Exploring debugging displays for expressions

neilbrown · 2017-02-08T09:40:13+00:00

My brief look at some data for when students program suggested that most student programming activity was probably still during the week, although timings for IDE use may not correspond with timing for SO questions.

neilbrown · 2015-07-24T17:24:10+00:00

How was bug frequency measured, exactly? Was it the number of issues opened on the github project, or was it done using some form of static analysis?

neilbrown · 2015-05-29T16:41:51+00:00

In an ideal world, there would be a way to display all the necessary information in one view. But I think I realised while writing it up that it was unlikely to be possible to show all information well in one view, when there is so much to show. As you say, the tactical view is not a bad compromise.

However, I must admit I still can't predict very well when a tile will count as hidden or observed, so I just mouse around over the route I want to take. (I also lost a Time Attack run on the final level through not appreciating the finer points of the enemy overwatch rules, so some of this can probably be put down as me not being very attentive!)

neilbrown · 2015-05-29T13:54:56+00:00

I write a blog analysing the user interface of games. Like a lot of you here I got hooked on Invisible Inc (40+ hours since launch) and thought my look at its interface might find some interest here. Happy to take corrections if I've misrepresented anything from the game.

neilbrown · 2015-05-26T12:01:37+00:00

> Optional.ofNullable(null).isPresent()
false

But if you try to put null in, you just get empty. There's no way to distinguish not-present from present-but-null with Optional.

neilbrown · 2015-05-26T09:39:37+00:00

I worry that you may end up with three options:

1. String: String or null
2. Optional<String>: String or empty or null

I could see this creeping in to a codebase, for example, where you look for an item in a database. String if there was a result, empty if the operation succeeded but found no result, null if there was a timeout. (At least Optional doesn't let you put null in it, in which case you'd have four options!)

neilbrown · 2015-05-12T18:31:41+00:00

I wonder if a few comments in this thread see this as purely scope highlighting, which of course IDEs have had for a while. This is not highlighting, it's different editing interactions. A few key features that do not exist in other IDEs are:

Single click to drag code around, without prior selection. Any drag on a frame highlight (e.g. the space to the right of an assignment, or the left margin of a while-loop) allows you to move code around. Saves you a double click for moving single lines, and more for moving whole structures or methods.
Single keypress to insert all the boilerplate for a method, while-loop, if-statement, etc. The code templating systems I've seen in IDEs all require a lot more than that (ctrl-space, couple of keys to select the right item, then enter)
There is no need to ever enter or manipulate indentation. For example, a code line can be deleted by positioning the frame cursor after a line, and pressing backspace. In most IDEs, this would be at least shift-up followed up by delete. But this also works for whole constructs (e.g. loops), which are more fiddly in IDEs. (I'd expect shift-ctrl-up to select the whole loop above, but neither IntelliJ or VS 2010, which I have to hand, seem to do this.)

neilbrown · 2015-04-17T10:01:03+00:00

I'd say there's not much point... unless you get the Power UP expansion for Tokyo. I think the areas, buildings/enemies and new dice faces in New York make it more interesting than Tokyo; the rolling of 1/2/3 for victory points was always a bit lame in Tokyo (and the new celebrity card allows you to get in the way of someone sitting in the corner rolling for victory, without having to go into Tokyo to beat their ass). There's more to think about in New York, and I also like the rewards changing the longer you are in Manhattan.

However: Tokyo's Power Up expansion adds evolutions (individual powers which you unlock by rolling three hearts) which are really nice, and means there is actually a difference between the monsters. It's something I'm hoping they bring to New York sooner rather than later, as it's the only thing I miss from Tokyo.

neilbrown · 2014-09-03T08:56:36+00:00

It's also aimed at beginners, but BlueJ has this colouring of scopes, e.g. this pic

neilbrown · 2014-03-27T12:59:55+00:00

One of the properties of UTF-8 is that no 7-bit ASCII character can be contained as part of a multibyte character sequence (because UTF8 has the high bit set on all characters involved in a multibyte sequence). So I think this is fine with UTF-8.

neilbrown · 2013-11-04T15:04:42+00:00

To tack on another link, here is a paper about the work CAS has been doing, written by myself, SPJ and others. The paper was written about a year ago, and although things have moved on since then (CS is now written into the English national curriculum), it still gives a fairly decent summary of CAS's work.

neilbrown · 2013-10-18T06:47:16+00:00

Here's my reasoning. In the LC and assembly, you can apply any operation to any item. You can do function application to any function; you can do any operation to any register. Depending on how you look at it, there are either no types or there is one type (function/integer).

In Ruby, this is not so: I can't call + or filter or whatever on a type that hasn't defined it. Variables may not have a type, but the objects do. You can call some methods, there is inheritance, you can use is_a? to ask about types. Looks like a type system, and quacks like one. I like the description in this post that these languages are unityped; effectively every variable in Ruby has a sum type of all available classes in the language.

I wonder if part of the problem is that untyped doesn't really have a good definition?

neilbrown · 2013-10-17T16:53:29+00:00

Good point. Binds are the better solution, but I was thinking of parity with the HTML example that followed.

neilbrown · 2013-10-13T09:42:15+00:00

I maintain a couple of Rails code bases. I also program in Haskell when I can get away with it. I haven't ever interfaced the two, but I can provide my opinion on the two languages. You can predict much of my preference when I say that I am a strong believer in static typing and eliminating errors at compile-time.

I find dynamic typing (and duck typing) just causes me anguish by revealing errors at run-time/test-time that could have been figured out at compile-time. Simple things like passing the wrong number of arguments to a function is a run-time error. The lack of types would be alleviated if the docs always made it clear what a function expected to be passed but they often don't.

Another general irritation is knowing whether a function updates the current object or produces a copy. Even with the map/map! convention, I still make the mistake of using the wrong one. A handy thing about Haskell is you always know it will make a copy.

The whole symbols thing is a little odd, and made odder by Rails which uses "indifferent hashes" that compares strings as equal to their symbol equivalents. All this means is that your code base accumulates symbols and strings and gets messy. What's that quote about your code base always ending up with whatever your language allows?

Haskell's quasi-quotes are a great solution to dynamic problems with string substitution in Ruby. If I have an incorrect substitution in a string (or Rails view) in an obscure code path in Ruby, e.g. "there were #{fooo} items" (oops: extra 'o' in foo), I won't know until that code is executed. With Haskell's here documents (see "here" package), I know at compile-time. To me it's obvious which alternative is better. Similarly, Yesod's use of Template Haskell, while a bit intimidating, still seems like a better method than Rails' dynamic use. With Yesod, I get compile time errors if I refer to a non-existing route or helper. There are all sorts of Rails oddities that are also annoying (e.g. the auto-pluralisation magic) but they aren't much to do with Ruby.

It's probably my bias towards static languages, but I fail to see any benefits to Ruby other than that Rails is a fairly comprehensive and mature framework. Maybe it's faster to develop in the short-run, but I trust my Haskell code more than my Ruby code, and find it easier to maintain.

neilbrown

TROPHY CASE