PLT – A community of people working on ambitious projects

Anyone who has poked around in the Scheme or Functional Programming community has no doubt heard about PLT, or at least one of its projects, which include DrScheme and the book How To Design Programs. PLT is a group of people spread across four universities that works on a number of projects, some of which involve making really cool software, and others which involve teaching programming.

They’ve created a complete graphical programming environment called DrScheme, which includes a Scheme interpreter, various Scheme libraries, and an IDE written in Scheme using their libraries. It even has its own HTML renderer that is used to implement the Help Desk feature of DrScheme.

They’ve used PLT Scheme (the umbrella name for the different distributions of their Scheme implementation) to build:

  • A PLT web server, which presumably is used to host their own website, which is well designed.
  • A Slideshow application, which Matthew Flatt uses for in-class presentations
  • PLaneT, a package repository for PLT Scheme

Four of them wrote a great introductory programming book, How To Design Programs, (HtDP) which covers a lot of practical programming concepts that were sadly skipped over in my C. S. program.

Using HtDP, they have a TeachScheme! project, which aims to “turn Computing and Programming into an indispensable part of the liberal arts curriculum” [1]. This is an important goal. Even if most people in other fields don’t program as part of their job, I think it’s a good idea for them to learn enough to understand the process of programming, as it often effects their work. HtDP starts at a level that most high school student ought to be able to understand, while still being interesting to a graduate of a state university’s C. S. program. That is an impressive achievment.

I think that in order to make a really good learning organization, you’ve got to have ambitious projects and invite all members to participate. PLT certainly has more than its share of ambitious projects – a Scheme compiler, language extensions, a portable GUI framework, a web server and application framework, a package repository, and an HTML renderer. The same could be said about MIT, with their wide variety of operating systems, graphics, and compiler projects. It should be possible for any school to work on something along those lines. The first step would be for a member of faculty to start an ambitious project, and invite students to participate (hopefully with pay for anyone who does substantial research).

To start an ambitious project, you need something to work on. Fortunately, there are a lot of ideas already out there, and it’s not that hard to come up with an idea. In the words of John Locke:

The acts of the mind, wherein it exerts its power over simple ideas, are chiefly these three: 1. Combining several simple ideas into one compound one, and thus all complex ideas are made. 2. The second is bringing two ideas, whether simple or complex, together, and setting them by one another so as to take a view of them at once, without uniting them into one, by which it gets all its ideas of relations. 3. The third is separating them from all other ideas that accompany them in their real existence: this is called abstraction, and thus all its general ideas are made.

John Locke, An Essay Concerning Human Understanding (1690)

A lot of programming projects are started by a programmer noticing problems that take lots of repetetive work to solve, and coming up with useful abstractions. Ruby On Rails was started this way. There’s a very good chance that the next big thing will as well.


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