-- quotation.lua
local function quotation_call(quote, env)
    if rawget(quote, "namespace") then env.namespace:push(quote.namespace) end
    for _, item in ipairs(quote.body) do
        local typ = type(item)
        if typ == "number" or typ == "boolean" or typ == "string"  or (typ == "table" and item.type == "quote") then
            env.data:push(item)
        else
            item(env)
        end
    end
    if rawget(quote, "namespace") then env.namespace:pop() end
end

-- gilded.lua
builtins["call"] = function(env)
    env:assertHeight(1)
    local quote = env.data:pop()
    return quote(env)
end

-- snipped --

local env = enviroment.new()
for _, item in ipairs(program) do
    local typ = type(item)
    if typ == "number" or typ == "boolean" or typ == "string"  or (typ == "table" and item.type == "quote") then
        env.data:push(item)
    else
        item(env)
    end
end