Thoughts Heap

Birdseye Software: conduits, reactive extensions (rxjs) and time

Fri, 17 May 2013 13:35:52 -0700

Birdseye Software: conduits, reactive extensions (rxjs) and time:

Recently we have been working on a project that use the Reactive Extensions library (rxjs) on the front-end and Conduit for handling event and IO streams in Haskell. In practice, working with rxjs is similar to using Conduits/Iteratees/Pipes in Haskell. Of the many benefits [pdf] of rxjs,…

Reluctant, Lazy Blogger: :) @romanandreg and I just implemented animated replay of...

Thu, 31 Jan 2013 12:23:32 -0800

Reluctant, Lazy Blogger: :) @romanandreg and I just implemented animated replay of...:

tavisrudd:

:) @romanandreg and I just implemented animated replay of event-sourced UI test fixtures http://rxtest.dentalle.com/#fixture:separate_post_metals::animate vs http://rxtest.dentalle.com/#fixture:separate_post_metals which just jumps to the end state and highlights the last change.

The fixtures…

Great Work

Last week I implemented an emacs plugin called golden-ratio.el...

Sat, 13 Oct 2012 11:23:03 -0700

Last week I implemented an emacs plugin called golden-ratio.el to resize the window I’m editiing in, the size to which it is resized follows the golden ratio measures, hence the name, I’m leaving this image here to use it later in github/forums.

chiguire: Somebodies, por Gotye. Un remix de videos amateurs...

Mon, 13 Aug 2012 15:59:44 -0700

chiguire:

Somebodies, por Gotye. Un remix de videos amateurs covers de Somebody That I Used To Know.

The power of collaborative work, is just amazing…

Installing emacs24 in precise pangoling

Wed, 01 Aug 2012 16:25:00 -0700

This is specially useful in vagrant machines

Install utility to add apt sources easily:
sudo apt-get install python-software-properties
Add sources that contains emacs24
sudo add-apt-repository ppa:cassou/emacs
Update the apt source list and install emacs24-nox (for emacs without X)
sudo apt-get update; sudo apt-get install emacs24-nox

Done.

Photo

Fri, 22 Jun 2012 11:13:58 -0700

"Udacity isn’t concerned with students who fall short. Its creators are busy trying to help those who..."

Fri, 08 Jun 2012 10:01:00 -0700

“Udacity isn’t concerned with students who fall short. Its creators are busy trying to help those who ace every triple-gold-star problem and never miss a quiz—the young men in Lahore, Beirut, and Caracas who haunt Internet cafes and spend hours engaging in jargony repartee about elegant solutions on the Udacity message board. These are the people that Udacity hopes to help recruit to talent-hungry dot-coms like Google and Amazon”

- Funny how they mention Caracas as one of the places with people with low resources…

From this blogpost

Installing virtualbox guest additions

Mon, 04 Jun 2012 10:41:09 -0700

Whenever I upgrade the version of my virtualbox env, I always run through the annoying warning given by vagrant, saying that the virtual machine doesn’t have a matching version to the virtualbox-guest-additions.

In order to solve this issue, I always follow the steps given in this blogpost.

I re-post this steps over here for my personal records…

Installing Oracle Java 7 on Ubuntu Precise Pangolin

Sun, 03 Jun 2012 20:56:40 -0700

This is specially useful in vagrant machines

Install utility to add apt sources easily:
sudo apt-get install python-software-properties
Add sources that contains oracle-java-7
sudo add-apt-repository ppa:webupd8team/java
Update the apt source list and install java’s oracle version
sudo apt-get update; sudo apt-get install oracle-jdk7-installer

Done.

"Success is when you’ve failed so much that you start to fail at failing."

Sat, 07 Apr 2012 09:46:09 -0700

“Success is when you’ve failed so much that you start to fail at failing.”

- @bengrue

"You’re always coding with two other programmers: past you and future you. Past you is an..."

Wed, 04 Apr 2012 14:58:40 -0700

“You’re always coding with two other programmers: past you and future you. Past you is an imbecile, but future you is a liar.”

- @bmf

Http Authentication failing with Devise < 2.0 and Rails 3

Wed, 14 Mar 2012 17:43:38 -0700

If you are pulling your hair out because Devise’s HTTP authentication doesn’t seem to work after an hour or so, don’t despair, I have the solution for you…

If you can see a warning in your log saying something like:


DEPRECATION WARNING: ActiveSupport::Base64.decode64 is deprecated. Use Base64.decode64 instead.

It is not just a warning, the HTTP Auth will fail miserably if you have this issue. The simple solution is to use a Devise version that has this commit applied, preferably version 2.0.4 on your Gemfile would do

You welcome.

"When you don’t have resources, you become resourceful."

Tue, 13 Mar 2012 13:40:35 -0700

“When you don’t have resources, you become resourceful.”

- K. R. Sridhar.

Is Clojurescript using calcdeps.py?

Mon, 05 Mar 2012 20:13:49 -0800

The answer is no…

Currently I’m reading the Google Closure: The definitive guide, in order to better use the Clojurescript (cljs) language .

On of the things I was a confused about, was on how cljs managed to handle dependencies on the cljs files, as I didn’t see any options regarding the calcdeps.py on the cljs.closure/build function.

After failing on finding a nice Google search result that would help me on this, I went straight to the source code of cljs.closure/build looking for answers.

The current status is that the calcdeps.py script provided by Google Closure was discarded altogether by an implementation of it in Clojure. This has some limitations given that you won’t be able (as far as I’m concern) to use different --output-mode as given by the calcdeps.py script.

The only options available are either, passing an :optimizations key to the cljs.closure/build function with a value of :whitespace, :simple or :advanced, or don’t pass any at all, in the latter case the result would be a deps file, the same the --output-mode=deps would return, which is very useful on development mode.

If you want to know more, I really suggest checking out the source of the cljs.closure namespace, it is really understandable code and it will answer a lot of questions in the comments.

Vancouver's Clojure Club is ALIVE!

Wed, 01 Feb 2012 12:10:23 -0800

Vancouver's Clojure Club is ALIVE!:

Some friends and myself decided to formalize a study group we were having for learning Clojure, at this point I think there is enough people that could comfortably work on open source projects.

The idea is to join and share projects as a group to gain more feedback from others, this way if a group checks and uses the libraries instead of individuals this libraries will definitely get more traction.

Hopefully this initiative will bring really great OS projects to life.

"Most of the biggest problems in software are problems of misconception."

Fri, 02 Dec 2011 09:57:43 -0800

“Most of the biggest problems in software are problems of misconception.”

- Rich Hickey.

Haskell's Show and pretty printing bad practice

Wed, 30 Nov 2011 06:02:06 -0800

Most of times when I was coding Haskell code, I always implemented the Show classtype whenever I wanted to print things on the screen in a nice and fashionable way.

It seems however this is a really bad practice that hasn’t been taught enough in the Haskell community. I discovered this in a StackOverflow question that had nothing to do with pretty printing, but the discussion led to that¹.

A user named Matt Fenwick suggested that for whatever reason the guy who asked the question shouldn’t implement the Show classtype, later on I started to comment:

Me: Why not declare Show classtype for the Expr? just curious?

hammar: Show is meant as a form of lightweight serialization. It’s not meant for pretty-printing, although people often abuse it that way. In particular, if a Read instance is also defined, one should be able to expect that read . show is the identity function.

After that realization, I went out and looked over for different pretty printing solutions in Haskell. This was quite frustrating, for some reason I didn’t find any library that would define pretty printing functions for basic containers like List, Set, Map.

The closest I’ve found to an out of the box pretty printing solution was the pretty-show package. However this doesn’t create a new classtype for pretty printing, making it really limiting IMO.

There is also the well established pretty package, This one provides combinators to create pretty printing functions easily, however, it doesn’t provide a classtype or a default implementation for the containers mentioned above.

Lastly the most promising package I’ve found is called GenericPretty. This one provides a classtype for pretty printing and implements some Prelude ADT, however no containers whatsoever and no combinators for generating pretty printing.

In conclusion, the pretty printing solutions are so, so… yet there is potential for something new raising up in the future.

¹ | Because of this the title was later changed to Show and Pretty-Printing

Clojure's repeatedly gotcha

Mon, 28 Nov 2011 07:05:00 -0800

When using Clojure’s repeatedly function to read lines from a terminal, or when trying to do IO of some sort, the behavior won’t be as expected

This is because repeatedly instead of calling the action n times, it generates a lazy seq for each time the action function gets called. Given that it is a lazy seq, if you don’t force the evaluation of the list, all but the first element will not be executed.

In order to avoid this, you have to use the dorun function, this is going to force evaluation for each element on a lazy seq, and it will discard the result of the seq altogether, this is because this function is expecting the action body to be for side-effects only

if you come from Haskell land, the idiom (dorun (repeatedly n body-fn)) would be the equivalent to call the function repeatM_.

An example:

Vim's Fugitive's "Error detected while processing function 51_Commit"

Tue, 08 Nov 2011 19:01:00 -0800

At a random time on my development cycle, I was using the awesome Fugitive plugin developed by Tim Pope, and I got the following strange error:


Error detected while processing function 51_Commit:
line   52:
E480: No match: `=msgfile`
Press ENTER or type command to continue

After some googling, I found out the reason was that I installed just a few days ago the also awesome ctrlp plugin. When you were setting up ctrlp, you did something like this:


set wildignore=*/.git/*,*/.hg/*,*/dist/*,*/cabal-dev/*

Well… it seems Fugitive plugin doesn’t like that very much, if you remove the git portion from that setting, Fugitive will work as expected again

Thanks Interwebz

"The distinction between mechanism and policy is one of the best ideas behind the Unix design. Most..."

Tue, 25 Oct 2011 14:52:54 -0700

“The distinction between mechanism and policy is one of the best ideas behind the Unix design. Most programming problems can indeed be split into two parts: “what capabilities are to be provided” (the mechanism) and “how those capabilities can be used” (the policy). If the two issues are addressed by different parts of the program, or even by different programs altogether, the software package is much easier to develop and to adapt to particular needs.”

- Jonathan Corbet, Greg Kroah-Hartman, Alessandro Rubini on Linux Device Drivers, 3rd Edition