local functools = {}

-- Lua implementation of the curry function
-- Developed by tinylittlelife.org
-- released under the WTFPL (http://sam.zoy.org/wtfpl/)

-- curry(func, num_args) : take a function requiring a tuple for num_args arguments
--              and turn it into a series of 1-argument functions
-- e.g.: you have a function dosomething(a, b, c)
--       curried_dosomething = curry(dosomething, 3) -- we want to curry 3 arguments
--       curried_dosomething (a1) (b1) (c1)  -- returns the result of dosomething(a1, b1, c1)
--       partial_dosomething1 = curried_dosomething (a_value) -- returns a function
--       partial_dosomething2 = partial_dosomething1 (b_value) -- returns a function
--       partial_dosomething2 (c_value) -- returns the result of dosomething(a_value, b_value, c_value)
function functools.curry(func, num_args)

    -- currying 2-argument functions seems to be the most popular application
    num_args = num_args or 2

    -- helper
    local function curry_h(argtrace, n)
        if 0 == n then
            -- reverse argument list and call function
            return func(functools.reverse(argtrace()))
        else
            -- "push" argument (by building a wrapper function) and decrement n
            return function (onearg)
                return curry_h(function () return onearg, argtrace() end, n - 1)
            end
        end
    end

    -- no sense currying for 1 arg or less
    if num_args > 1 then
        return curry_h(function () return end, num_args)
    else
        return func
    end
end

-- reverse(...) : take some tuple and return a tuple of	elements in reverse order
--
-- e.g.	"reverse(1,2,3)" returns 3,2,1
function functools.reverse(...)

    --reverse args by building a function to do it, similar to the unpack() example
    local function reverse_h(acc, v, ...)
        if 0 == select('#', ...) then
            return v, acc()
        else
            return reverse_h(function () return v, acc() end, ...)
        end
    end

    -- initial acc is the end of the list
    return reverse_h(function () return end, ...)
end


function functools.map(func, tbl)
    local newtbl = {}
    for i,v in pairs(tbl) do
        newtbl[i] = func(v)
    end
    return newtbl
end

function functools.filter(func, tbl)
    local newtbl= {}
    local index=1;
    for i,v in pairs(tbl) do
        if func(v, i) then
            newtbl[index]=v
            index = index + 1
        end
    end
    return newtbl
end

function functools.search(func, tbl)
    for i,v in pairs(tbl) do
        if func(v, i) then
            return i
        end
    end

    return 0
end

return functools