miércoles, 21 de mayo de 2014

multiple value return in lua

Lua functions can return multiple values, and the language will natively assign them to the variables on the other side of the equal sign.

local a, b = (function() return 1,2 end)()
print(a,b) => 1     2
That's fine, but when things get a bit more tricky is when the values are not returned in tail call position.
local a, b = (function()
               local res = (function() return 1 , 2 end)()
               return res
print(a, b) =>  1    nil
The catch is that lua assigns the 'rest' of the values only to the last element of tables, or argument lists. If we want to wrap a function into another while not being in tail position, we have to use a little trick. This trick is unpack.
local a, b = (function()
               local res = {(function() return 1 , 2 end)()}
               return unpack(res)
print(a, b) =>  1    2

jueves, 8 de mayo de 2014

Presenting Eva

I've hacked a tiny little lisp interpreter in lua, and I called Eva, for obvious reasons.

It's not pretty, it's not complete at all. Hell, it doesn't even have strings, you can't call native lua functions, and there are no conses (although you could get them using functions for that).

The whole point of it was to have some fun implementing a tiny lisp-like thingie, and to make it in lua, which is a language that I like quite a lot (although some of its table missfeatures make me cry sometimes)

Without further ado, Eva .

miércoles, 7 de mayo de 2014

erc makes you faster at jokes!

Hi, today's post is a simple sinppet I wrote to ease the pain of looking for recurrent references on the internet.

At work we use IRC heavily (it's our main channel for comunication). As you know,every platform or channel of comunication has its own processes and joke (slightly related (but interesting nonetheless): The medium is the Massage ) . So IRC is mostly about sending links to gifs and to funny images, and funny images with captions in them.

It's so simple that it doesn't even need explanation. You just have to know that all defuns named "erc-cmd-SOMETHING" will be automatically callable from erc as a /something.

(defun erc-cmd-MEME (wat)
  "Fetch links from the alist of knowledge"
  (let ((h '(("trap" "http://4.bp.blogspot.com/-ae1ZRrrjs8c/Th0rz7ZvogI/AAAAAAAAANU/QM2WW-LNZXY/s1600/original.jpg"))))
    (erc-send-message (cadr (assoc wat h)))))

Combined with erc-image.el, it makes a really nice IRC experience :)