Nils M Holm's Bits and Pieces

Who am I? | No, really!

New Book: Introduction to Statistics

Learn to Program

Practical Compiler Construction: This book offers a tour through the full compiler for a clean and sane subset of the C programming language (C89), covering lexical analysis, parsing, semantics, code generation, optimization, and runtime support, including lots of clarifying annotations and diagrams. The SubC compiler discussed in the book is in the public domain and can be downloaded below.
The SubC Compiler: SubC is a clean, fast, and simple compiler for a subset of C89 that can compile itself on various BSDs, Linux, Windows, and other systems. It also cross-compiles to DOS. Its code is in the public domain.
Scheme 9 from Empty Space (Book, Interpreter, Play the Game): S9fES is both a book and an interpreter for the R4RS Scheme programming language. The entire S9fES code is in the public domain. The book offers a guided tour through every single line of the interpreter with lots of annotations and diagrams. It covers even the gory details, such as macro expansion, call/cc, and tail-call elimination.
Klong, a simple array language: Klong is an array language, like K or APL. Its programs use powerful operators to manipulate lists (vectors) and (multi-dimensional) arrays. Klong is a mathematical notation rather than a programming language. It uses the ASCII alphabet and has simpler semantics than K. Its interpreter is based on S9core and should run in any ANSI C environment.
mLite, a lightweight, dynamic functional language: mLite is a general-purpose, functional, lightweight, dynamic programming language. It borrows ideas from both the Scheme and Standard ML languages, taking most of its syntax from ML and its dynamic nature from Scheme. It extends ML-style pattern matching by adding guarded patterns and also introduces the principle of "implicit guards".
Sketchy Scheme, 4.5^th Edition (PDF): A beginner-friendly introduction to functional programming in Scheme. This is a step-by-step guide to problem-solving in the functional way. The book contains lots of example, from trivial to advanced, as well as Scheme definitions of many standard procedures, an informal explanation of continuations, and a digression dealing with lambda calculus. Got stuck with SICP? Try this one!
Logic Programming in Scheme (PDF): An introduction to the principles of logic programming in MicroKANREN, covering predicates, goals, negation, cutting, and the translation of functional code into declarative code. Chapter two uses logic programming to solve the well-known Zebra puzzle, and chapter three contains the complete and annotated implementation of MicroKANREN in portable Scheme.
See also: code from the book

Odds & Ends

More or less random things that keep me busy.

Love, Impending Doom, and the Drake Equation: Why we are doomed as a civilization, and why this is both inevitable and prefectly OK. An essay about a possible explanation of the Fermi Paradox.
What to do with a high IQ?: Most people think that a high IQ will make you sucessful, attractive, socially respected, etc, but many people actually suffer from being highly intelligent. This paper investigates the seeming paradox. Basic statistics required.
Where Do The Failed 0.1% Go? (PDF): An article about two highly intelligent people who fell through the social safety net. Including suggestions on how not to fail such people in the future. Published in Vidya #324/325 in 2015. Erratum: on the bottom of page 3, "window of 30 IQ points" should be "window of 15 IQ points".

The Attic

There are free PDF copies of some draft versions and obsolete books at
http://www.bcl.hamilton.ie/~nmh/t3x.org/zzz/ .

Books

Lightweight Compiler Techniques (PDF): A discussion of techniques for implementing simple yet efficient compilers for procedural languages. Covers all phases of compilation: scanning, parsing, optimization, code synthesis. Little theory, lots of code. The T3X compiler described in this book can be found below.
Zen-Style Programming (PDF): An introduction to various aspects of computer science at break-neck speed: functional programming, arbitrary-precision arithmetics, meta-circular evaluation, searching and sorting, the limits of computability, streams and generators, formal grammars, syntax analysis, regular expressions, logic programming, design and implementation of programming languages, and much more...
Code: Zen Lisp
Die Anatomie einer Programmiersprache (PDF): An early precursor to Lightweight Compiler Techniques in German.
Code: BSL Compiler Kit

The Rest

BTN11: BTN11 is a two-pass assembler that generates absolute binaries for various models of the PDP-11. It is written in K&R C.
FOOGOL IV, V5: Lindberg's FOOGOL IV compiler hacked up to emit 386 assembly language. Also converted to modern (ANSI 89) C. Compiles fine with SubC.
MINBASIC: An interpreter and compiler for an obscure BASIC dialect that I have created back in the early 1990's. Includes some simple games as example programs. The compiler is written in MINBASIC.
Mini Scheme v.3: An extended but still tiny version of Moriwaki and Kida's Mini Scheme interpreter, featuring string operations, type checking, file operations, improved macro syntax, and more complete error checking.
PD Korn Shell: A slightly patched version of pdksh, compiles on most modern BSD's and has a clear-screen function that you can bind to a key. This was the one tcsh feature I was missing most in pdksh. And: yes, I actually use this shell. :-)
S9fES Interpreter, 2007 version: The original version of the Scheme 9 interpreter from the first edition of the book, including fixes to the errata from 2009.
SOL Operating System: SOL is a tiny, FORTH-based operating systems for the PDP-11 (sol-11.zip) and the IBM PC (sol-86.zip). There is also a generic version (sol3.zip) running on a virtual stack machine. You need BTN11 (above) to compile the PDP-11 version. Bootstrapping the other versions requires a working T3X compiler. Good luck!
T3X Compiler, version 8.1.7b: T3X is a lightweight procedural language with backends for the 8086 (EXE), 386, Alpha, and the Tcode Machine. It features modules, objects, a full optimizing compiler, and a set of tools for manipulating Tcode. The Tcode port of the 8.1.7b compiler works fine on 64-bit systems. Development of T3X ceased in 2004. Version 6.8 of the compiler is described in the book "Lightweight Compiler Techniques" (above).
USELESS: An interpreter, compiler, and editor for a super-terse dialect of FORTH. Brevity = expressiveness? You decide. Lots of funny sample programs included.

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