max/lean4-htt
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 2

doc: docstrings for List.isPrefixOf

Browse source
This commit is contained in:
E.W.Ayers 2022-06-09 15:38:48 -04:00 • committed by Leonardo de Moura
parent 0707e4d442
commit a7c33a963f
2 changed files with 6 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
src/Init/Data/Array/Basic.lean
View file

@ -765,7 +765,8 @@ def isPrefixOfAux [BEq α] (as bs : Array α) (hle : as.size ≤ bs.size) (i : N
true
termination_by _ => as.size - i
/- Return true iff `as` is a prefix of `bs` -/
/-- Return true iff `as` is a prefix of `bs`.
That is, `bs = as ++ t` for some `t : List α`.-/
def isPrefixOf [BEq α] (as bs : Array α) : Bool :=
if h : as.size ≤ bs.size then
isPrefixOfAux as bs h 0

6
src/Init/Data/List/Basic.lean
View file

@ -423,13 +423,15 @@ instance [LT α] : LE (List α) := ⟨List.le⟩
instance [LT α] [DecidableRel ((· < ·) : α → α → Prop)] : (l₁ l₂ : List α) → Decidable (l₁ ≤ l₂) :=
fun _ _ => inferInstanceAs (Decidable (Not _))
/-- `isPrefixOf l₁ l₂` returns `true` Iff `l₁` is a prefix of `l₂`. -/
/-- `isPrefixOf l₁ l₂` returns `true` Iff `l₁` is a prefix of `l₂`.
That is, there exists a `t` such that `l₂ == l₁ ++ t`. -/
def isPrefixOf [BEq α] : List α → List α → Bool
| [], _ => true
| _, [] => false
| a::as, b::bs => a == b && isPrefixOf as bs
/-- `isSuffixOf l₁ l₂` returns `true` Iff `l₁` is a suffix of `l₂`. -/
/-- `isSuffixOf l₁ l₂` returns `true` Iff `l₁` is a suffix of `l₂`.
That is, there exists a `t` such that `l₂ == t ++ l₁`. -/
def isSuffixOf [BEq α] (l₁ l₂ : List α) : Bool :=
isPrefixOf l₁.reverse l₂.reverse