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38 lines
727 B
38 lines
727 B
5 years ago
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package main
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import "fmt"
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func main() {
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zero, one, two, three := 0, 1, 2, 3
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list := []*int{&one, &two, nil, &three, &zero}
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// this will work, as the values will be evaluated
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// "lazily" - the nested functions will never
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// be executed, thus it will never panic.
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fmt.Printf("%v\n", myFold(mulLazy, 1, list))
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// This will panic.
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fmt.Printf("%v\n", foldl(mul, 1, list))
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}
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func mul(x int, y *int) int {
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if *y == 0 {
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return 0
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}
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return x * *y
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}
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func mulLazy(x func() int, y *int) func() int {
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return func() int {
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if *y == 0 {
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return 0
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}
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return x() * *y
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}
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}
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func myFold(f func(func() int, *int) func() int, acc int, list []*int) int {
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a := func() int { return acc }
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a = foldl(f, a, list)
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return a()
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}
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