Shop System

This example shows a simple shop system using Reheaven.

The shop has coins, a selected item, and a purchase message.

Key Point

Shop actions change state. The UI reacts automatically.

Shop State

ShopState.lua

local signal = Reheaven.signal
local computed = Reheaven.computed

local coins, setCoins = signal(250)
local selectedItem, setSelectedItem = signal(nil)
local message, setMessage = signal("")

local itemCost = computed(function()
    local item = selectedItem()

    if item == "Sword" then
        return 100
    elseif item == "Shield" then
        return 150
    end

    return 0
end)

local canBuy = computed(function()
    return selectedItem() ~= nil and coins() >= itemCost()
end)

Shop Actions

ShopActions.lua

local function selectItem(itemName)
    setSelectedItem(itemName)
    setMessage(`Selected {itemName}`)
end

local function buySelectedItem()
    if not canBuy() then
        setMessage("Not enough coins")
        return
    end

    Reheaven.batch(function()
        setCoins(coins() - itemCost())
        setMessage(`Purchased {selectedItem()}!`)
        setSelectedItem(nil)
    end)
end

Shop UI

ShopUI.lua

local effect = Reheaven.effect

effect(function()
    coinsLabel.Text = `Coins: {coins()}`
end)

effect(function()
    local item = selectedItem()

    selectedItemLabel.Text = if item then `Selected: {item}` else "No item selected"
    priceLabel.Text = `Price: {itemCost()}`
    buyButton.Active = canBuy()
    buyButton.AutoButtonColor = canBuy()
end)

effect(function()
    messageLabel.Text = message()
end)

Button Input

ShopButtons.lua

swordButton.MouseButton1Click:Connect(function()
    selectItem("Sword")
end)

shieldButton.MouseButton1Click:Connect(function()
    selectItem("Shield")
end)

buyButton.MouseButton1Click:Connect(function()
    buySelectedItem()
end)

Shop Flow

Button clicked
↓
Shop action runs
↓
Shop state changes
↓
Computed values update
↓
UI reacts

Server Authority

For real purchases, validate the purchase on the server.

The client can show shop UI, but the server should decide whether the player actually owns enough currency.