grant

Coyotos and Genode OS

Coyotos and Genode are two operating systems about which I had never heard that were mentioned in an Ikarus Users mailing list thread that doesn’t seem to have been mirrored online.
Coyotos:

Coyotos is a secure, microkernel-based operating system that builds on the ideas and experiences of the EROS project.

Genode:

We understand the complexity of code and policy as the most fundamental security problem shared by modern general-purpose operating systems. Because of high functional demands and dynamic workloads, however, this complexity cannot be avoided. But it can be organized. Genode is a novel OS architecture that is able to master complexity by applying a strict organizational structure to all software components including device drivers, system services, and applications. The Genode OS framework is the effort to advance the Genode OS architecture as a community-driven open-source project.

Ikarus Adds Preliminary Debugger Support

In this post Aziz announced that Ikarus has preliminary debugger support. Awesome.

The Agenda of SICP

SICP (as it is often referred to) has its own agenda: convincing the reader that the most important thing computers can do is interpreting computer programs.

– Guido van Rossum

(via reddit)

How Spellcheckers Work

This looks like it might be a good article.
(via reddit)

Hand wiring an 8 bit computer

This looks like a real blast; designing, assembling, and running an 8 bit computer.
(via reddit)

One Man's Toy Projects

Here are one man’s toy projects. They look good and he has some good advice.

Chicago Code Camp 2009

Here is the link for Chicago Code Camp 2009. It looks fun.

VIM as Python IDE

Here is a nice article about using VIM as a Python IDE.
(via reddit)

XO Keyboard Field Repairs

Here is a funny yet practical post on XO keyboard field repairs.

Why Church chose lambda

Todd asked “Why [did Church choose] lambda and not some other Greek letter?”. Here are three answers:

1

Matthias:

The story is that in the 10s and 20s, mathematicians and logicians used ^ as a notation for set abstraction, as in ^i : i is prime. Church used ^` (i.e., a primed version of this symbol) for function abstraction, because functions are just sets with extra properties. The first type setter/secretary read it as λ and Church was fine with. True or not? I don’t know but it’s fun.

2

This paper (link provided by Dave Herman here):

(By the way, why did Church choose the notation “λ”? In [Church, 1964, §2] he stated clearly that it came from the notation “xˆ” used for class-abstraction by Whitehead and Russell, by first modifying “xˆ” to “ˆx” to distinguish function abstraction from class-abstraction, and then changing “ˆ” to “λ” for ease of printing. This origin was also reported in [Rosser, 1984, p.338]. On the other hand, in his later years Church told two enquirers that the choice was more accidental: a symbol was needed and “λ” just happened to be chosen.)

3

This paper (link provided by Dave Herman here):

We end this introduction by telling what seems to be the story how the letter ‘λ’ was chosen to denote function abstraction. In [100] Principia Mathematica the notation for the function f with f(x) = 2x + 1 is 2xˆ +1. Church originally intended to use the notation xˆ .2x+1. The typesetter could not position the hat on top of the x and placed it in front of it, resulting in ˆx.2x + 1. Then another typesetter changed it into λx.2x + 1.