> As a fellow beginner (learning for well over a year, on and off), I'll
> show a way I would do it:
> isAnagramOf =: -:&:(-.&' '@:/:~@:tolower)
I'd like to add some advice for J newbies:
During the first two months (perhaps even two years, or two
decades), resist any urge to put more than five things to
the right of an =:
Factor out every small sub-unit you can. That simplifies debugging A LOT.
Taking the above:
normalize_string =: -.&' '@:/:~@:tolower
isAnagramOf =: -:&:normalize_string
You certainly get the idea. As you can see, the -.&' '@:/:~@:tolower
has still way more than five words (namely 8) and I'm not really sure
that its author is aware that the ~ refers to not just the /: but
to the whole -.&' '@:/: pipeline to its left.
Again, smaller sub-units help to avoid such accidents:
sort =: /:~
de_space =: -.&' '
normalize =: de_space@sort@tolower
isAnagramOf =: -:&normalize
Almost every time, these tiny sub-units provide something useful even
beyond of the current context ("anagrams"). They are certainly easier
to test/verify.
It also makes reasoning about the ranks of the components easier.
In consequence, it becomes easier to make an educated selection
between @ vs @: or & vs &: -- much better than to stick blindly
to some mysterious rule of thumb.
Martin Neitzel
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
