Iter[A: A]¶

Wrapper class containing methods to modify iterators.

class ref Iter[A: A] is
  Iterator[A] ref

Implements¶

Iterator[A] ref

Constructors¶

create¶

[Source]

new ref create(
  iter: Iterator[A] ref)
: Iter[A] ref^

Parameters¶

iter: Iterator[A] ref

Returns¶

Iter[A] ref^

maybe¶

[Source]

new ref maybe(
  value: (A | None val))
: Iter[A] ref^

Parameters¶

value: (A | None val)

Returns¶

Iter[A] ref^

chain¶

[Source]

Take an iterator of iterators and return an Iter containing the items of the first one, then the second one, and so on.

Example¶

let xs = [as I64: 1; 2].values()
let ys = [as I64: 3; 4].values()

Iter[I64].chain([xs; ys].values())

1 2 3 4

new ref chain(
  outer_iterator: Iterator[Iterator[A] ref] ref)
: Iter[A] ref^

Parameters¶

outer_iterator: Iterator[Iterator[A] ref] ref

Returns¶

Iter[A] ref^

repeat_value¶

[Source]

Create an iterator that returns the given value forever.

Example¶

Iter[U32].repeat_value(7)

7 7 7 7 7 7 7 7 7 ...

new ref repeat_value(
  value: A)
: Iter[A] ref^

Parameters¶

value: A

Returns¶

Iter[A] ref^

Public Functions¶

has_next¶

[Source]

fun ref has_next()
: Bool val

Returns¶

Bool val

next¶

[Source]

fun ref next()
: A ?

Returns¶

A ?

next_or¶

[Source]

Return the next value, or the given default.

Example¶

let x: (U64 | None) = 42
Iter[U64].maybe(x).next_or(0)

42

fun ref next_or(
  default: A)
: A

Parameters¶

default: A

Returns¶

A

map_stateful[B: B]¶

[Source]

Allows stateful transformation of each element from the iterator, similar to map.

fun ref map_stateful[B: B](
  f: {ref(A!): B ?}[A, B] ref)
: Iter[B] ref^

Parameters¶

f: {ref(A!): B ?}[A, B] ref

Returns¶

Iter[B] ref^

filter_stateful¶

[Source]

Allows filtering of elements based on a stateful adapter, similar to filter.

fun ref filter_stateful(
  f: {ref(A!): Bool ?}[A] ref)
: Iter[A!] ref^

Parameters¶

f: {ref(A!): Bool ?}[A] ref

Returns¶

Iter[A!] ref^

filter_map_stateful[B: B]¶

[Source]

Allows stateful modification to the stream of elements from an iterator, similar to filter_map.

fun ref filter_map_stateful[B: B](
  f: {ref(A!): (B^ | None) ?}[A, B] ref)
: Iter[B] ref^

Parameters¶

f: {ref(A!): (B^ | None) ?}[A, B] ref

Returns¶

Iter[B] ref^

all¶

[Source]

Return false if at least one value of the iterator fails to match the predicate f. This method short-circuits at the first value where the predicate returns false, otherwise true is returned.

Examples¶

Iter[I64]([2; 4; 6].values())
  .all({(x) => (x % 2) == 0 })

true

Iter[I64]([2; 3; 4].values())
  .all({(x) => (x % 2) == 0 })

false

fun ref all(
  f: {(A!): Bool ?}[A] box)
: Bool val

Parameters¶

f: {(A!): Bool ?}[A] box

Returns¶

Bool val

any¶

[Source]

Return true if at least one value of the iterator matches the predicate f. This method short-circuits at the first value where the predicate returns true, otherwise false is returned.

Examples¶

Iter[I64]([2; 4; 6].values())
  .any({(I64) => (x % 2) == 1 })

false

Iter[I64]([2; 3; 4].values())
  .any({(I64) => (x % 2) == 1 })

true

fun ref any(
  f: {(A!): Bool ?}[A] box)
: Bool val

Parameters¶

f: {(A!): Bool ?}[A] box

Returns¶

Bool val

collect[optional B: Seq[A!] ref]¶

[Source]

Push each value from the iterator into the collection coll.

Example¶

Iter[I64]([1; 2; 3].values())
  .collect(Array[I64](3))

[1, 2, 3]

fun ref collect[optional B: Seq[A!] ref](
  coll: B)
: B^

Parameters¶

coll: B

Returns¶

B^

count¶

[Source]

Return the number of values in the iterator.

Example¶

Iter[I64]([1; 2; 3].values())
  .count()

3

fun ref count()
: USize val

Returns¶

USize val

cycle¶

[Source]

Repeatedly cycle through the values from the iterator.

WARNING: The values returned by the original iterator are cached, so the input iterator should be finite.

Example¶

Iter[I64]([1; 2; 3].values())
  .cycle()

1 2 3 1 2 3 1 2 3 ...

fun ref cycle()
: Iter[A!] ref^

Returns¶

Iter[A!] ref^

dedup[optional H: HashFunction[A] val]¶

[Source]

Return an iterator that removes duplicates from consecutive identical elements. Equality is determined by the HashFunction H.

Example¶

Iter[USize]([as USize: 1; 1; 2; 3; 3; 2; 2].values())
  .dedup()

1 2 3 2

fun ref dedup[optional H: HashFunction[A] val]()
: Iter[A!] ref^

Returns¶

Iter[A!] ref^

enum[optional B: (Real[B] val & (I8 val | I16 val | I32 val | I64 val | I128 val | ILong val | ISize val | U8 val | U16 val | U32 val | U64 val | U128 val | ULong val | USize val | F32 val | F64 val))]¶

[Source]

An iterator which yields the current iteration count as well as the next value from the iterator.

Example¶

Iter[I64]([1; 2; 3].values())
  .enum()

(0, 1) (1, 2) (2, 3)

fun ref enum[optional B: (Real[B] val & (I8 val | I16 val | I32 val | 
    I64 val | I128 val | ILong val | 
    ISize val | U8 val | U16 val | 
    U32 val | U64 val | U128 val | 
    ULong val | USize val | F32 val | 
    F64 val))]()
: Iter[(B , A)] ref^

Returns¶

Iter[(B , A)] ref^

filter¶

[Source]

Return an iterator that only returns items that match the predicate f.

Example¶

Iter[I64]([1; 2; 3; 4; 5; 6].values())
  .filter({(x) => (x % 2) == 0 })

2 4 6

fun ref filter(
  f: {(A!): Bool ?}[A] box)
: Iter[A!] ref^

Parameters¶

f: {(A!): Bool ?}[A] box

Returns¶

Iter[A!] ref^

find¶

[Source]

Return the nth value in the iterator that satisfies the predicate f.

Examples¶

Iter[I64]([1; 2; 3].values())
  .find({(x) => (x % 2) == 0 })

2

Iter[I64]([1; 2; 3; 4].values())
  .find({(x) => (x % 2) == 0 }, 2)

4

fun ref find(
  f: {(A!): Bool ?}[A] box,
  n: USize val = 1)
: A! ?

Parameters¶

f: {(A!): Bool ?}[A] box
n: USize val = 1

Returns¶

A! ?

filter_map[B: B]¶

[Source]

Return an iterator which applies f to each element. If None is returned, then the iterator will try again by applying f to the next element. Otherwise, the value of type B is returned.

Example¶

Iter[I64]([as I64: 1; -2; 4; 7; -5])
  .filter_map[USize](
    {(i: I64): (USize | None) => if i >= 0 then i.usize() end })

1 4 7

```pony
fun ref filter_map[B: B](
  f: {(A!): (B^ | None) ?}[A, B] box)
: Iter[B] ref^

Parameters¶

f: {(A!): (B^ | None) ?}[A, B] box

Returns¶

Iter[B] ref^

flat_map[B: B]¶

[Source]

Return an iterator over the values of the iterators produced from the application of the given function.

Example¶

Iter[String](["alpha"; "beta"; "gamma"])
  .flat_map[U8]({(s: String): Iterator[U8] => s.values() })

a l p h a b e t a g a m m a

fun ref flat_map[B: B](
  f: {(A!): Iterator[B] ?}[A, B] box)
: Iter[B] ref^

Parameters¶

f: {(A!): Iterator[B] ?}[A, B] box

Returns¶

Iter[B] ref^

fold[B: B]¶

[Source]

Apply a function to every element, producing an accumulated value.

Example¶

Iter[I64]([1; 2; 3].values())
  .fold[I64](0, {(sum, x) => sum + x })

6

fun ref fold[B: B](
  acc: B,
  f: {(B, A!): B^}[A, B] box)
: B^

Parameters¶

acc: B
f: {(B, A!): B^}[A, B] box

Returns¶

B^

fold_partial[B: B]¶

[Source]

A partial version of fold.

fun ref fold_partial[B: B](
  acc: B,
  f: {(B, A!): B^ ?}[A, B] box)
: B^ ?

Parameters¶

acc: B
f: {(B, A!): B^ ?}[A, B] box

Returns¶

B^ ?

interleave¶

[Source]

Return an iterator that alternates the values of the original iterator and the other until both run out.

Example¶

Iter[USize](Range(0, 4))
  .interleave(Range(4, 6))

0 4 1 5 2 3

fun ref interleave(
  other: Iterator[A] ref)
: Iter[A!] ref

Parameters¶

other: Iterator[A] ref

Returns¶

Iter[A!] ref

interleave_shortest¶

[Source]

Return an iterator that alternates the values of the original iterator and the other until one of them runs out.

Example¶

Iter[USize](Range(0, 4))
  .interleave_shortest(Range(4, 6))

0 4 1 5 2

fun ref interleave_shortest(
  other: Iterator[A] ref)
: Iter[A!] ref

Parameters¶

other: Iterator[A] ref

Returns¶

Iter[A!] ref

intersperse¶

[Source]

Return an iterator that yields the value after every n elements of the original iterator.

Example¶

Iter[USize](Range(0, 3))
  .intersperse(8)

0 8 1 8 2

fun ref intersperse(
  value: A,
  n: USize val = 1)
: Iter[A!] ref

Parameters¶

value: A
n: USize val = 1

Returns¶

Iter[A!] ref

last¶

[Source]

Return the last value of the iterator.

Example¶

Iter[I64]([1; 2; 3].values())
  .last()

3

fun ref last()
: A ?

Returns¶

A ?

map[B: B]¶

[Source]

Return an iterator where each item's value is the application of the given function to the value in the original iterator.

Example¶

Iter[I64]([1; 2; 3].values())
  .map[I64]({(x) => x * x })

1 4 9

fun ref map[B: B](
  f: {(A!): B ?}[A, B] box)
: Iter[B] ref^

Parameters¶

f: {(A!): B ?}[A, B] box

Returns¶

Iter[B] ref^

nth¶

[Source]

Return the nth value of the iterator.

Example¶

Iter[I64]([1; 2; 3].values())
  .nth(2)

2

fun ref nth(
  n: USize val)
: A ?

Parameters¶

n: USize val

Returns¶

A ?

run¶

[Source]

Iterate through the values of the iterator without a for loop. The function on_error will be called if the iterator's has_next method returns true but its next method throws an error.

Example¶

Iter[I64]([1; 2; 3].values())
  .map[None]({(x) => env.out.print(x.string()) })
  .run()

1
2
3

fun ref run(
  on_error: {ref()}[A] ref = lambda)
: None val

Parameters¶

on_error: {ref()}[A] ref = lambda

Returns¶

None val

skip¶

[Source]

Skip the first n values of the iterator.

Example¶

Iter[I64]([1; 2; 3; 4; 5; 6].values())
  .skip(3)

4 5 6

Iter[I64]([1; 2; 3].values())
  .skip(3)
  .has_next()

false

fun ref skip(
  n: USize val)
: Iter[A] ref^

Parameters¶

n: USize val

Returns¶

Iter[A] ref^

skip_while¶

[Source]

Skip values of the iterator while the predicate f returns true.

Example¶

Iter[I64]([1; 2; 3; 4; 5; 6].values())
  .skip_while({(x) => x < 4 })

4 5 6

fun ref skip_while(
  f: {(A!): Bool ?}[A] box)
: Iter[A!] ref^

Parameters¶

f: {(A!): Bool ?}[A] box

Returns¶

Iter[A!] ref^

step_by¶

[Source]

Return an iterator that yields every nth element of the original iterator. n == 0 is treated like n == 1 rather than an error.

Example¶

Iter[USize](Range(0, 10))
  .step_by(2)

1 3 5 7 9

fun ref step_by(
  n: USize val = 1)
: Iter[A!] ref

Parameters¶

n: USize val = 1

Returns¶

Iter[A!] ref

take¶

[Source]

Return an iterator for the first n elements.

Example¶

Iter[I64]([1; 2; 3; 4; 5; 6].values())
  .take(3)

1 2 3

fun ref take(
  n: USize val)
: Iter[A] ref^

Parameters¶

n: USize val

Returns¶

Iter[A] ref^

take_while¶

[Source]

Return an iterator that returns values while the predicate f returns true. This iterator short-circuits the first time that f returns false or raises an error.

Example¶

Iter[I64]([1; 2; 3; 4; 5; 6].values())
  .take_while({(x) => x < 4 })

1 2 3

fun ref take_while(
  f: {(A!): Bool ?}[A] box)
: Iter[A!] ref^

Parameters¶

f: {(A!): Bool ?}[A] box

Returns¶

Iter[A!] ref^

unique[optional H: HashFunction[A] val]¶

[Source]

Return an iterator that filters out elements that have already been produced. Uniqueness is determined by the HashFunction H.

Example¶

Iter[USize]([as USize: 1; 2; 1; 1; 3; 4; 1].values())
    .unique()

1 2 3 4

fun ref unique[optional H: HashFunction[A] val]()
: Iter[A!] ref^

Returns¶

Iter[A!] ref^

zip[B: B]¶

[Source]

Zip two iterators together so that each call to next() results in a tuple with the next value of the first iterator and the next value of the second iterator. The number of items returned is the minimum of the number of items returned by the two iterators.

Example¶

Iter[I64]([1; 2].values())
  .zip[I64]([3; 4].values())

(1, 3) (2, 4)

fun ref zip[B: B](
  i2: Iterator[B] ref)
: Iter[(A , B)] ref^

Parameters¶

i2: Iterator[B] ref

Returns¶

Iter[(A , B)] ref^

zip2[B: B, C: C]¶

[Source]

Zip three iterators together so that each call to next() results in a tuple with the next value of the first iterator, the next value of the second iterator, and the value of the third iterator. The number of items returned is the minimum of the number of items returned by the three iterators.

fun ref zip2[B: B, C: C](
  i2: Iterator[B] ref,
  i3: Iterator[C] ref)
: Iter[(A , B , C)] ref^

Parameters¶

i2: Iterator[B] ref
i3: Iterator[C] ref

Returns¶

Iter[(A , B , C)] ref^

zip3[B: B, C: C, D: D]¶

[Source]

Zip four iterators together so that each call to next() results in a tuple with the next value of each of the iterators. The number of items returned is the minimum of the number of items returned by the iterators.

fun ref zip3[B: B, C: C, D: D](
  i2: Iterator[B] ref,
  i3: Iterator[C] ref,
  i4: Iterator[D] ref)
: Iter[(A , B , C , D)] ref^

Parameters¶

i2: Iterator[B] ref
i3: Iterator[C] ref
i4: Iterator[D] ref

Returns¶

Iter[(A , B , C , D)] ref^

zip4[B: B, C: C, D: D, E: E]¶

[Source]

Zip five iterators together so that each call to next() results in a tuple with the next value of each of the iterators. The number of items returned is the minimum of the number of items returned by the iterators.

fun ref zip4[B: B, C: C, D: D, E: E](
  i2: Iterator[B] ref,
  i3: Iterator[C] ref,
  i4: Iterator[D] ref,
  i5: Iterator[E] ref)
: Iter[(A , B , C , D , E)] ref^

Parameters¶

i2: Iterator[B] ref
i3: Iterator[C] ref
i4: Iterator[D] ref
i5: Iterator[E] ref

Returns¶

Iter[(A , B , C , D , E)] ref^