Tuesday, December 01, 2009

Fibonacci in Go

I've been playing around with Go a bit. Here's what I think is the most Go-like solution to producing the Fibonacci sequence.
package main

import "fmt"

func dup3(in <-chan int) (<-chan int,<-chan int,<-chan int) {
a,b,c := make(chan int,2),make(chan int,2),make(chan int,2);
go func() { for { x := <-in; a <- x; b <- x; c <- x } }();
return a,b,c

func fib() <-chan int {
x := make(chan int,2);
a,b,out := dup3(x);
go func() { x<-0; x<-1; <-a; for { x<- <-a + <-b } }();
return out

func main() {
x := fib();
for i:=0; i<10; i++ { fmt.Println(<-x) }
I like it because I only ever declare a single integer variable, and the rest goes through chans. This solution is inspired by Haskell's concise "fib = 0:zipWith (+) fib (1:fib)". Any comments are most welcome. In particular, if there were a way to accomplish it (in the same style) without the buffered chans, that would be pretty cool (though I'd be a bit surprised, since it doesn't seem possible at first glance).