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I greatly enjoyed Douglas Crockford's recent lecture series, particularly the talk which covered the history of programming languages. I'd like to learn about this subject in more detail.
Consider this question language agnostic. I'm not interested in books that teach programming. I'm interested in books which discuss decisions made during the design of one or more languages.
Following three are IMO the must-read books for any programming langauges junky :)
Project Oberon by Niklaus Wirth
Language Implementation Patterns by Terence Parr
Programming Language Pragmatics by Michael Scott
Every 15 years, the ACM puts on a History of Programming Languages conference (affectionately known as HoPL). The proceedings are of exceptionally high quality, and are available, unfortunately only behind the ACM paywall. (However, if you access them from a university, college or school IP address, you should be able to access them.)
For HoPL-III (2007), Guido van Rossum wanted to submit a paper about Python, but he wasn't able to meet the review requirements in time, so he published it in form of a blog instead.
Several presenters also published their papers for free, in addition to the official conference proceedings. Also, several presenters gave the same talk again, at a different venue. For example, Guy L. Steele, Jr. and Richard P. "Dick" Gabriel repeated their "50 in 50" talk (which, as you can imagine if you've ever seen a talk by Guy Steele or Dick Gabriel, is not really a talk, more like multimedia performance art crossed with poetry slam meets Broadway), which presents 50 programming languages in 50 words each.
As #Missing Faktor mentioned above, not only Project Oberon, but all of Niklaus Wirth's languages are tremendously well documented: Algol-60, Algol-X, Algol-W, Pascal, Modula-2, and Oberon.
Structure and Interpretation of Computer Programs. I have a print copy, but it's now available online for free:
http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-4.html#%_toc_start
The Design and Evolution of C++
http://www2.research.att.com/~bs/dne.html
Programming Language Essentials
Rationale for the Design of the Ada Programming Language:
http://www.amazon.com/Rationale-Design-Programming-Language-Companion/dp/0521392675
Although the book discusses the original version of the language, it still makes interesting reading. For each design decision, rationale and discussion is included, both from the point view the programmer and compiler implementer.
"Architecture of Concurrent Programs", by the late Per Brinch Hansen, includes a good overview of the design and rationale for his Concurrent Pascal language, which added monitors (and other things) to his Sequential Pascal, a proper subset of Pascal.
The big thing missing from Sequential Pascal is pointers. However, given the restrictions intended to be placed on Sequential Pascal programs, everything you can do with a pointer you can also do with an array index, and in a more secure way, "secure" in the sense that it is impossible (and checked by the compiler!) to do illegal things.
I often read about the importance of readability and maintainability. Or, I read very strong opinions about which syntax features are bad or good. Or discussions about the values of certain paradigms, like OOP.
Aside from that, this same question floats about in my mind whenever I read debates on SO or Meta about subjective questions. Or read questions about best practices and sometimes find myself or others disagreeing.
What role does subjectiveness play within the programming realm?
Sometimes I think it plays a large role. Software developers are engineers in a way, but also people. A large part of programming is dealing with code that's human readable. This is very different from Math or Physics or other disciplines with very exact and structured rules. Here the exact structure and rules are largely up in the air, changeable on a whim, and hence the amount of languages in existence. And one person may find one language very readable, and another person may find their own language the most comforting.
The same with practices. One person may not like certain accepted practices. I myself find splitting classes into different files very unreadable, for instance.
But, I can't say rules haven't helped in general. Certain practices have and do make life easier. And new languages have given rise to syntax and structure that make life easier. There's certainly been a progression towards code that is easier to read and maintain even given a largely diverse group of people. So maybe these things aren't as subjective as I thought.
It reminds me, in a way, of UI design. Certainly it's subjective, but then there's an entire discipline involved in crafting good UI and it tends to work.
Is there something non-subjective about the ideas behind maintainability, readability, and other best practices? Is there something tangible to grasp when one develops a new language or thinks of new practices?
Arguably your question is really about the distinction between programming, which is mathematical, algorithmic and scientific, and software engineering, which is subjective, variable and human-focused.
Great programmers are not necessarily great software engineers, and vice versa. The two skillsets, while not exclusive by any means, have less overlap than they appear at first. Their relative importance depends a lot on the project: a brilliant programmer working alone can turn out amazing examples of technical genius, and it doesn't matter that nobody else can understand or maintain it, because he's not going to share the code anyway. But move into an enterprise environment -- like corporate in-house software development -- and I'll gladly trade you ten "cave troll" geniuses for a mediocre programmer who understands the importance of readability and documentation.
It's been my experience that the world needs great software engineers more than it needs great programmers. Relatively few people in this day and age are writing software which is truly performance-critical (OS kernels, compilers, graphics engines, realtime embedded systems, etc), and the Internet allows mediocre programmers to quickly grab algorithmic solutions for problems they couldn't solve alone. But nearly everyone writing professional code has to work within a team. And team productivity rises and falls dramatically on the ability of its members to communicate effectively and distribute workload efficiently, two skills which are highly subjective and impossible to prove by rigid formula.
Most software engineering principles are built on experience rather than objective law. Much like the social sciences, we study, learn, adapt and apply -- but with no real guarantees of outcome. All we can say is that some things seem to work better than others in most groups.
I think, a lot of it is necessarily determined by how much our mind is able to process at one time. So it comes down to how much the language and tools enable a team or a developer to break down the problem into chunks that are meaningful by themselves, but not so large that it becomes too hard to grasp them. The common theme is the art of organizing information (in this case, the code, the logic, ...) But that's not so different from Maths or Physics, by the way.
Just as the best authors borrow from many styles, the best programmers keep a huge range of patterns in their mental arsenal. Slavishly following a few patterns and adhering to some absolute truth is both lazy and dangerous.
Put it another way, the day we rely on robots for code review is the day I quit.
It all depends on your point of view :-)
But to answer your questions, I think one way to view subjectivity is to recognize that software languages, tools, and best practices are a shared means of communication among individuals. Yes, a programming language is a formal way of instructing a computer how to behave, but a programming language may also be viewed as a way to define and communicate specifications to a high level of detail (the code is the ultimate spec, is it not?).
So as far as we may want to concern ourselves with the degree of subjectivity in software languages, tools, and best practices, I would say that the lack of subjectivity may indicate how well communication is facilitated.
Yes, individuals have certain proclivities that are expressed in their habits and tendencies, but that should not ultimately matter too much in the perfect platform for development.
Turning to my Maths PhD wife I asked if there's any subjectivity in mathematics. Her answer is yes there is, mainly in the way we as humans achieve the answer.
If a mathematical proof is the result, how you get to that result can vary. If the dataset is large you may need to use a computer, which can introduce errors, and thus debated about whether that is the right approach. Or sometimes mathematicians can disagree on the theory - one is trying to prove that x is true while the other is trying to prove that x is false.
I think the same thing exists in computer science. A correct answer is a program that runs correctly, but that definition of correct may be different for each project. Sometimes correct means no bugs. Sometimes it means running efficiently.
From here programmers can argue how best to achieve the "correct" result. A good example of this is is the FizzBuzz application. A simple answer would be just a for loop, but Enterprise FizzBuzz is also "correct" in that it produces the correct answer, but is generally laughed at as "bad" engineering due to its overcomplication of the idea (it was a joke app after all).
How large a role does subjectiveness play in programming? I'd say it's a very large part of what we do, simply because we are human, and because there are multiple ways of getting the "correct" answer so there is disagreement over which way is the best.
Studies have been done showing that certain practices reduce defect rates in software. For instance, a study found a strong correlation between cyclomatic complexity and the probability of being fault-prone. Other studies show the average effectiveness of design and code inspections are 55 and 60 percent. So it appears to be in our best interests to favor simplicity, check metrics, and do code reviews.
We're talking probabilities here, though. If I review your code, I'm not guaranteed to find 60% of your bugs. There are also few absolutes in software development; experienced developers know that the correct answer is generally "it depends." That said, there are a number of practices with objective data in their favor.
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I would like to work on a programming project in my spare time and would like to know
if there is a project where I can help the science community in some way?
Sure, plenty! I see I'm not the first to think of numerical computation libraries like Numpy/Scipy - the code in that is actually fairly mature but they could certainly use help documenting. There's also GNU Octave, which does much of the same things as Numpy but doesn't require Python. A slightly related area in which there's a lot of work to do is computer algebra systems (CAS), basically open source equivalents of Mathematica; for example Maxima, and more are listed at http://sage.math.washington.edu/home/wdj/sigsam/opensource_math.html. You could also help with visualization libraries, i.e. creation of 2D and 3D plots and figures. For Scipy the most commonly used plot generator is Matplotlib, for example. There are also loads of more specialized data visualization tools that I'm sure you can find with a few searches.
One area that I personally think needs a lot of work is creating GUIs for the programs mentioned in the previous paragraph; one major advantage that commercial programs like Matlab and Mathematica enjoy over their open source equivalents is easy-to-use graphical interfaces. Having a nice usable interface would be great for scientists who may not be skilled in command-line-fu, but open source projects have a long way to go if they're going to catch up.
Projects like scipy and numpy are largely contributed by the scientific community. I'm sure they would appreciate any help you thought you could provide.
I know BOINC is always looking for help
Edit: Here is their programming help page http://boinc.berkeley.edu/trac/wiki/DevProjects
The Bio* projects like BioPerl, BioPython, or BioRuby would certainly like some help, too.
http://sourceforge.net/search/?type_of_search=soft&words=science
In addition to searching open source projects online, you can try to contact your local university and ask if any of their researchers (students or faculty) need development help.
If you are still looking, feel free to contact me via my profile page - I know of a hardware product that needs software - it is used for research (chemistry and biology)
The nuclear ad particle physics communities make heavy use of ROOT, which is developed using an open source methodology. They accept suggestions and patches without much trouble. The main work is in C++, but there are binding and support for other languages as well.
I'm sure that other disciplines have their own domain specific tools. For instance, I know that there are open Computational Fluid Dynamics and Finite Element systems.
Have a look around. While domain knowledge would be helpful, most big tools are going to need help with routine stuff like RDBMS access, GUIs, documentation, and so on...
You can discover the current problems of Science by reading the abstracts of the academic journals. e.g. the Bioinformatics journal.
A few examples:
Find a faster/efficient methods to assemble a huge set of short DNA reads:
Find a way to build an efficient social scientific network
Find a way to compare thousand of human genomes
....
you could also propose your help on Nature Network:Collaboration or FriendFeed: The life scientists
There are many exicting opportunities in chemistry. There is a strong Open Source community, much of which is organized under the Blue Obelisk (http://www.blueobelisk.org). There have been major contributions in visualisation and algorithms which did not need previous chemical knowledge and the community is very welcoming to anyone who wishes to help.
For an example of the standard which has been achieved take a look at Jmol which visualizes molecules and other chemistry in 3D (http://www.jmol.org);
There is also real opportunity to do porting between platforms/languages. The commonest ones are Java, Python, C++ and we have been working in C#. You don't have to be an ace programmer either - contributions to data standards, data resources, tutorials, packaging, installers, testing, etc. are all highly valued.
Some of these projects are within the top 100-500 projects on Sourceforge.
Don't forget that if you find a project to be a bit over your head or you aren't able to really contribute, but you still like the idea of it, you can always donate!
Do you think that writing about software (i.e. having a blog) and speaking on software (and concepts) make you a better programmer?
Statistically speaking yes. You only retain about 20% of what you read and hear, but 80% of what you teach.
By writing about something or teaching about it, you force yourself to understand the concepts on a much deeper level.
UPDATE:
I wanted to update this with some links to more concrete data to support the statistics that I have been taught numerous times about learning retention rates. However, it would appear there is some controversy surrounding these numbers, even though the NTL Institute for Applied Behavioral Science maintains that research was done to back them up.
I believe that is the case. As with teaching, you develop a firmer grasp on the subject when you have to explain to someone else. You get to see what you understand and don't understand in greater detail.
Yes. In the work force, being able to communicate effectively is as, and sometimes more important than knowing every obscure detail about language X.
Absolutely yes. You have the chance to be challenged and questioned and second-guessed in ways you'd never think of on your own. It also gives you a chance to work on the organization and presentation of your ideas. All of this will feed back into the decisions that you make when you're writing code.
I would argue the opposite: that in general the good programmers love to write and speak about software. It shows that they are passionate about it, and won't accept crap.
Absolutely. Knowledge without regular using is useless. Talking about technologies, languages, methods, development processes, books etc. greatly improves overall experience and points possible ways of professional evolution.
Absolutely, for one simple reason: It challenges your preconditions. You could write an article about how perfect .NET is for a given situation, only to find someone has used it, and it turned out badly.
I think the main thing these activities do is force one to more thoroughly research things and research new things. Does this make you a better programmer? I think so.
I think it encourages you to be a better programmer generally by visualizing your opinions and by reading users responses. I don't think the fact that you have a blog or can display the ability that you are knowledgable about developing makes you better inherently but it might help motivate you to be better so you can keep up with your posts.
If you tend to write or speak about software then that means you're thinking about it and you have opinions. Caring about it enough to write makes you a better programmer.
I think that being able to speak and write well make you a better developer. Not necessarily because it will improve your programming skills, but because software development is a lot more than just banging out code. Whether it's for a company or an open source project, all but the smallest pieces of software are team products. In this environment, it's going to be the developer who can best communicate that will make the biggest contribution, not the one who is necessarily the best coder.
Teaching about software absolutely makes you a better programmer. Writing on a blog is not so far off.
Most of the things that I learned about .NET, I learned when I was reviewing it to be able to train newbie devs. So yes, speaking on software helps a whole lot.
Yes. If you get feedback (eg, blog comments), then doubly so. Others will invariably think of something that you didn't, but may never have had the chance to tell you if you didn't speak up first.
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What languages and tools do you consider a youngster starting out in programming should use in the modern era?
Lots of us started with proprietary Basics and they didn't do all of us long term harm :) but given the experiences you have had since then and your knowledge of the domain now are there better options?
There are related queries to this one such as "Best ways to teach a beginner to program?" and "One piece of advice" about starting adults programming both of which I submitted answers to but children might require a different tool.
Disclosure: it's bloody hard choosing a 'correct' answer to a question like this so who ever has the best score in a few days will get the 'best answer' mark from me based on the communities choice.
I would suggest LEGO Mindstorm, it provides an intuitive drag and drop interface for programming and because it comes with hardware it provides something tangible for a child to grasp. Also, because it is "LEGO" they might think of it as more of a game then a programming exercise.
My day job is in a school, and over the past few years I've seen or taught (or attempted to teach) various children, in various numbers, programming lessons.
Children are all different - some are quick learners, some aren't. In particular, some have better literacy skills than others, and that definitely makes a difference to the speed at which they'll pick up programming. I bet that most of us here, as professional computer programmers and the kind of people who read and post to forums for fun, learnt to read at a pretty young age. For those kinds of children, and if it's your own child who you can teach one-on-one, you could do worse than JavaScript - it has the advantage that you can do real stuff with it right away, and the edit-test cycle is simply hitting "refresh" in the browser. It gets confusing when you start to run in to how JavaScript does everything asynchronously, and is tricky to debug, but for a bright child under close tuition these problems can be overcome.
LEGO Mindstorms is definitely up there at the top of the list. Most schools now super-glue the bricks together to create pre-made models that can't have bits nicked off of them, but this shouldn't be a problem at home. Over on the Times Educational Supplement site (website forum for the UK's weekly teaching newspaper), the "what programming language is best for children?" topic comes up pretty regularly. Lots of recommendations over there for Scratch as an alternative to Mindstorms - bit more freedom than Mindstorms, again probably better for the brighter student who could also be given a soldering iron.
I've found that slower pupils can still have problems with Mindstorms, even though the programming environment is "graphical" - there's still a lot going on on screen, and there's a fair bit to remember (this was an older version, mind - haven't tried the snazzy new one yet). In my experience, the best all-round introduction to programming is probably still LOGO - actually a considerably more powerful language than most people give it credit for. The original Mindstorms book by Seymour Papert (nothing to do with LEGO - they nicked the title of the book for their product), one of the originators of LOGO, is the canonical reference for teaching programming to children as a "thinking skill" and for the concept of Constructionism in learning.
We've had classes of 7 or 8 year-olds programming LOGO. Note that we aren't aiming to make them "software developers", that's a career path they can decide on at some point post-16. At a young age we're trying to get them to think of "computer programming" as just another tool - how to set out a problem to be solved by a computer, in the same way they might use a mind map to help them organise and remember stuff for an exam. No poor child should be sat down and drilled in the minutia and use of a particular language, they should be left to explore and figure stuff out as they like.
I'll second Geoff's suggestions of Phrogram (used to be KPL), and Alice.
My only other suggestion is Lego Mindstorms NXT. The NXT's programming language is drag-and-drop, is very easy to use, and can do some very complicated tasks once you learn it. Also young boys usually like seeing things move. :)
I've used Alice and NXTs with some young kids, and they've taken to it very well.
Two possibilities are:
Scratch - developed at MIT - http://scratch.mit.edu/
and
EToys from the One Laptop per Child fame - http://wiki.laptop.org/go/Squeak
Full disclosure: I'm one of the guys who invented Kid's Programming Language, which is now http://www.Phrogram.com, which others have recommended here. Let me add some programmer-oriented info about it.
It's a code IDE, rather than drag-and-drop, or designer-based. This was intentional on our part - we wanted to make it easy and fun to do real text-based programming, particularly programming games and graphics. This is a fundamental difference between us and Alice and Scratch. Which you pick is a matter of the kid, their age and aptitudes, your goals. Using them serially with the same beginner might be a great way to go - if you do that, I would recommend Scratch, Alice, Phrogram as the order. Phrogram has worked best for 12 years and up, but I know dads with 6 year olds who have taught their kids with it, and I know 10 year olds who have taught themselves with it.
The language is as much like English as we could make it, and is as minimal as we could make it. The secret sauce is in the class-based object heirarchy, which is again as simple, intuitive and English-like as we could make it. The object heirarchy is optimized for games and graphics. 3D models are available, and 2D sprites. Absolute movement using screen coordinates is supported, or relative movement ala LOGO turtles - Forward(x), TurnLeft(y).
The IDE comes with over 100 examples, some language examples (loops), some learning examples (arrays), some fully-functional games and sims (Pong, Missile Command, Game of Life).
To give you a sense of how highly leveraged we made the language and the IDE: with 27 instructions you can fly a 3D spaceship model around a 3D skybox, using your keyboard. The same with a 2D sprite is 12 to 15 instructions.
We are working on a Blade-compatible release of Phrogram that will allow programs to run on the XBox 360. Yeah, the XBox, on your big TV. Nice motivator for getting a kid started? :)
Phrogram includes support for class-based programming, with methods and properties - but that's only encapsulation, not inheritance or polymorphism.
A tutorial and user guide is available,
My own ebook is available at Amazon and other places online, "Learn to Program with Phrogram!," and gets a beginner started by programming the classic Pong.
Phrogram Programming for the Absolute Beginner, by Jerry Lee Ford, Jr., is also available, as a paperback, at Amazon and elsewhere.
For a child, I would go with Alice. Any kid is going to like the drag-and-drop interaction that Alice uses better than trying to remember how to spell and punctuate any programming language. He/She will learn the basic programming structures (conditionals, loops, etc.) and will experience the fun of building an animated program they can show off to other family or friends.
A beginner CS class at the local community college actually uses Alice to teach programming in a language-independent way. It provides a good foundation for moving into programming in a particular language (or a few languages) down the road.
I recently saw a presentation about GreenFoot (a java based learning environment for children). It looked awesome. If I would have kids, I would give it a try
Link to the presentation
It is a very playful environment, where you could start with very basic methods. The kids learn thinking in an object oriented way (you cannot instantiate an animal, but you can instantiate a cat). And the better they get, the more of Java you can uncover for/with them.
I'd go with Scratch, some points regarding it.
It's a graphical programming language. It isn't text based (this might be
positive or negative). It does make it more intuitive and easy for kids (7 and
up).
It's actually highly object. The objects you write these graphical scripts have the code attached to them and can be reused and moved around.
Very Important: quick and impressive results. Kids need to get going fast and get results in order to get hooked.
I'd like to note that although many of us started programing at a young age in basic or logo and because programmer later in life doesn't mean those are good languages to start with. I think that kids today have much better options, like scratch or Alice.
Text based languages (python, ruby, basic, c# or even c) are dependent on external libraries and tools (editors, compilers) while something like Alice or scratch is all inclusive and will teach kids (not aimed at teens) programming concepts. Later they can move on and expand their learning.
Check out Phrogram (formerly KPL) and Alice
I'd say: give the kid a real C64, because that's how I got started. But, today... I'd say Ruby, but Ruby is a bit too chaotic. BASIC would be better in the long run. Processing is easy to learn, and it's basically Java.
The reason I recommend a C64 is because it's BASIC, but you still have to learn certain computer-related things, like the memory model, pixels, characters, character maps, newlines, etc. etc, if you want to do more advanced stuff. Also, if your kid finds it boring, you know his heart really isn't into coding.
I would pitch LOGO. It was something that was taught in my elementary school. It gives nearly immediate feedback, and will teach really basic programming concepts. Moving that little turtle around can be a lot of fun.
For a child, I would go with Alice.
Here is another vote for Alice. My 4 kids have had a ton of fun working with it and learning the basic concepts of programming. Of course to them it's all about socializing with fairies and ogres, but heck the darn legacy system I work on could use some faries and ogres too.
I'd recommend python, because it's so terse and expressive. Seems less likely to frustrate when getting started, but offers plenty of room to learn more advanced concepts as well.
Game Maker might be another approach. You can start simple with easy drag and drop development, and then introduce more advanced programming as you go. The book The Game Maker's Apprentice: Game Development for Beginners has a number of sample games and takes you through the steps required to make them.
I think python is a good alternative; it is a very powerful language also you can easily do a lot of things (not boring at all).
Checkout Squeak developed by Alan Kay who think programming should be taught at early ages.
How old? Lots of us stared with BASIC at some point, but before then, I learned the concepts of stringing commands together, variables, and looping with LOGO. Figuring out how to draw a circle with a triangle that can only go in a straight line and turn was my very first programming accomplishment.
Edit: This question & its answers make me feel old.
Though _why hasn't given it much love in the past year or so, for a while I was really excited about Hackety Hack. I think the key for most new programmers, especially children who are more than apt to losing interest in things, is instantaneous feedback. That was the really wonderful thing about Hackety Hack: a few lines of code, and suddenly you have something in front of you that does something. There are a few similar applications aimed at things like drawing graphics (one of which, I briefly assisted Nathan Weizenbaum on, Scribble!). Kids simply need positive feedback that they're doing something correct on a regular basis, else there's nothing to keep them interested in the task at hand. What I think the future is for teaching children to program is some sort of DSL built on top of a language with friendly syntax (these would include, arguably, Ruby, Python, and Scheme) whose purpose is to provide an intuitive environment for constructing simple games (say, Tic-Tac Toe, or Hangman).
I think you should start them off in C. The sooner they can get the hang of pointers the better.
See Understanding Pointers and Should I learn C.
I think the first question is: what sort of program would it be interesting to create? One of the things that got me started with programming as a kid (in BBC basic and then QBasic) was the ease of writing graphical programs. I could write a couple of lines of code and see my program draw a line on the screen straight away.
The closest I've seen to that sort of simplicity recently are the pygame library for python and Processing, a set of java libraries with an IDE.
I imagine that hacking on web pages would be another good way to get started: that would entail HTML, Javascript (using a library like jQuery), perhaps PHP or something along those lines.
Whatever tools you provide, the crucial thing is for it to be easy to get started straight away. If you have to write twenty lines of correct code and figure out how to invoke the compiler before you see any tangible results, progress is going to be slow.
There are many good suggestions here already. I really agree with Kronikarz. Get a retro computer (or emulator) that you are interested in and teach with that. Why a retro computer? Basic is built in. Making sounds and primitive graphics is a trivial task. The real deal might be better than an emulator because it will be a bit more fascinating to a child who is used to seeing only modern devices.
As I said here, I'd go for Squeakland and the famous Drive a Car example (powered by Squeak).
Smalltalk syntax is simple, which is great for children.
And later as the child evolves, he can learn more complex and even very advanced concepts that are also in Squeak (eg. programing statefull webapps with automated refactoring and automated unit tests!).
And like #cpuguru and #Rotem said, Scratch (also Squeak based) is great too.
I think Java might be a good choice simply because you can make GUIs easily, and see "cool things" happening. For the same reason, maybe any of the .NET languages. I've also heard good things about scripting languages (Ruby and Python, especially) for getting kids to learn how to program.
Well, if they're young and haven't learnt their ABC's you could try them on BF - non of those pesky letters and numbers to deal with.
I'll get me' coat.
Skizz
I would go with what I wish I had known first: a simple MS-DOS box and the integrated assembler (debug). It is great to really learn and understand the basics of talking to a computer.
If that does not scare away a child, then I would go the "next level up" and introduce C. This shouldn't be hard given that the basic concept of pointers, registers and instructions in general are well-understood by then.
However, I am not entirely sure, where to go next. Take the big jump to Lisp, Haskell or similarly abstracted languages or should there be some simple object oriented languages (maybe even C++) be thrown in or would that more hurt than help?
Looking at Alice, I see it is "designed for high school and college students". There appears to be another language/version called Story Telling Alice that is "designed for middle-school students"
Alice Download Page
I think Context Free Art might be a good choice, with output of graphics, it makes it a lot of fun learning about context-free grammar.
Try [Guido van Robot][1]. It's an excellent introduction to robotics, and it's a great way to introduce kids to the programming side of things (vs the "building the robots" side).
Wasn't Smalltalk designed for such a purpose? I think Ruby would be a good choice, as a descendant of Smalltalk.
I know in the first few years of high school we were 'taught' Logo, and strangely, HTML. After that, the progression went to macros in MS Office, followed by basic VBA, followed by Visual Basic.