Just another lambdabananacamel,

In the last post, I mentioned that we might be able to improve the performance of our sort using a "http://en.wikipedia.org/wiki/Schwartzian_transform". This basically involves precaching the expensive calculation (in this case, length), sorting by the cached value, then taking just the original values. Let's test with a list of words: words "If on a winter's night a traveller" So instead of [...]

I've been away for a while from Haskell so I thought I should do some revision and really get my head around Monads. While I plodded through the wonderful "meet the monads" tutorial, I decided that the best way to learn would be to do. By implementing Monads in Perl. I'd highly recommend trying to implement [...]

Thanks to Chris and Thom for organising the recent GeekUp Liverpool talks.  The evening started well with Martin Owen's very interesting talk on justifying Erlang, and why FP is going to become a major factor in tomorrow's concurrency-oriented world.  I demonstrated the wisdom of always saving a copy of your talk in PDF to a [...]

Thom has posted the details of the next Liverpool geekup, Tuesday May 27th at 3345 Parr Street. Last time, I admitted to programming in Perl and got ribbed about it being unreadable.  Fueled by the fervour of the righteous (and maybe a pint or two of Cains bitter) I volunteered to do a talk on [...]

On #moose, the channel for a popular modern dialect of Object Oriented Perl, Debolaz asked: <Debolaz> Is there a simple way to produce an array of array like [[1..4],[1..4]] without having to specify the [...]

This morning, Ranguard asked an interesting question on #london.pm: 11:27 <@ranguard> What's the best way of finding the common root of two paths, e.g. for /a/b/c/d/e, /a/b/c/1/2/3 I want /a/b/c/ returned, [...]

Greg confessed on #london.pm to having written a average function in Perl in FP style... recursively. I asked him about this, as a perfectly good average function (using List::Util would be: sub avg { sum(@_) / @_ } which is perfectly fine FP style too. As far as I could understand it, he was reducing [...]

Some interesting comments on yesterday's Haskell post.  I thought I'd write this in Perl to compare.  Of course, we don't have an "inits" function in the standard library, but that's easily written:#!/usr/bin/perluse strict; use warnings;use Data::Dumper;my %hash = ( "key1" => 1, "key2" => 2, [...]

Haskell's prelude has a function words that splits a string by spaces. Prelude> words "nice cup of tea" ["nice","cup","of","tea"] Apparently the question comes up quite regularly on irc or haskell-cafe as to why this function is specialised to split only on whitespace. Perl's split, for example, can split on any character, or indeed string or regular expression. As quicksilver [...]

For some time I've been wanting to implement the Enfilade, a really cool data structure discovered by the Xanadu people among others. It's like a balanced tree, except that it's indexed relatively rather than absolutely - making it ideal for things like text editor buffers, as you can insert and delete with impunity, knowing that the changes to the address [...]