Wikipedia: Higher-order function
Functions are first-class values in Tengo. You can pass them as arguments, return them from other functions, and store them in maps or arrays — enabling map, filter, and reduce patterns without a stdlib.
fmt := import("fmt")map_fn := func(arr, f) {
result := []
for _, v in arr {
result = append(result, f(v))
}
return result
}
doubled := map_fn([1, 2, 3, 4], func(x) { return x * 2 })
fmt.println(doubled)filter_fn := func(arr, pred) {
result := []
for _, v in arr {
if pred(v) {
result = append(result, v)
}
}
return result
}
evens := filter_fn([1, 2, 3, 4, 5, 6], func(x) { return x % 2 == 0 })
fmt.println(evens)reduce_fn := func(arr, initial, f) {
acc := initial
for _, v in arr {
acc = f(acc, v)
}
return acc
}
total := reduce_fn([1, 2, 3, 4, 5], 0, func(a, b) { return a + b })
fmt.println(total)multiplier := func(factor) {
return func(x) { return x * factor }
}
triple := multiplier(3)
fmt.println(triple(7))
fmt.println(map_fn([1, 2, 3], multiplier(10)))try it
[2, 4, 6, 8] [2, 4, 6] 15 21 [10, 20, 30]