I wrote Interpinkie, a basic Finger client in Interlisp that runs on the Medley environment. This is the main window of the program:

It was a fun challenge considering I couldn't use Medley's TCP/IP stack.

I always wanted to do some network programming with Medley. But the bitrot of its TCP/IP stack left it in a non working state since before the Medley Interlisp project, and the revival effort hasn't got around to the stack yet. The XNS stack still mostly works with the Dodo Services XNS implementation. But, as far as I know, XNS provides LAN services and I'm not sure whether or how it allows access to the outside Internet.

So I cheated and reached for Medley's escape hatch.

As part of the Medley modernization effort, the UNIXUTILS library module provides the ShellCommand function to run a Unix program on the host operating system and send the output to a stream. Since I can run arbitrary Unix commands from Medley, it's trivial to build a client that talks the Finger protocol via Netcat.

For example, to run the Finger query amoroso@happynetbox.com I can just execute this from the Linux shell:

$ echo "amoroso" | nc -C -w 3 happynetbox.com finger

where -C sends \r\n as line-ending, -w 3 sets a timeout of 3 seconds, and finger is the Finger port number as per /etc/services.

All Interpinkie does is to build and feed a query to ShellCommand, pipe the output through tr to remove extra \rs, and redirect the output to a suitable destination.

The Interlisp function QUERY.FINGER.SERVER wraps this functionality. By default the output goes to the primary output (Interlisp jargon for stdout), or optionally to a separate window with menu options for running another Finger query or quitting the program.

Interpinkie builds upon user interface techniques I used in previous projects such as attaching a menu to a TEdit window.

TEdit, the WYSIWYG the rich text editor of Medley, can be driven by other programs that send output to the editor buffer. This is handy as the programs get an automatically repainted scrollable window for free from TEdit. In addition, Interpinkie attaches a command menu to the TEdit window and uses TEdit's prompt window (Interlisp jargon for an edit field and status area) to request input and display errors.

Unlike my previous Interlisp projects, however, Interpinkie doesn't call the TEdit API to insert text in the buffer. Instead, the program redirects the ShellCommand output to the Lisp stream associated with the TEdit window, causing the text to appear in the buffer.

By default ordinary Lisp printing functions such as PRIN1 and PRINT send the output to the REPL or optionally to another Lisp I/O stream. Along with these output destinations, some Interlisp components and programs like TEdit have an associated stream. So it's easy to send output to TEdit by just printing to the stream returned by (TEXTSTREAM Window), where Window is a TEdit window, or redirecting to that stream the output of printing functions like PRIN1. In other words, ordinary stream I/O is the API.

Since ShellCommand accepts a stream as an optional argument, QUERY.FINGER.SERVER passes TEdit's stream to ShellCommand thus causing the output to go to the editor buffer. The benefit is Interpinkie uses the same QUERY.FINGER.SERVER function to output to both the primary output and a TEdit window.

If the destination is a window Interpinkie does some additional processing before and after sending the output. For example, before doing output the program updates the window title to reflect the Finger query, and sets the TEdit buffer to read-only once the output finishes.

These days there are not many Finger servers and I was lucky to stumble upon happynetbox.com. It is managed by Happy Net Box, a nice public Finger server anyone can sign up to for for free and publish a status file. Happy Nex Box was essential for developing and testing Interpinkie, as well as fun — and addictive — as you can see by running the query random@happynetbox.com to look up a random user.

#Interpinkie #Interlisp #Lisp

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For Chrismtas 2024 I bought myself a lovely little Cardputer uLisp Machine, an M5Stack Cardputer that can run uLisp.

The M5Stack Cardputer is a card-sized, microcontroller-based portable system for home automation, hobby, and industrial applications. Although not designed for Lisp the Cardputer can run uLisp, an implementation optimized for microcontrollers. This is my unit:

The uLisp system provides a capable Lisp implementation, a rich anvironment, debugging and editing tools, and lots of libraries and examples. It's well maintained and has an active user community.

Motivation

Like many Lispers I always wanted to play with Lisp on the bare metal and the Cardputer uLisp Machine is a simple and inexpensive solution.

uLisp runs on a wide variety of microcontrollers and boards. I picked the ESP32-S3 based Cardputer because it's compact, can run off rechargeable batteries or USB without an external power source, and comes with a graphics display. And at $29.90 it was a no brainer.

Hardware

The Cardputer is a self-contained device with a keyboard, a 240x135 color TFT display, a USB-C port, and a microSD card slot.

Despite the minuscle keyboard, if I hold the Cardputer with both hands I can accurately press any key with my thumbs. However, the keys are very sensitive to pressure and if I hit one with slightly more force than needed I end up repeatedly typing the same character. Entering code and expressions with the built-in keyboard isn't practical for anything longer than a line or two.

The stamp sized display is tiny too but my new eyes help me read the microscopic text on it.

Software

The first thing I did was to install the uLisp firmware to replace the stock system software. The installation procedure is straightforward, took a few minutes, and required only the Arduino IDE which I run on Linux.

There are two main ways of interacting with uLisp. The first is to access the REPL using the Cardputer keyboard and display, the other is to connect from a desktop computer over a USB serial line via the Arduino Serial Monitor or a terminal emulator such as GNU Screen or Minicom. There is also experimental user contributed code for accessing uLisp from Emacs via an inferior Lisp mode or Swank.

A limitation of interacting over USB is that sending code blocks longer than 256 characters overflows the serial buffer, which results in a string of error messages due to the dropped characters.

A workaround is to preceed the code with a comment line starting with a semicolon ; which temporarily turns off echo mode on the device and prevents it from being overwhelmed. Lisp mode on Emacs has no support for the workaround though. So the extra comment line needs to be manually copied from the source buffer and pasted into the inferior REPL along with the code, instead of executing commands such as eval-defun or C-M-x. This introduces friction in the rapid cycles of REPL and editor interactions Lispers are used to.

A showstopper

The limitations of interacting with the Cardputer over serial are just inconveniences that may be fixed by improving existing tools. But a showstopper forces me to set the Cardputer aside until a major Arduino core issue is resolved.

The Cardputer's ESP32-S3 native USB manages the serial port via software and currently has a nasty bug: if the receive buffer fills up too fast the ESP32-S3 will crash and disconnect. I can't do anything practical with the Cardputer without reliably sending medium or large Lisp code blocks to uLisp for evaluation.

The uLisp website does warn about the issue but I incorrectly assumed it affected the Cardputer only when connected to Macs, whereas I use Linux.

Only the Arduino team can fix this issue not caused by uLisp. But since it has been known for a couple of years I’m not holding my breath.

#Lisp

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The end of the work on WebCard marked the completion of my RetroChallenge 2024 project, in time as hoped.

I accomplished the initial goal of extending NoteCards to visit websites. This is my Linux desktop after traversing a NoteCards link to a Web card which opened the associated URL in Firefox:

As the RetroChallenge encourages to do I learned a lot, shared my experience, and had lots of fun with retro stuff.

WebCard is not my first NoteCards project but helped me explore other features of the system, particularly the definition of new types of cards. Most of the work on WebCard involved researching the NoteCards API and writing code.

Once I understood the relevant API calls, implementing the planned features took relatively little code. NoteCards comes with an extensive, well designed and documented API that enables to add a lot of functionality by mostly plugging into the public hooks.

The NoteCards manual has nearly all the information I needed. However, to understand some features or subtle points of the API I had to study some of the NoteCards code, particularly the source that defines the File card type because of the similarities with what WebCard does. Some throwaway code and experimentation with the interactive Lisp environment plugged the last information gaps.

The project generated a flow of material for my blog and Mastodon profile. I posted frequent short updates on Mastodon and longer reports on the blog. This drained time and focus too.

The main takeaway of the project is that Medley Interlisp is a rich toolbox with which new programs can be developed by combining other programs as building blocks. NoteCards itself builds upon the TEdit text editor, the Sketch line drawaing program, the File Browser, and other tools.

As my first RetroChallenge I was lucky to complete the project. I set a goal reasonably achievable in one month but the actual work faced some unexpected detours that didn't impact the deadline.

What else to say? Mission accomplished.

#WebCard #Interlisp #Lisp

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To complete WebCard for my RetroChallenge 2024 project I created a demo notefile, a file that stores the data of a NoteCards hypertext.

The notefile WCDEMO.NOTEFILE contains exmples of Web cards filed into various types of containers and cards such as fileboxes and Text cards. It provides some ready made Web cards for exploring WebCard.

This screenshot shows the main cards of the demo notefile:

The link icons with the globe bitmap at the left of the outlined text are links to Web cards. Clicking such a link in NoteCards opens the associated URL in a web browser, which is the main feature of WebCard.

#WebCard #Interlisp #Lisp

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With the last feature of WebCard behind me I proceeded with the next task to wrap up my RetroChallenge 2024 project: documenting the system.

Since WebCard enhances NoteCards with only a few simple but significant features a full manual would be overkill. So I added to the README file of the project repo some new sections on the requirements and dependencies, the installation, and the usage of WebCard.

The documentation assumes familiarity with NoteCards and Medley Interlisp, large systems in themselves, and describes only what WebCard adds to NoteCards. It explains how to create and manage Web cards and traverse links to them.

In addition the README file now has a screenshot that shows a website opened by WebCard in NoteCards.

#WebCard #Interlisp #Lisp

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NoteCards link icons leading to cards of a certain type can and typically do have a custom bitmap associated with the type.

WebCard cards of type Web initially inherited the bitmap of the parent type Text, a stylized NoteCards blank card frame. To visually differentiate links to Web cards I added a new bitmap, here open in the bitmap editor of Medley Interlisp:

The bitmap at its actual size of 21x18 pixels is near the top left corner of the window. It represents a blank card frame with at the center a globe crossed by meridians and parallels, a common symbol of web links.

Aside from some misunderstandings on defining Interlisp bitmaps, adding a bitmap to WebCard was easy.

Once designed and defined the bitmap itself I passed it as the value of the LinkIconAttachedBitMap property along wiht the other arguments of NCP.CreateCardType, the NoteCards API function that defines new card types.

The hard part was coming up with a suitable bitmap, which kept me busy on and off for a couple of weeks.

As an artistically clueless geek my original plan was to pick a public domain icon, scale it to the required size, and import it in Medley Interlisp. Although this Lisp environment predates most modern image file formats, Andrew Sengul wrote a Lisp tool that can convert from PBM to the native Interlisp bitmap format.

I soon found a nice globe icon. Then I was unwillingly thrown into a rabbit hole of NetPBM, Gimp, and ImageMagick tools and options, struggling to produce the right format Andrew's tool could process.

I learned the hard way that if an image contains only black and white pixels, and no other colors, it's unnecessarily difficult to obtain a black and white, 1-bit depth file. Most tools save to 8-bit grayscale despite claiming to do 1-bit black and white.

When I finally imported the rescaled, converted PNG into Medley I realized it was an unlegible tiny blob.

Link icon bitmaps have a size of 21x18 pixels and, aside from the stylized card that makes up the frame of the bitmap, the usable area is only a dozen pixels across. In desperation I fired up the Medley Interlisp bitmap editor and designed the bitmap myself from scratch. It took just a few minutes and was unexpectedly easy.

I'm pleased with the result, but stunned at how long such a seemingly simple task dragged me.

#WebCard #Interlisp #Lisp

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Over the past days I ran WebCard a bit, reviewed the code, and checked my notes and I'm satisfied with what the system does. Since WebCard is nearly feature complete it's a good time to chart the next steps for wrapping up my RetroChallenge 2024 project.

Aside from some tweaks or cleanups, the only other code to write will set a bitmap for the link icon of Web cards. This is useful to further visually distinguish them from other types of cards such as Text.

WebCard also needs some documentation. I'll expand the README file to explain how to install and use WebCard. A demo notefile with examples of Web cards in a NoteCards hypertext is also useful to show what WebCard does.

#WebCard #Interlisp #Lisp

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WebCard has very limited control over the web browser of the host operating system.

It can only command the browser to visit a URL when the user traverses a Web link or executes the Visit URL menu command. But with no precautions the browser would open a new tab for every visit of the same URL.

To reduce clutter I tweaked WebCard to keep track of visited URLs. The URLVisitedP boolean property of a Web card window indicates whether the associated URL was already visited. The function WCD.TraverseWebLink checks URLVisitedP and visits the URL only if the property is NIL, then sets it to T if it does visit the URL. URLVisitedP is a property of the window rather than the card because, as part of the dynamic session state, NoteCards shouldn't save it in notefiles.

The overall behavior of Web cards and URL visits appears as follows.

Traversing the link of a closed Web card unconditionally visits the URL. Once the card is open, traversing the link again flashes the card to call attention to it but doesn't visit the URL. The Visit URL menu command can force the visit though. Closing a card sets URLVisitedP to NIL, so the next time link traversal reopens the card it triggers a visit.

This should take care of the most common cases of unintentional link traversal, reduce tab clutter, and prepare WebCard for actual usage.

#WebCard #Interlisp #Lisp

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In NoteCards, Text cards are rectangular windows with proportions similar to a post-it note. The Web card type of WebCard inherits from Text, including the default window size. Since a Web card needs only display a URL, the default shape leaves most of the text area blank.

To make Web cards better fit the text area and visually differentiate them from cards of other types I reduced the default height to slighly less than half. The text of a Web card now has enough vertical space for three lines of a wrapped URL. The change makes Web cards closer to badges or tags with a URL as a label than a textual note.

To see the result compare the Web card at the top with the Text card a the bottom:

I made other changes to WebCard, some of which related to the new card shape. First, the WCD.UpdateCardText function now scrolls the card window back to the top to ensure the initial portion of the URL is always in view.

Next, I modified WCD.ValidURLP to check that the lenght of the input URL doesn't exceed 255 characters, the maximum a card property can hold.

Finally, I completed the initialization of Web cards in WCD.MakeWebCard to handle cards that are not immediately displayed upon creation. This is the case of a Web card created via the NoteCards API when the nodisplayflg parameter of NCP.CreateCard is non NIL, instead of interactively by the user. I factored out the code common to displayed and undisplayed cards into the separate function WCD.InitCard.

It took me longer than expected to understand the initialization flow of undisplayed cards. My early attempts produced errors about a missing TEdit window as I unknowingly skipped the initialization of the parent Text type. Calling the parent constructor resolved the issue.

#WebCard #Interlisp #Lisp

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I fixed a URL validation bug of WebCard I have been stuck with for almost a week.

When creating a new card, the function WCD.AskURL brings up a dialog and loops prompting for a URL to go with the card until the input is valid. After the fix the input dialog looks like this, here shown above a new blank card. I entered https, the dialog warned it's not a valid URL, and then I typed a correct one.

WCD.AskURL initially checked only for a null input. I later wrote WCD.ValidURLP to check that the input resembles a URL.

In an attempt to call WCD.ValidURLP from the WCD.AskURL input loop I bumped into a syntax error in the bind clause of an Interlisp iterative statement. The issue eluded me when staring at the code for long. Then the problem suddenly jumped at me: a missing ← symbol.

The bug is now fixed for good and I can move on.

#WebCard #Interlisp #Lisp

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