Archive for May, 2007
Chapter 6: Shapes III: Perimeters
(Haven't really had much time for Haskell this week – I had set myself the task of comparing some versions of SOE exercises, but will get back to that as soon as I can. In the mean time, another (shortish) post in the regular series…) The first part is straight forward enough. We create a […]
Lambdacamels, slime, and a syphilitic stoat.
1. In which a challenge is thrown, but there is a spanner in the works! Haskell suddenly became “important†in the Perl community when Audrey Tang started to blog about Pugs, the prototype version of the Perl 6 interpreter/compiler. So, when I started looking at Haskell, I did so with another Perl-monger, larsen, one of […]
Trigonometry reprise
I whined on IRC about my inability to do simple trig and dakkar kindly took me through the basics of a cosine. So I sat down later to look again at an exercise I'd skipped: 2.2 to defined the function: > regularPolygon :: Int -> Side -> Shape> But I realised that I still couldn't […]
Chapter 5: Polymorphic and Higher-Order functions
This is an interesting chapter, working on the higher order functions rather than actually drawing shapes. It covers: Polymorphic types Principal type – this is an interesting idea, the type inferencer can determine that something works on an Int, say, or “Number stuffâ€, or “just any stuffâ€, or “a list of stuffâ€. Too general and […]
Chapter 4: Shapes II, drawing Shapes (short)
We are presented with some coercion functions and asked Ex 4.1: Why is inchToPixel x not defined as 100 * round x ? It is instead defined as round(100 * x). This is because if rounding was done on the input parameter, then whether it was, say, 1.01 or 1.99, the answer would be the […]
SOE, Erlang, etc.
David Tran got in touch to say he's also working his way through SOE, and he's posting on http://davidtran.doublegifts.com/blog/, where he's mainly posting solutions, looks good! I discussed some answers on irc with Apocalisp, who has some very subtle versions of regularPolygon and isConvex. I may, though I still find doing proofs painful-and-not-really-fun try to […]
Meta: Shaving the Haskell blog yak
HTML is all very well and good, but frankly, I'm too lazy to mark up my&,<,> characters all the time by hand, at least withincode. I used the POD formatter pod2html for a couple of earlyposts. It's OK, it basically has a concept of "This is a normal textparagraph, and this is a code paragraph" […]
Chapter 3. SOE
If I found the exercises in chapter 2 a little hard, the fact that thereare only two of them in this chapter should have been a warning… Amusingly, Hudak suggests that the module SOEGraphics will notevolve, as it is designed for the textbook, however, as it happens, ithas changed its API in a significant way […]
Notes on Chapter 2 of SOE
Hello Planet A couple of weeks back, I got an email from Antti-Juhani who'd just processedmy request to have this blog added to planet Haskell. He pointed outthat I seemed to have gone awfully quiet… Basically, not had a lot oftuits recently, but now I'm working through SOE a bit more seriously,here are my notes […]