Tengo provides built-in functions that are always available without importing a module. Many come in mutating and non-mutating pairs.
fmt := import("fmt")fmt.println(len("hello"))
fmt.println(len([1, 2, 3]))
fmt.println(len({a: 1, b: 2}))fmt.println(range(0, 5))
fmt.println(range(0, 10, 2))m := {name: "Tengo", version: 3}
m2 := assoc(m, "stable", true)
fmt.println(m2)
m3 := dissoc(m, "version")
fmt.println(m3)counts := {a: 1, b: 2, c: 3}
delete(counts, "b")
fmt.println(counts)arr := [1, 2, 3, 4]
arr2 := insert(arr, 2, 99)
fmt.println(arr2)
arr3 := remove(arr, 0)
fmt.println(arr3)nums := [10, 20, 30, 40, 50]
removed := splice(nums, 1, 2)
fmt.println(nums)
fmt.println(removed)fmt.println(format("%-8s %d", "score:", 42))fmt.println(is_int(42))
fmt.println(is_string("hi"))
fmt.println(is_callable(func() {}))try it
5
3
2
[0, 1, 2, 3, 4]
[0, 2, 4, 6, 8]
{version: 3, stable: true, name: "Tengo"}
{name: "Tengo"}
{a: 1, c: 3}
[1, 2, 99, 3, 4]
[2, 3, 4]
[10, 40, 50]
[20, 30]
score: 42
true
true
true