tangus

Probably vector-drawn diagrams are rendered into bitmap images for the EPUB version.

I guess they wanted to keep working on their slides (at least for the moment) and not be forced to go debugging. Sadly, the hang was deterministic, so they didn't have another option.

Aren't they basically saying opposite things? Perlis is saying "don't choose the right data structure, shoehorn your data into the most popular one". This advice might have made sense before generic programming was widespread; I think it's obsolete.

Everything they have is downloadable. Go to their home page and follow the links.

Everybody carries a gun in Heinlein stories, so those terrorists will be quickly dealt with by armed citizens, thus confirming the superiority of Libertarianism.

For the record, if you want to avoid the creation of intermediate arrays, you can:

    lst.lazy.grep(Array).flat_map(&:itself).sum

Not as clear, because the standard library doesn't have a `#flatten` method for lazy enumerators.

But the point is the interface, not the implementation. Efficiency doesn't mandate assembly-like DSLs. Your interface could be as clear and clean as Ruby's and produce fast, inlined code by the power of macros. Ruby doesn't have macros, so chaining lambdas is the best it can do.

Ruby also has call/cc. None of the iterating methods has any provision to make them "safe" from it. They aren't safe from modifications to the iterated collection either. I think it makes sense; being forced to accumulate using only linked lists and having to be constantly on guard to support a rarely used quirky feature is a bad tradeoff IMO.

Careful. Seeing how I was downvoted for asking, it looks people here don't want that information to spread.

It may be somewhat awkward; zipping collections to iterate over them in unison makes the first one (the sender) seem special, while it not necessarily is. And accumulating more than one value isn't always straightforward; you usually have to reduce explicitly. But it's so much better in the general case!

Like the example you showcase your macro with. In Ruby it would be:

    lst = [[1, 2], :dud, [3, 4], [5, 6]]
    lst.grep(Array).flatten.sum
    => 21

You can see what it does at a glance, you don't have to immerse yourself inside the directives to follow the logic. And when you can't do that, declaring iterators and accumulators outside a loop and then iterating and accumulating "by hand" yields code not so different than your more complex examples.

  def partition (arr)
    yes = []
    no = []
    arr.each do |elt|
      if yield elt
        yes << elt
      else
        no << elt
      end
    end
    [yes, no]
  end

Looping in Ruby is the opposite of awful. You only have to define an `#each` method in your class and include the `Enumerable` module, and you get a plethora of composable methods to iterate and accumulate in every which way. I find it nothing short of brilliant.

It's paywalled, please provide a workaround.

In the late 90's I had a girlfriend who worked for a shop that made web pages in COBOL. I thought those were COBOL's death throes, but apparently I was mistaken...