h, contradiction end
|
|
|
|
lemma str_ne_str_right (c₁ c₂ : char) {s₁ s₂ : string} : s₁ ≠ s₂ → str s₁ c₁ ≠ str s₂ c₂ :=
|
|
begin cases s₁, cases s₂, intros h₁ h₂, unfold str at h₂, injection h₂, injection h, subst data, contradiction end
|
|
end string
|