Author: grant

NexJ Scheme

NexJ Scheme is an open source project providing an efficient and powerful interpreter for the programming language Scheme that executes in a Java virtual machine.

Today I was sort of shocked to learn that there is another implementation besides SISC and Kawa that runs on Java!
There wasn’t even an announcement for NexJ on comp.lang.scheme and NexJ has been around for two years :(! Rather it was mentioned on scheme-reports this week.

Tarsnap: Online backups for the truly paranoid

Tarsnap is a secure online backup service for BSD, Linux, OS X, Solaris, Cygwin, and can probably be compiled on many other UNIX-like operating systems. The Tarsnap client code provides a flexible and powerful command-line interface which can be used directly or via shell scripts.

The design of Tarsnap was guided by the following four principles:
Security: Backups should be secure against attackers ranging from “script kiddies” up to major world governments, even if they can compromise the systems on which the backups are being stored. Backups are supposed to be a tool for mitigating damage — not a potential vulnerability to worry about!
Flexibility: Backups should be flexible and convenient. When you decide you want to create an archive, you should be able to store in it whatever files you want; if you decide that you want to delete an archive, you should be able to do it whenever you want, without impacting other archives; and there should be no arbitrary limits on how many archives you have stored, how often you can create new archives, or how long you can keep them for.
Efficiency: Backups should be efficient, using a minimal amount of storage and bandwidth. If you archive the same file twice, it should still only be uploaded and stored once; likewise, if you move, rename, copy, or make small changes to a file (e.g., adding a small amount of new data to the end of a log file or mail spool) you should never need to re-upload the entire file.
Utility: Backups should be provided as a utility, with linear (i.e., per-GB) pricing. Forcing people to figure out ahead of time how much data they want to back up so that they can sign up for the right “plan” is dumb, and having some customers subsidize other customers is inherently unfair.

— tarsnap website
Looks like an interesting service.

How one class brought SICP back at MIT

Zombie-like, 6.001 rises from the dead to threaten students again. Unlike a zombie, though, it’s moving quite a bit faster than it did the first time. Like the original, don’t walk into the class expecting that it will teach you Scheme; instead, it attempts to teach thought patterns for computer science, and the structure and interpretation of computer programs. Three projects will be assigned and graded. Prereq: some programming experience; high confusion threshold.

(via MIT via keegan via planethaskell)

How to Take a Calculus Test

Show what you know.
Don’t invent new math.
Don’t contradict yourself.
Do the easy questions first.
If you don’t know how to do a problem, start by writing down relevant things that you know are true in general.
Break difficult problems into manageable pieces.
Know what a function is, and know what things are functions.
If you aren’t taking a derivative, it’s probably wrong. (see the explanation below)
If you’re doing obscene amounts of computation, it’s probably wrong.
Don’t care about the final answer.

(via Jeremy)

Version Control in Dolphin Smalltalk

If you’ve ever wondered how to do version control in a Smalltalk system then check out these videos that Andy Bower recorded for our benefit:
Sts Setup: http://bit.ly/StsSetup
Sts Projects: http://bit.ly/StsProjects
Sts Changes: http://bit.ly/StsPkgChanges
Sts Project Changes: http://bit.ly/StsProjChanges
Sts Community Repository: http://bit.ly/StsCommRepo
(lost the source)

Dolphin runs under Wine

Folks,
As promised I have put up a blog post on how to get Dolphin running native under Wine (in this particular case on Mac OSX using a free product called WineSkin). You can find the blog at:
http://object-arts.com/blog/blog.html
There are a few videos to go along with the blog and these can be found in the OA video library at:
http://object-arts.com/support/videos.html
Best regards
Andy Bower

(via comp.lang.smalltalk.dolphin)

Mounting a Sparseimage with Automator in OS X

I use Carbon Copy Cloner to backup the Mini to an encrypted sparse image. OS X 10.6 used to mount the image automatically but quit doing so and I can’t figure out why. In lieu of that I built an Automator script to mount the share so that CCC could mount the image. That worked until upgrading to 10.7.
My final solution was to add a final step to the script asking the user to mount the sparse image manually.
This site showed how to do so like this:

tell application "Finder" to display dialog "Empty Trash" with icon 2