Anonymous recursion: Difference between revisions
→{{header|Go}}: Add example using a closure
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=={{header|Go}}==
===Y combinator===
Y combinator solution. Go has no special support for anonymous recursion.
<syntaxhighlight lang="go">package main
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fib 40 = 102334155
fib undefined for negative numbers
</pre>
===Closure===
<syntaxhighlight lang="go">
package main
import (
"errors"
"fmt"
)
func fib(n int) (result int, err error) {
var fib func(int) int // Must be declared first so it can be called in the closure
fib = func(n int) int {
if n < 2 {
return n
}
return fib(n-1) + fib(n-2)
}
if n < 0 {
err = errors.New("negative n is forbidden")
return
}
result = fib(n)
return
}
func main() {
for i := -1; i <= 10; i++ {
if result, err := fib(i); err != nil {
fmt.Printf("fib(%d) returned error: %s\n", i, err)
} else {
fmt.Printf("fib(%d) = %d\n", i, result)
}
}
}
</syntaxhighlight>
{{out}}
<pre>
fib(-1) returned error: negative n is forbidden
fib(0) = 0
fib(1) = 1
fib(2) = 1
fib(3) = 2
fib(4) = 3
fib(5) = 5
fib(6) = 8
fib(7) = 13
fib(8) = 21
fib(9) = 34
fib(10) = 55
</pre>
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