Lua but Functional

init.lua

local sub = string.sub
local concat = table.concat
local insert = table.insert
string.where = function(self, predicate)
    local buf = {}
    for i = 1, #self do
        local ch = sub(self, i, i)
        if (predicate(ch)) then
            insert(buf, ch)
        end
    end
    return concat(buf)
end

string.every = function(self, predicate)
    local buf = {}
    for i = 1, #self do
        insert(buf, predicate(sub(self, i, i)))
    end
    return concat(buf)
end

local array_metatable = {
    __index = table;
}

array = function(tab)
    return setmetatable(tab, array_metatable)
end

table.where = function(self, predicate)
    local buf = {}
    for i = 1, #self do
        local obj = self[i]
        if (predicate(obj, i)) then
            insert(buf, obj)
        end
    end
    return array(buf)
end

table.print = function(self)
    for i, v in next, self do
        print(i, v)
    end
end