Hey there. There's an updated html5 book version, if you want.

On day 4 we reviewed typeclass laws like Functor laws and used ScalaCheck to validate on arbitrary examples of a typeclass. We also looked at three different ways of using Option as Monoid, and looked at Foldable that can foldMap etc.

A fist full of Monads

We get to start a new chapter today on Learn You a Haskell for Great Good.

Hey there. There's an updated html5 book version, if you want.

Yesterday we reviewed kinds and types, explored Tagged type, and started looking at Semigroup and Monoid as a way of abstracting binary operations over various types.

I've gotten a few feedbacks. First, paulp suggested that I could use companion type like Option.type for our kind calculator. Using the updated version, we get the following:

scala> kind[Functor.type]

Hey there. There's an updated html5 book version, if you want.

Yesterday we started with Functor, which adds map operator, and ended with polymorphic sequenceA function that uses Pointed[F].point and Applicative ^(f1, f2) {_ :: _} syntax.

Kinds and some type-foo

Hey there. There's an updated html5 book version, if you want.

Yesterday we reviewed a few basic typeclasses from Scalaz like Equal by using Learn You a Haskell for Great Good as the guide. We also created our own CanTruthy typeclass.

Functor

LYAHFGG:

And now, we're going to take a look at the Functor typeclass, which is basically for things that can be mapped over.

Hey there. There's an updated html5 book version, if you want.

How many programming languages have been called Lisp in sheep's clothing? Java brought in GC to familiar C++ like grammar. Although there have been other languages with GC, in 1996 it felt like a big deal because it promised to become a viable alternative to C++. Eventually, people got used to not having to manage memory by hand. JavaScript and Ruby both have been called Lisp in sheep's clothing for their first-class functions and block syntax. The homoiconic nature of S-expression still makes Lisp-like languages interesting as it fits well to macros.

Recently languages are borrowing concepts from newer breed of functional languages. Type inference and pattern matching I am guessing goes back to ML. Eventually people will come to expect these features too. Given that Lisp came out in 1958 and ML in 1973, it seems to take decades for good ideas to catch on. For those cold decades, these languages were probably considered heretical or worse "not serious."

Looking back to our Scala community, it pains me to see people jeering at Scalaz. I'm not saying it's going to be the next big thing. I don't even know about it yet. But one thing for sure is that guys using it are serious about solving their problems. Or just as pedantic as the rest of the Scala community using pattern matching. Given that Haskell came out in 1990, the witch hunt may last a while, but I am going to keep an open mind.

Yesterday we've created two stage actors so the agent can play against the player. To make things more interesting, attacking was implemented which sends junk blocks to the opponent.

unfair advantage

Yesterday we've written a test harness to automate scripted games to tune various components of the heuristic function. The overall performance improved from 7 +/- 2 lines to 34 +/- 18, almost 5x improvement.

HAL moment

Yesterday we expanded the search tree of the tetrix-solving agent into second piece. Although the quality of the game it is able to play has improved, there are some more room for tweaking.

scripting

Yesterday we got the tetrix-solving agent to play a better game by fixing the heuristic function and evaluating 36 possible positions of the current piece.

stop watch

Let's start by creating a function to measure the time it takes to run a segment of code:

  private[this] def stopWatch[A](name: String)(arg: => A): A = {
    val t0 = System.currentTimeMillis
    val retval: A = arg
    val t1 = System.currentTimeMillis
    println(name + " took " + (t1 - t0).toString + " ms")
    retval
  }