optutils

optutils is a utility module to work with v's option type.

Usage

What it does basically:

some_val := ?string("something here")

x := if some_val {
    return x
} else {
    return ""
}

it help you to test whether there is anything in a option variable, if there is something, you get back your value else you can have further operation.

---

Let's start with a basic example, unwrap a value in option.

unwrap_or , unwrap a value from option type, if value is none , it will return the or value. or value has to be the same type of wrapped value.

import optutils

fn main() {
    some_val := ?string(none)

    val2 := optutils.unwrap_or(some_val, "")
    
    println(val2)

    // ""
}

unwrap_or_other , unwrap a value from option type or return value with another type, if value is none , it will return the or value.

import optutils

fn main() {
    some_val2 := ?string(none)

    // unwrap string option, if string option is none
    // return int 1
    option_2 := optutils.unwrap_or_other(some_val2, 1)
    
    if option_2 is string {
        val3 := string(option_2)
        println("string: ${val3}")
    } else if option_2 is int {
        val4 := int(option_2)
        println("int: ${val4}")
    }

    // int: 1
}

unwrap_or_default , unwrap a value from option type or return the type default value. For example, int default value is 0, bool default value is false.

import optutils

struct TestStruct {
    a string 
    b int
    c bool
    d f64
    e []string
}

fn main() {
    some_val3 := ?TestStruct(none)

    val5 := optutils.unwrap_or_default(some_val3)
    
    println(val5)

    // TestStruct{
    //   a: ''
    //   b: 0
    //   c: false
    //   d: 0.0
    //   e: []
    // }

    some_val4 := ?string(none)

    val6 := optutils.unwrap_or_default(some_val4)

    println(val6)
    // NIL

    println(val6 == "")
    // true
}

unwrap_then , other than optutils.unwrap_or_other , you can use optutils.unwrap_then(x, fn(y)) to return a value with different data type. Due to the callback function, you can do even more before returning a value. There might be error when unwrapping the value, so you need to handle it with result .

import optutils

fn main() {
    some_val5 := ?int(0)

    val7 := optutils.unwrap_then(some_val5, fn (x int) bool {
        if x == 0 {
            return true
        } else {
            return false
        }
    })!

    println(val7)

    // true
}

try_map , return an option array based on the callback function, the callback function should return only the same data type, you can use it for further processing with the array.

import optutils

fn main() {
    some_arr := [0, 2, 4, 6, 8]

    map_val := optutils.try_map(some_arr, fn (x int) int {
        y := x/2
        return y
    })

    println(map_val)

    // Option[0, 1, 2, 3, 4]
}

unwrap_try_map , similar to the previous function, but unwrap the return value of try_map , you get an array instead.

import optutils

fn main() {
    some_arr := [0, 2, 4, 6, 8]

    umap_val := optutils.unwrap_try_map(some_arr, fn (x int) int {
        y := x/2
        return y
    })

    println(umap_val)

    // [0, 1, 2, 3, 4]
}

try_filter , return an option array based on the callback function, the callback function should return bool which used as a predicate.

import optutils

fn main() {
    some_arr := [0, 2, 4, 6, 8]

    filter_val := optutils.try_filter(some_arr, fn (x int) bool {
        return x/2 > 1
    })

    println(filter_val)

    //Option[4, 6, 8]
}

unwrap_try_filter , similar to previous function, but unwrap the return value of try_filter , you get an array instead.

import optutils

fn main() {
    some_arr := [0, 2, 4, 6, 8]

    ufilter_val := optutils.unwrap_try_filter(some_arr, fn (x int) bool {
        return x/2 > 1
    })

    println(ufilter_val)

    // [4, 6, 8]
}

is_equal , compare two option variables, return true if equal, else false

import optutils

fn main() {
    some_val := ?int(10)

    some_val2 := ?int(11)

    some_val3 := ?int(none)
    
    some_val4 := ?int(10)

    eq := optutils.is_equal(some_val, some_val2)

    eq2 := optutils.is_equal(some_val, some_val4)

    println("some_val equal some_val2? ${eq}")
    // false

    println("some_val equal some_val4? ${eq2}")
    // true
}

is_some , check if something in the option variable, return true if something, else false .

import optutils

fn main() {
    some_val := ?int(10)

    some := optutils.is_some(some_val)

    println("got something? ${some}")
    
    // true, it is something there
}

is_none , check if the option variable is none, return true if nothing, else false .

import optutils

fn main() {
    some_val := ?int(10)

    nothing := optutils.is_none(some_val3)

    println("got nothing? ${nothing}")

    // true, it is nothing there
}

---

Deprecated

unwrap , unwrap a value from option type, exception will be raised if operation failed, you can also use or to return a different value.

fn main() {
    some_val := ?string("hi, there!")

    val := some_val?
    
    val := optutils.unwrap(some_val)!

    val := optutils.unwrap(some_val) or { "the other value" }

    println(val)
    // hi, there!

    // however, we can do this directly.
    val := some_val or {"the other value"}
    
}

try_unwrap is deprecated, use or {} directly instead, v has a better offer.

fn main() {
    some_val := ?string(none)

    val := some_val or {"alternative"}
    
    val := optutils.try_unwrap(none_val) or {"alternative"}

    println(val)

    // alternative
}

due to the duplication, I recommend to use ? and or operator instead.

Using it

Install via vpm

v install jaar23.optutils

Install via Github

v install --git https://github.com/jaar23/optutils

import in your code

import optutils