A list with a head and a tail, where the tail can be empty.
class val Cons[A: A] is ReadSeq[val->A] box
new val create( a: val->A, t: (Cons[A] val | Nil[A] val)) : Cons[A] val^
Returns the size of the list.
fun box size() : USize val
Returns the i-th element of the list. Errors if the index is out of bounds.
fun box apply( i: USize val) : val->A ?
Returns an iterator over the elements of the list.
fun box values() : Iterator[val->A] ref^
Returns a Bool indicating if the list is empty.
fun box is_empty() : Bool val
Returns a Bool indicating if the list is non-empty.
fun box is_non_empty() : Bool val
Returns the head of the list.
fun box head() : val->A
Returns the tail of the list.
fun box tail() : (Cons[A] val | Nil[A] val)
Builds a new list by reversing the elements in the list.
fun val reverse() : (Cons[A] val | Nil[A] val)
Builds a new list with an element added to the front of this list.
fun val prepend( a: val->A!) : Cons[A] val
Builds a new list that is the concatenation of this list and the provided list.
fun val concat( l: (Cons[A] val | Nil[A] val)) : (Cons[A] val | Nil[A] val)
Builds a new list by applying a function to every member of the list.
fun val map[B: B](
f: {(val->A): val->B}[A, B] box)
: (Cons[B] val | Nil[B] val)
Builds a new list by applying a function to every member of the list and using the elements of the resulting lists.
fun val flat_map[B: B](
f: {(val->A): List[B]}[A, B] box)
: (Cons[B] val | Nil[B] val)
Applies the supplied function to every element of the list in order.
fun val for_each(
f: {(val->A)}[A] box)
: None val
Builds a new list with those elements that satisfy a provided predicate.
fun val filter(
f: {(val->A): Bool}[A] box)
: (Cons[A] val | Nil[A] val)
Folds the elements of the list using the supplied function.
fun val fold[B: B](
f: {(B, val->A): B^}[A, B] box,
acc: B)
: B
Returns true if every element satisfies the provided predicate, false otherwise.
fun val every(
f: {(val->A): Bool}[A] box)
: Bool val
Returns true if at least one element satisfies the provided predicate, false otherwise.
fun val exists(
f: {(val->A): Bool}[A] box)
: Bool val
Builds a pair of lists, the first of which is made up of the elements satisfying the supplied predicate and the second of which is made up of those that do not.
fun val partition(
f: {(val->A): Bool}[A] box)
: ((Cons[A] val | Nil[A] val) , (Cons[A] val | Nil[A] val))
Builds a list by dropping the first n elements.
fun val drop( n: USize val) : (Cons[A] val | Nil[A] val)
Builds a list by dropping elements from the front of the list until one fails to satisfy the provided predicate.
fun val drop_while(
f: {(val->A): Bool}[A] box)
: (Cons[A] val | Nil[A] val)
Builds a list of the first n elements.
fun val take( n: USize val) : (Cons[A] val | Nil[A] val)
Builds a list of elements satisfying the provided predicate until one does not.
fun val take_while(
f: {(val->A): Bool}[A] box)
: (Cons[A] val | Nil[A] val)
Private helper for reverse, recursively working on elements.
fun val _reverse( l: (Cons[A] val | Nil[A] val), acc: (Cons[A] val | Nil[A] val)) : (Cons[A] val | Nil[A] val)
Private helper for concat that recursively builds the new list.
fun val _concat( l: (Cons[A] val | Nil[A] val), acc: (Cons[A] val | Nil[A] val)) : (Cons[A] val | Nil[A] val)
Private helper for map, recursively applying function to elements.
fun box _map[B: B](
l: (Cons[A] val | Nil[A] val),
f: {(val->A): val->B}[A, B] box,
acc: (Cons[B] val | Nil[B] val))
: (Cons[B] val | Nil[B] val)
Private helper for flat_map, recursively working on elements.
fun box _flat_map[B: B](
l: (Cons[A] val | Nil[A] val),
f: {(val->A): List[B]}[A, B] box,
acc: (Cons[B] val | Nil[B] val))
: (Cons[B] val | Nil[B] val)
Prepends l in reverse order onto target
fun tag _rev_prepend[B: B]( l: (Cons[B] val | Nil[B] val), target: (Cons[B] val | Nil[B] val)) : (Cons[B] val | Nil[B] val)
Private helper for for_each, recursively working on elements.
fun box _for_each(
l: (Cons[A] val | Nil[A] val),
f: {(val->A)}[A] box)
: None val
Private helper for filter, recursively working on elements, keeping those that match the predicate and discarding those that don't.
fun box _filter(
l: (Cons[A] val | Nil[A] val),
f: {(val->A): Bool}[A] box,
acc: (Cons[A] val | Nil[A] val))
: (Cons[A] val | Nil[A] val)
Private helper for fold, recursively working on elements.
fun val _fold[B: B](
l: (Cons[A] val | Nil[A] val),
f: {(B, val->A): B^}[A, B] box,
acc: B)
: B
Private helper for every, recursively testing predicate on elements, returning false immediately on an element that fails to satisfy the predicate.
fun box _every(
l: (Cons[A] val | Nil[A] val),
f: {(val->A): Bool}[A] box)
: Bool val
Private helper for exists, recursively testing predicate on elements, returning true immediately on an element satisfying the predicate.
fun box _exists(
l: (Cons[A] val | Nil[A] val),
f: {(val->A): Bool}[A] box)
: Bool val
© 2016-2018, The Pony Developers
© 2014-2015, Causality Ltd.
Licensed under the BSD 2-Clause License.
https://stdlib.ponylang.io/collections-persistent-Cons