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MIT App Inventor

appinventor.mit.edu

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I like the ideas behind the app inventor programming language. It has a lisp-ey look and feel to it. The language is made out of blocks that look like puzzle pieces. The shape of the piece stands for it's syntactic meaning, there's a distinct shape for expressions and statements. The color of the piece is it's type, e.g. red for boolean.

So an "if" statement is a statement piece that has places to plug in a boolean (red) expression piece and two statement pieces. That's structure and interpretation of programming languages for you.

The weakness of the language is the difficulty of representing recursion. I think there was another MIT project that did this well, their program representation was a visual graph where recursion was represented as back edges. This is similar to how the Haskell compiler stores programs internally as graphs. An interesting feature of the visual graph programming language was that all variable and function names are optional (but useful) comments.

I feel that researching and experimenting with non-text representations of computer programs is worth the effort.

An interesting feature of the visual graph programming language was that all variable and function names are optional (but useful) comments

Do you perhaps remember the name of the project? This is mightily interesting. I've thought about this many times, that if you represent a program as a graph (instead of a tree) you don't really need 'names' or 'symbols' as such (except to make it understandable to humans), just connections. This allows for a cleaner separation of syntax and semantics, and would make it easier to manipulate programs without having to type.

I wish I remembered it, but I have forgotten the name and can't find it with google. If you find it, please reply to this thread.

My seven-year-old son has recently been getting his first experience of programming using the Lego Mindstorms visual programming environment [1]. It uses a similar 'jigsaw puzzle' representation, and he just found it instantly intuitive. It has similar limitations to App Inventor, but I don't see support for recursion as being too important for this type of programming.

[1] Example: http://www.techno-stuff.com/AirPressure.htm

>> but I don't see support for recursion as being too important for this type of programming.

That is a fair point, recursion is not directly used very often in conventional programming. However, to me, recursion is the missing link that makes a language a programming language (Turing complete).

There is still work to do to find a better structured representation for computer programs than a string of characters is.

PS. I think your son is old enough and motivated enough to get an Arduino or a Python book and start learning ;) That's about the age I started programming after seeing my dad stare at a blue text-filled screen all night trying to make ends meet as a freelancer.

For the time being I'd like to keep the programming he does related to something physical - like the lego robot you program using the mindstorms environment. At his age I think he could become bored with just shuffling bits or putting text onto a screen, and anything sophisticated enough to impress him and hold his interest (probably graphical) might be to complex. Also the challenge of physically building a controllable robot is a nice contrast to the abstract programming task.

I'd like to try him with Scratch (http://scratch.mit.edu/) before moving on to text-based programming (if he wants to). Python is a good idea: we could learn it together...

I do have a netduino, and he's seem me working on that, but C# requires a lot of up-front knowledge. Arduino and wiring might be in his range.

He's a bright kid and I've learned a lot just by seeing how he conceptualizes these ideas.

He might be interested in the Mindstorm components in App Inventor

Thanks! I didn't know about that. Unfortunately we are using the older RCX mindstorms system, and the app inventor components only seem to work for the newer NXT system.

IIRC Hal Abelson used Kawa Scheme as a base to implement it.

Ahhh, "4th generation languages" come to mobile apps.

I'm _so_ glad all those "idea types" and "business cofounders" won't need my advice or services anymore, 'cause now they can make their own apps without needing any of us annoying technical types telling them "actually, you can't do that"…

(Who wants to port RAMIS to iOS?)

This looks like google app inventor reborn, yeah? Seems like a noble goal, but not implemented in a satisfying way. I'd like to see an example of something decent created with these tools.

I would definitely be more interested in this kind of thing if it ran on-device, as well. Like AIDE (which is awesome, btw).

Many of us are working on touch-based programming on tablets, I think there will be many interesting tablet-based programming environments coming on line this year.

One of the problems I have with AppInventor is that it feels like procedures (in a hidden event loop) are not the right abstraction for the high-level programming model that they are aiming for.

The top hit from google for AIDE is not the AIDE kennywinker is referring to. https://play.google.com/store/apps/details?id=com.aide.ui... is the Android Java IDE, which is the AIDE referred to.

Thank you, I didn't take the time to check my googles before omitting a link. :)

Is this based on Scratch? http://scratch.mit.edu/

http://en.wikipedia.org/wiki/Google_App_Inventor#History

Can anybody comment on its efficaciousness?

I made their sample app in about 10 minutes, its fun at least.

iPhone alternative: https://blueprint.io

I thought they were going to open source this, but it is still a hosted software as a service?

It is open source: http://code.google.com/p/app-inventor-releases/

Will they allow apps made with App Inventor to be published on the Play Store this time? Because I think when Google owned it they said they won't accept apps made with it on the market.

Because I think when Google owned it they said they won't accept apps made with it on the market.

That's not true at all. I'm not aware of anyone who actually did publish anything, but Google didn't stop you doing it.

Wrong. Apps made in Google App Inventor could not be published to the market.

Here's how you did it: http://appinventor.blogspot.com.au/2011/04/how-to-publish-ap...

Here's another example: http://www.crucialthought.com/2011/05/15/publishing-an-app-i...

I think the confusion was that the AppInventor FAQ said you couldn't do it - but only because they didn't provide an out-of-the-box way to do it. That's quite different from banning it (which is what the OP implied).

Edit: and here is a thread about doing it with the MIT hosted version: https://groups.google.com/forum/embed/?fragments=true#!topic...

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