Fibonacci in Go

fib.go

package main

import "fmt"
import "math/big"

func main() {
    f := fibonacci()
    for i := 0; i < 100; i++ {
        fmt.Println(f(i))
    }
}

func fibonacci() (func(int) *big.Int) {
    s := map[int]*big.Int { 0:big.NewInt(1), 1:big.NewInt(1) }

    var f func(int) (*big.Int)
    f = func(n int) (*big.Int) {
        if v,ok := s[n]; ok { return v }
        s[n] = big.NewInt(0).Add(f(n-2), f(n-1))
        return s[n]
    }

    return func(i int) *big.Int {
        return f(i)
    }
}