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Transformations
===============
.. module:: fun
.. function:: map(fun, gen, param, state)
iterator:map(fun)
:param fun: a function to apply
:type fun: (function(...) -> ...)
:returns: a new iterator
Return a new iterator by applying the **fun** to each element of
``gen, param, state`` iterator. The mapping is performed on the fly
and no values are buffered.
Examples:
.. code-block:: lua
> each(print, map(function(x) return 2 * x end, range(4)))
2
4
6
8
fun = function(...) return 'map', ... end
> each(print, map(fun, range(4)))
map 1
map 2
map 3
map 4
.. function:: enumerate(gen, param, state)
iterator:enumerate()
:returns: a new iterator
Return a new iterator by enumerating all elements of the
``gen, param, state`` iterator starting from ``1``. The mapping is performed
on the fly and no values are buffered.
Examples:
.. code-block:: lua
> each(print, enumerate({"a", "b", "c", "d", "e"}))
1 a
2 b
3 c
4 d
5 e
> each(print, enumerate(zip({"one", "two", "three", "four", "five"},
{"a", "b", "c", "d", "e"})))
1 one a
2 two b
3 three c
4 four d
5 five e
.. function:: intersperse(x, gen, param, state)
iterator:intersperse(x)
:type x: any
:returns: a new iterator
Return a new iterator where the **x** value is interspersed between the
elements of the source iterator. The **x** value can also be added as a
last element of returning iterator if the source iterator contains the odd
number of elements.
Examples:
.. code-block:: lua
> each(print, intersperse("x", {"a", "b", "c", "d", "e"}))
a
x
b
x
c
x
d
x
e
x
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