mathlib documentation

core.data.dlist

structure dlist  :
Type uType u

A difference list is a function that, given a list, returns the original contents of the difference list prepended to the given list.

This structure supports O(1) append and concat operations on lists, making it useful for append-heavy uses such as logging and pretty printing.

def dlist.of_list {α : Type u} :
list αdlist α

Convert a list to a dlist

Equations
def dlist.lazy_of_list {α : Type u} :
thunk (list α)dlist α

Convert a lazily-evaluated list to a dlist

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def dlist.to_list {α : Type u} :
dlist αlist α

Convert a dlist to a list

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def dlist.empty {α : Type u} :

Create a dlist containing no elements

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def dlist.singleton {α : Type u} :
α → dlist α

Create dlist with a single element

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def dlist.cons {α : Type u} :
α → dlist αdlist α

O(1) Prepend a single element to a dlist

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def dlist.concat {α : Type u} :
α → dlist αdlist α

O(1) Append a single element to a dlist

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def dlist.append {α : Type u} :
dlist αdlist αdlist α

O(1) Append dlists

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@[instance]
def dlist.has_append {α : Type u} :

Equations
theorem dlist.to_list_of_list {α : Type u} (l : list α) :

theorem dlist.of_list_to_list {α : Type u} (l : dlist α) :

theorem dlist.to_list_singleton {α : Type u} (x : α) :

theorem dlist.to_list_append {α : Type u} (l₁ l₂ : dlist α) :
(l₁ ++ l₂).to_list = l₁.to_list ++ l₂.to_list

theorem dlist.to_list_cons {α : Type u} (x : α) (l : dlist α) :

theorem dlist.to_list_concat {α : Type u} (x : α) (l : dlist α) :