Comments on: More Monads on the Cheap: Inlined fromMaybe

By: vacation blogger

vacation blogger — Thu, 17 Jul 2008 14:31:57 +0000

Thanks for this article, not sure I completely understand, but any help is appreciated.

By: used electric golf carts

used electric golf carts — Sat, 05 Jul 2008 04:45:38 +0000

Sorry mate, but you simply lost me at the end. Can you give us a URL for an intro to understand the whole topic? like a newbie manual or something?

By: Baxter

Baxter — Thu, 03 Jul 2008 09:58:13 +0000

What exactly is a code stylist?

By: Hogar

Hogar — Fri, 06 Jun 2008 18:16:25 +0000

Hi Oliver, thanks a lot for this in-depth article about this seldomly discussed topic.
It solved me quite a few problems i had with ruby.
Excellent work.
Best regards
Hogar

By: Marcus Westin

Marcus Westin — Fri, 21 Mar 2008 11:49:20 +0000

Thank you for the thorough discussion on a subject so seemingly trivial yet so prevalent in the coder’s day to day life.

May I offer a version of your compressed Ruby into what I consider a more idiomatic and cleaner Ruby?
# also accepts offer nil, offer.products nil loaded = offer && preloadAll(begin products = offer.products || []; products.map &:id));

Ruby way:
# also accepts offer nil, offer.products nil - Rubyier version loaded = preloadAll( (offer.products || []).map { |pr| pr.id } ) if offer

Reads much better I think.

Cheers!

By: oliver

oliver — Mon, 03 Mar 2008 16:05:08 +0000

I agree that thinking in types saves headaches. The point of the post was to extend code that worked only if products had type Array! (a non-nullable Array, to borrow ECMAScript 4.0 notation), such that it could handle Array? (analogous Haskell Maybe [], or Scala Option[List] — arrays aren’t the same as lists, but JavaScript arrays are used where Haskell and Scala use lists). The new code is only valid if the type of products is a nullable array. It won’t work if you throw arbitrary data at it. After all, if products could be anything, it might be an object with a length method, and then count would end up with the wrong type too.

By: Anonymous

Anonymous — Mon, 03 Mar 2008 14:47:11 +0000

Type checking will save you some headaches. For example:

var count = (products || []).length;

In the expression above, if products === Boolean true, an error will be thrown when trying to read the length property of a Boolean value. I’m all for short, sweet code, but better safe than sorry.

By: Michael Schuerig

Michael Schuerig — Thu, 28 Feb 2008 09:23:42 +0000

In Ruby it would be advisable to use Array(products) instead of (products || []). The former coerces its argument to an array, i.e., Array(nil) -> [], Array(1) -> [1], Array(1) -> [1].