3.59. kink/iter/ITER¶
Provides operations for iters or iterators.
- ITER.is?(Val)
- ITER.of_ifun($ifun)
- type iter
- Iter.ifun
- Iter.each($on_elem)
- Iter.concat
- Iter.chunk(Chunk_size)
- Iter.map($transform)
- Iter.concat_map($transform_to_iter)
- Iter.filter($include?)
- Iter.count($counted?)
- Iter.fold(Init $combine)
- Iter.reduce($combine)
- Iter.scan(Init $combine)
- Iter.scan_inside($combine)
- Iter.take_front(N)
- Iter.drop_front(N)
- Iter.take_while($include?)
- Iter.drop_while($exclude?)
- Iter.for_all?($ok?)
- Iter.for_any?($ok?)
- Iter.fetcher_thunk
- ITER.of(...Elems)
- ITER.chain(Xiter Yiter)
- ITER.zip(First_iter ...Other_iters)
- ITER.cycle($make_iter)
- ITER.lazy($make_iter)
- ITER.with_yield($body)
- ITER.of_each(Eacher)
3.59.1. ITER.is?(Val)¶
ITER.is? returns whether the Val is an iter.
3.59.2. ITER.of_ifun($ifun)¶
Makes an iter backed by the $ifun.
3.59.3. type iter¶
Unidirectional iterator.
An iter is backed by an ifun.
Iter.ifun¶
Returns the ifun backing the Iter.
Iter.each($on_elem)¶
Calls $on_elem for each elements of the Iter, then return the last result of $on_elem.
If $ifun has no elements, it returns nada.
Iter.concat¶
Returns an iter, which concatenates the elements of iters in the Iter.
The Iter must be an iter of iters.
Iter.chunk(Chunk_size)¶
Returns an iter of chunks with the Chunk_size.
For example, if the Iter contains E1, E2, E3, E4, E5, E6, E7, and Chunk_size is 2, this method returns an iter containing [E1 E2], [E3 E4] and [E5 E6]. The last E7 is ignored because there are not enough number of elements as a chunk.
Chunk_size must be an int num, and >= 1.
Iter.map($transform)¶
Returns an iter whose elements are transformed from the Iter by $transform.
When the Iter has elements E1, E2, ,,, , the result iter has elements transform(E1), transform(E2), ,,, .
Iter.concat_map($transform_to_iter)¶
Equivalent to call Iter.map($transform_to_iter).concat.
Iter.filter($include?)¶
Filters elements of $ifun by the predicate $include?.
The result iter only contains elements of the Iter which satisfy $include?. the order of elements are not changed.
Iter.count($counted?)¶
Returns the number of elements of the Iter which satisfy $counted?.
Iter.fold(Init $combine)¶
Accumulates elements of the Iter seeded by Init.
If the elements of the Iter is E1, E2, ,,, En_1, En, this fun returns combine(combine(,,,combine(combine(Init E1) E2),,, En_1) En).
If the Iter is empty, this fun returns Init.
Iter.reduce($combine)¶
Accumulates elements of the Iter mutually, then returns a maybe tuple.
If the Iter has elements E1, E2, E3, ,,, En_1, En, this method returns [combine(combine(,,,combine(combine(E1 E2) E3),,, En_1) En)].
If the Iter has a single element E, this method returns [E].
If the Iter is empty, this method returns [].
Iter.scan(Init $combine)¶
Returns an iter of accumulated vals, seeded by Init.
If the Iter has finite n elements E(1), E(2), ,,, E(n), the result iter has finite n+1 elements R(0), R(1), R(2), ,,, R(n).
If the Iter has infinite elements E(1), E(2), ,,, , the result iter has infinite elements R(0), R(1), R(2), ,,, .
In both cases, R(i) is given as below:
For i=0, R(0) = Init.
For i>=1, R(i) = combine(R(i - 1) E(i)).
Iter.scan_inside($combine)¶
Returns an iter of vals accumulated inside the Iter.
If the Iter is empty, the result iter is empty.
If the Iter has finite n (n >= 1) elements E(1), E(2), ,,, E(n), the result iter has finite n elements R(1), R(2), ,,, R(n).
If the Iter has infinite elements E(1), E(2), ,,, , the result iter has infinite elements R(1), R(2), ,,, .
In the latter two cases, R(i) is given as below:
For i=1, R(1) = E(1).
For i>=2, R(i) = combine(R(i - 1) E(i))
Iter.take_front(N)¶
Returns an iter containing the first N elements of the Iter, or all the elements if the Iter has less than N elements.
Iter.drop_front(N)¶
Returns an iter omitting the first N elements of the Iter, or an empty iter if the Iter has less than N elements.
Iter.take_while($include?)¶
Returns an iter of the longest initial prefix of the Iter, whose elements all satisfy $include?.
Iter.drop_while($exclude?)¶
Returns an iter after the longest initial prefix of the Iter whose elements all satisfy $exclude?.
Iter.for_all?($ok?)¶
Returns true if all the elements of the Iter satisfy $ok?. Returns false if at least one element of the Iter does not satisfy $ok?.
If the Iter is infinite, this method is not guaranteed to return.
Iter.for_any?($ok?)¶
Returns true if at least one element of the Iter satisfies $ok?. Returns fall if all the elements of the Iter does not satisfy $ok?.
If the Iter is infinite, this method is not guaranteed to return.
Iter.fetcher_thunk¶
Makes a stateful thunk to fetch each element of the Iter.
When the result thunk is called, it returns a list containing the current element and go to next, when there are remaining elements. Otherwise, it returns an empty list.
For example:
:Iter <- ['foo' 'bar' 'baz']
:fetch <- Iter.fetcher_thunk
print_line(fetch.repr) # => ["foo"]
print_line(fetch.repr) # => ["bar"]
print_line(fetch.repr) # => ["baz"]
print_line(fetch.repr) # => []
print_line(fetch.repr) # => []
3.59.4. ITER.of(...Elems)¶
Returns an iter containing the Elems.
3.59.5. ITER.chain(Xiter Yiter)¶
Chains the two iters.
If the Xiter has finite n elements X1, X2, ,,, Xn, and the Yiter has elements Y1, Y2, ,,, , the result iter has X1, X2, ,,, Xn, Y1, Y2, ,,, .
If the Xiter is infinite, the result iter has the same elements as ones of the Xiter.
3.59.6. ITER.zip(First_iter ...Other_iters)¶
Zips the elements of the given iters.
For example, an iter X has elements X1, X2, X3, ,,, , an iter Y has elements Y1, Y2, Y3, ,,, , and an iter Z has elements Z1, Z2, Z3, ,,, , zip(X Y Z) returns an iter containing [X1 Y1 Z1], [X2 Y2 Z2], [X3 Y3 Z3], ,,, .
The size of the result iter is the minimum of the size of the given iters.
3.59.7. ITER.cycle($make_iter)¶
Returns an iter which repeatedly concatenates elements of iters created by the $make_iter thunk.
If the $make_iter makes an empty iter, the result iter is terminated there.
3.59.8. ITER.lazy($make_iter)¶
Returns an iter whose elements are same as the iter created by the $make_iter.
3.59.9. ITER.with_yield($body)¶
Makes an iter of elements yielded in $body.
$body must take an unary fun $yield as the arg, When $yield is called with a vals in $body, those vals will be the elements of the result iter.
For example:
:ITER.require_from('kink/iter/')
:Iter = ITER.with_yield{(:yield)
yield('foo')
yield('bar')
yield('baz')
}
Iter.each{(:Str)
stdout.print_line(Str)
}
# Output:
# foo
# bar
# baz
This fun provides functionality equivalent to Python's generators.
3.59.10. ITER.of_each(Eacher)¶
Makes an iter of elements which is enumerated in Eacher.each.