Things I figured out about Haskell today

[maradydd]

• Maybe is the same thing as Kleene ? (the "zero or one" operator in regular expressions).
• A typeclass is the same thing as an STL concept, but a typeclass actually means it.
• instance means "We're going to make this data type an instance of this typeclass, and here's how."

Now if I can just get my head around monads, I'm set.

Comments

[neoliminal.livejournal.com]

Haskell scares me. In the same way that someone showed me you could make the number "1" into a function in Python. Although it's very entertaining that you can define a variable as infinity and only use the parts of infinity that you need at a given time.

[allonymist.livejournal.com]

Monads are weird. I can use them so long as I'm not thinking about how they work, and I can understand how they work so long as I'm not trying to use them.

[alexey-rom.livejournal.com]

See the paper "A comparison of C++ concepts and Haskell type classes": http://publications.lib.chalmers.se/cpl/record/index.xsql?pubid=72479

even the greeks had trouble with monads

[mohats.livejournal.com]

http://en.wikipedia.org/wiki/Monad_(Greek_philosophy)

so don't feel bad :-)

[m4dh4tt3r.livejournal.com]

How long have you been coding in haskell? I just started picking it up this week. I have experience with other functional languages, so a lot of the fundamentals are there. My motivation to pick up haskell is that our core developers where I am working is really into functional programming; one of the components we're developing is written in scheme.

? is not Maybe

[davidsarah.livejournal.com]

"Maybe is the same thing as Kleene ? (the "zero or one" operator in regular expressions)."

Nope. The types are significantly different. Kleene ? operates on sets of sequences; Maybe is a constructor for a discriminated union:

extension(T?) = extension(T) union {[]}.
extension(Maybe T) = {Some t | t in extension(T)} union {Nothing}.

This is not just nitpicking, honestly :-)

(You seem to have typeclasses right.)