# Implicit Effects

Explicitly creating effects to update properties can be tedious. Vide provides a
way to *implicitly* create an effect to update properties.

```lua
local create = vide.create
local source = vide.source

local function Counter()
    local count = source(0)

    return create "TextButton" {
        Activated = function()
            count(count() + 1)
        end,

        Text = function()
            return "count: " .. count()
        end
    }
end
```

This example is equivalent to the example seen on the previous page.

Instead of explicitly creating an effect, assigning a (non-event) property a
function will implicitly create an effect to update that property anytime a
source used within is updated.

Just like effects, the function is ran immediately in a reactive scope to set
the property initially and determine what sources are being used.

## Children

Children can also be set in a similar manner. A source passed as a child (passed
with a number key instead of string key) can return an instance or an array of
instances. Vide will automatically unparent removed instances and parent new
instances when that source's stored instances change.

```lua
local items = source {
    create "TextLabel" { Text = "A" }
}

local function List(props: { children: () -> { Instance } })
    return create "Frame" {
        create "UIListLayout" {},
        props.children
    }
end

local list = List { children = items } -- creates a list with a single text label "A"

items {
    create "TextLabel" { Text = "B" },
    create "TextLabel" { Text = "C" }
}

-- this will automatically unparent the text label "A", and parent the labels "B" and "C".
```