[Part 3 of the HP Calc series ] In this post, we’ll create a 96-line F# emulator for the HP-35 calculator with which we’ll run the 960 byte (!) ROM image. As you may well know, I am a calculator freak. The 40-year-old HP-35 is an especially...

[The twelfth in a series of posts on the evolution of TransForth ]   It’s been quite fun playing with this Universal Machine from the Cult of the Bound Variable . In this post we’re going to continue the journey toward building a full Forth for this...

I’ve been having some fun playing with the Kinect SDK and the Lego NXT kit . The protocol to talk to the Lego brick over Bluetooth is pretty straight forward. Below is a little F# module for most of the basic commands. I’ll fill out the full set soon...

[The eleventh in a series of posts on the evolution of TransForth ] If you think coding with punch cards is old school, you should try using sandstone tablets! Legend has it that members of the Cult of the Bound Variable designed and may have even...

[The tenth in a series of posts on the evolution of TransForth ] This post may not quite be deserving of a wizard’s cape and 2001 Space Odyssey background music as when Sussman writes out Lisp in Lisp (at 34:34 - my absolute favorite SICP lecture...

Continuing my concatenative language kick, I’ve been having fun playing with Retro ( http://www.retroforth.com ) and couldn’t resist making an F#-based VM on which to run it. It is an elegant, minimal Forth with an important twist. What caught...

Longest hailstone sequence with starting number under one-million. let hailstone n = Seq.unfold ( function 0L -> None | 1L -> Some(1L, 0L)                                     ...

Some may call it “pointless”, but I absolutely love the point-free tacit programming style . The level of brevity can be truly astounding! Some of the terseness comes from not having to mention parameter names all over the place and much of...

[The ninth in a series of posts on the evolution of TransForth ] The dictionary we have at the moment is split across two worlds. The definitions are in Forth-world; packed into plain memory. But we still have the F#-world mapping of WordRecord s to those...

[The eighth in a series of posts on the evolution of TransForth ] They say that the inner interpreter is the heart of Forth and outer interpreter is the soul. It’s time to give TransForth a heart transplant! To really understand what we’re...

[The seventh in a series of posts on the evolution of TransForth ] At this point we have a reasonably complete Forth that’s pretty fun to play with. Like I said in the first post though, we don’t just want to build a Forth in F#. Stopping...

[The sixth in a series of posts on the evolution of TransForth ] There’s beginning to be more Forth than F# in these posts! The last major piece we’re missing in the language, aside from some compile-time trickery we’ll get into later...

[The fifth in a series of posts on the evolution of TransForth ] Sadly (or happily), we’ve come to a point at which we need to begin thinking like an assembly programmer in order to appreciate the mechanics of Forth’s control flow...

[The fourth in a series of posts on the evolution of TransForth ] We’re getting very close to the point at which we’ll need to start moving closer to the machine with things like direct memory access. Implementing IF / ELSE / THEN ,...

[The third in a series of posts on the evolution of TransForth ] Now that we have Forth hobbling along, we can start to peel away the scaffolding. Some of the things we’ve defined in F# can now be redefined in Forth instead. As we go along, I...

[The second in a series of posts on the evolution of TransForth ] In the last post we completed the tokenizer/parser and the REPL along with some baked in primitives. We now want to be able to add to the dictionary of known words from within Forth...

[The first in a series of posts on the evolution of TransForth ] I’ve been enthralled by retro computing recently and have been filling my bookshelf [yes, actual bound paper books] with (nearly) extinct programming language topics: Lisp, Fortran...

Our team’s been doing Katas to get the hang of TDD. One such kata ( calculating bowling scores ) struck me as insanely simple with pattern matching in F#: let rec score acc = function | 10 :: (a :: b :: _ as t) -> score (acc + 10 + a + b)...

Brushing up on “whiteboard coding” for internal interviews… Inspired by Hal Ableson’s streams-based solution to this old classic in the SICP lectures, here’s a pretty concise n-Queens solution: let rec Solutions n...

[Part 2 of the HP Calc series ] Making the JavaScript-based HP-35 microcode emulator has been a fun little project. Last time we disassembled the original bits from the ROM. I say “disassemble” but really our microcode instructions were...

[Part 1 of the HP Calc series ] I recently started a super-geeky side hobby of collecting vintage calculators and got my hands on a pair of HP calcs. The more I learned about the internals of the devices, the more intrigued I was. Jacques Laporte...

[Part 1 of the FScheme series ] One of my New Year’s goals is to re-read Lisp in Small Pieces and implement all 11 interpreters and 2 compilers. As much as I like the "Lisp in Lisp" idea and enjoyed the eureka moment in SICP when Sussman writes...

First ten digits of sum of following one-hundred 50-digit numbers. It would be interesting to do without BigInts. Could use doubles with enough precision for just the first ten digits or some such thing, but just wanted the correct answer to plug into...

First triangle number to have over five hundred divisors. let naturals = Seq.unfold ( fun i -> Some(i, i + 1)) 1 // from prob7 let triangleNums = Seq.scan (+) 0 naturals let isFactor n d = n % d = 0 let factors n = seq { 1..int (sqrt (float n))...

Greatest product of four adjacent numbers (up, down, left, right, or diagonally) in this 20x20 grid: let grid = [|08;02;22;97;38;15;00;40;00;75;04;05;07;78;52;12;50;77;91;08; 49;49;99;40;17;81;18;57;60;87;17;40;98;43;69;48;04;56;62;00; 81;49;31;73;55;79;14;29;93;71;40;67;53;88;30;03;49;13;36;65;...