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@akitaonrails
Last active May 29, 2016 03:47
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Go to Crystal: Concurrency Tour #2 (https://tour.golang.org/concurrency/2)
def sum(s : Array(Int32), c : Channel(Int32))
c.send s.reduce(0) { |sum, v| sum + v }
end
def main
s = [7, 2, 8, -9, 4, 0]
c = Channel(Int32).new
spawn {
sum(s[0..((s.size / 2) - 1)], c)
}
spawn {
sum(s[(s.size / 2)..-1], c)
}
x, y = c.receive, c.receive
puts "x, y = #{x}, #{y}"
end
main
package main
import "fmt"
func sum(s []int, c chan int) {
sum := 0
for _, v := range s {
sum += v
}
c <- sum // send sum to c
}
func main() {
s := []int{7, 2, 8, -9, 4, 0}
c := make(chan int)
go sum(s[:len(s)/2], c)
go sum(s[len(s)/2:], c)
x, y := <-c, <-c // receive from c
fmt.Println(x, y, x+y)
}
@asterite
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@akitaonrails Nice! But I'd say this is more idiomatic Crystal (no need for main, can use spawn without a block, like in Go):

def sum(s : Array(Int32), c : Channel(Int32))
  c.send s.sum
end

s = [7, 2, 8, -9, 4, 0]
c = Channel(Int32).new
spawn sum(s[0..((s.size / 2) - 1)], c)
spawn sum(s[(s.size / 2)..-1], c)
x, y = c.receive, c.receive

puts "x, y = #{x}, #{y}"

Or maybe even this (type annotations are not required in arguments):

def sum(values, channel)
  channel.send values.sum
end

s = [7, 2, 8, -9, 4, 0]
c = Channel(Int32).new
spawn sum(s[0..((s.size / 2) - 1)], c)
spawn sum(s[(s.size / 2)..-1], c)
x, y = c.receive, c.receive

puts "x, y = #{x}, #{y}"

@akitaonrails
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Author

Great, I agree, I was just doing a 1 to 1 translation just to show the difference but your version is definitely better.

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