mirror of
https://github.com/nim-lang/Nim.git
synced 2025-12-30 01:44:37 +00:00
686c75cef0
A for expression now can have a generated iterator, allowing for more composable iterables
55 lines
1.0 KiB
Nim
55 lines
1.0 KiB
Nim
discard """
|
|
output: '''30
|
|
60
|
|
90
|
|
150
|
|
180
|
|
210
|
|
240
|
|
60
|
|
180
|
|
240
|
|
[60, 180, 240]
|
|
[60, 180]'''
|
|
"""
|
|
import std/enumerate
|
|
|
|
template map[T; Y](i: iterable[T], fn: proc(x: T): Y): untyped =
|
|
iterator internal(): Y {.gensym.} =
|
|
for it in i:
|
|
yield fn(it)
|
|
internal()
|
|
|
|
template filter[T](i: iterable[T], fn: proc(x: T): bool): untyped =
|
|
iterator internal(): T {.gensym.} =
|
|
for it in i:
|
|
if fn(it):
|
|
yield it
|
|
internal()
|
|
|
|
template group[T](i: iterable[T], amount: static int): untyped =
|
|
iterator internal(): array[amount, T] {.gensym.} =
|
|
var val: array[amount, T]
|
|
for ind, it in enumerate i:
|
|
val[ind mod amount] = it
|
|
if ind mod amount == amount - 1:
|
|
yield val
|
|
internal()
|
|
|
|
var a = [10, 20, 30, 50, 60, 70, 80]
|
|
|
|
proc mapFn(x: int): int = x * 3
|
|
proc filterFn(x: int): bool = x mod 20 == 0
|
|
|
|
for x in a.items.map(mapFn):
|
|
echo x
|
|
|
|
for y in a.items.map(mapFn).filter(filterFn):
|
|
echo y
|
|
|
|
for y in a.items.map(mapFn).filter(filterFn).group(3):
|
|
echo y
|
|
|
|
for y in a.items.map(mapFn).filter(filterFn).group(2):
|
|
echo y
|