Posts filed under “Uncategorized”
Perl6 ternaries and Haskell Maybe
Just a quick post as I've not had a lot of time to play with Haskell just recently. This morning I noticed Jonathan Lang's post to perl6-language asking if the ternary operator ?? !! could be turned into two binary operators. I thought this had been discussed some time back, but apparently not. Audrey commented […]
Chapter 7: Trees
I start off confidently, typing in the first example into my scratch file: > data Tree = Leaf a | Branch (Tree a) (Tree a) Of course, ghci complains bitterly, and strangely Prelude> :l 7.hs [1 of 1] Compiling Tree ( 7.hs, interpreted ) 7.hs:5:19: Not in scope: type variable `a' 7.hs:5:36: Not in scope: […]
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 […]
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 […]
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" […]