[Haskell-cafe] PrefixMap: code review request
robdockins at fastmail.fm
Mon Feb 27 15:11:44 EST 2006
On Feb 27, 2006, at 2:30 PM, David F.Place wrote:
> I'm a newish Haskell hacker with way too much experience hacking
> Lisp. At first, I found my Haskell code looking very lisp-y. I
> think my code is becoming more idiomatic haskell. I would be very
> grateful to anyone who would take a glance at the code below and
> point out any un-idiomatic usages that jump out. It's a small
> module from a program which looks for palindromes in a list of
> words. Thanks very much.
> partList :: Ord k => [([k],v)]->[k]->[(k,[([k],v)])]
> partList pairs alphabet = reverse . fst $ foldl' f (,pairs) alphabet
> where f (result,pairs) l = (result',rest)
> where (part,rest) = span ((==l) . head . fst) pairs
> result' = if null part
> then result
> else (l,part):result
I don't think I've ever seen nested "where"s before ;-) I'd probably
avoid that; it's really hard to read. If your function is
sufficiently complicated that it needs its own "where" clause, you
should probably just promote it to the top level. If it is truly
internal, you can avoid exporting it with the module export list.
> searchMap :: Ord k => (v -> vv) -> [k] -> PrefixMap k v -> [vv]
Humm... double "v" seems like a pretty poor choice for a type
Just a couple of general comments:
-- you don't seem to like horizontal whitespace much. I know, I
know, whitespace placement can be a highly personal thing, but I find
most haskellers usually use a bit more horizontal whitespace,
particularly in function signatures. The arrow is almost always
written with surrounding spaces. I personally like space after
commas in tuples and lists. Several of your list comprehensions
would also be easier to read with a bit of whitespace. I also tend
to like '=' signs lined up in a column for lets, pattern function
definitions and wheres.
-- Nested tuple and lists types are pretty hard to read. In your
code [([k],v)] appears a lot. Consider defining a type alias for it.
Speak softly and drive a Sherman tank.
Laugh hard; it's a long way to the bank.
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