So, here we are again, attempt number three at maintaining a blog. Let’s see if I can keep it up this time :)

I’ll be posting at least once a week, hopefully following Ayende’s method of posting about things I’m currently working on. I’ve moved my web hosting from a server in the US to an Australian server, and that’s sped up my response times to the site considerably. It makes a big difference to motivation when you’re not sitting around waiting for most of the time. Maybe I’m just impatient :P

Given this is a hello world post and I’m learning Haskell at the moment, I thought I’d try and craft one line of Haskell that does something interesting to come up with the classic “Hello World!”. Although, perhaps I should have tried to write a blog engine in one line of Haskell, it sure is terse enough :P

Here’s what I came up with:

foldr (\x y -> x++" "++y) "!"
  (map (\(x:xs) -> toUpper x:map toLower xs) ["HELLO", "WORLD"])

What does it do?

• It creates a list containing the strings “HELLO” and “WORLD”
• It maps a lambda on to the list so that the first character of each string in the list is uppercase and the rest of the characters are lowercase (giving us “Hello”, “World”)
• It does a fold right on the resulting list, with a lambda that concatenates each item in the list using a space as a separator and an exclamation mark as the intial seed

The result?

"Hello World !"

Ideally I’d have liked to not have the space in between “World” and “!”, but my haskell-fu isn’t good enough yet :)