I had the pleasure of studying with Paul Hudak, the creator of Haskell, and I remain highly intrigued by the language. I like your introduction a lot. A couple of things I would add in the relevance-to-Perl department:
- foldl is a lot like reduce in the List::Util module, which I believe will be a builtin in Perl 6.
- I believe there is a Perl implementation of lazy lists. Update: Per the reply below, it is Language::Functional.
- something I'm not thinking of
Also, I know you're trying to keep it reasonably short, but I think it would be really cool to show an example of constructing recursive polymorphic types, and the fact that you can have different data constructors with completely different type arguments. In other words, the fact that in Haskell you can implement large parts of your program logic just by the way you design your types.
I like the lazy factorial example. My favorite lazy expressions in Haskell were the fibonacci sequence:
fib :: [Integer]
fib = 1 : 1 : zipWith (+) fib (tail fib)
and the function for inserting commas in a string of digits according to standard notation:
inschar n c = foldr1 (\s1 s2 -> s1 ++ c : s2) .
map (take n) . takeWhile (not . null) . iterate (drop n)
commaize :: String -> String
commaize = reverse . inschar 3 ',' . reverse
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
- a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
| & || & |
| < || < |
| > || > |
| [ || [ |
| ] || ] |