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|
discard """
output: '''
Selecting 2
1.0
Selecting 4
2.0
'''
"""
# bug #5522
import macros, sugar, sequtils
proc tryS(f: () -> void): void =
(try: f() except: discard)
template trySTImpl(body: untyped): untyped =
tryS do() -> auto:
`body`
macro tryST*(body: untyped): untyped =
var b = if body.kind == nnkDo: body[^1] else: body
result = quote do:
trySTImpl((block:
`b`
))
iterator testIt(): int {.closure.} =
for x in 0..10:
yield x
var xs = newSeq[int]()
proc test = tryST do:
for x in testIt():
xs.add(x)
test()
doAssert xs == toSeq(0..10)
# bug #5690
proc filter[T](it: (iterator : T), f: proc(x: T): bool): (iterator : T) =
return iterator (): T {.closure.} =
for x in it():
if f(x):
yield x
proc len[T](it : iterator : T) : Natural =
for i in it():
result += 1
proc simpleSeqIterator(s :seq[int]) : iterator : int =
iterator it: int {.closure.} =
for x in s:
yield x
result = it
let a = newSeq[int](99)
doAssert len(simpleSeqIterator(a).filter(proc(x : int) : bool = true)) == 99
# bug #5340
proc where[A](input: seq[A], filter: (A) -> bool): iterator (): A =
result = iterator (): A {.closure.} =
for item in input:
if filter(item):
yield item
proc select[A,B](input: iterator(): A {.closure.}, selector: (A) -> B): iterator (): B {.closure.} =
result = iterator (): B =
for item in input():
echo "Selecting " & $item
yield selector(item)
let query = @[1,2,3,4].where(x=>x mod 2==0).select((x)=>x/2)
for i in query():
echo $i
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