My favorite Tcl story is a little side note about how Tcl could have been the language of the web[1]
the founding of Netscape occurred at the same time I was deciding where to go in industry when I left Berkeley in 1994. Jim Clarke and Marc Andreessen approached me about the possibility of my joining Netscape as a founder, but I eventually decided against it (they hadn't yet decided to do Web stuff when I talked with them). This is one of the biggest "what if" moments of my career. If I had gone to Netscape, I think there's a good chance that Tcl would have become the browser language instead of JavaScript and the world would be a different place! However, in retrospect I'm not sure that Tcl would actually be a better language for the Web than JavaScript, so maybe the right thing happened.
Too humble Dr. Ousterhout! It would have been a far better language.
I was leading a Tcl project around then, and, though there were some very neat things about the unusual Tcl evaluation model, I wasn't a fan of using it for nontrival work. For example, it wasn't a natural fit for working with graph structures like I had to, and like you might want for browser DOM.
(That said, Tcl would've been much better than JS, and I suspect that Ousterhout would've figured out some smart things to make it good for the browser.)
Maybe 5 years later, I was meeting with Tim-Berners Lee, and I kinda pitched Scheme to him, without planning to, but he was very interested when he asked what I'd been working on.
But then he went and did a conference keynote, in which he promoted Python as the language for ordinary people doing Web stuff. And I think he referenced one of the things I'd written in support of Scheme... as an anti-requirement for his populist vision for the Web. :)
(I wish I could've been involved in that, because I could've made a case for a populist spin on Scheme at the time.)
TCL has an extremely loose runtime model, not to mention everything in the language is basically a string and all that entails.
I’ve been using JavaScript since the early 2000s, just before ES5 dropped.
Like all languages it has its curveballs but it really isn’t all that bad. It simply has oddities due to the quirky nature of the niche it was designed to fill (namely, to be a scripting language that was forgiving to web designers)
I don't get it either? I've only used it occasionally but it has always struck me as a really impressive example of what can be built on minimal (minimalist?) foundations. Its semantics can understood in 5 minutes.
It reminds me of Scheme in this regard. Writing an interpreter or compiler for it would be easily within reach of an undergraduate student. Contrast with other currently popular (more respected?) languages like Rust, C++, Java, C# or even Python.
I've only recently been expose to Typescript and again, I'm really impressed. I haven't encountered a type system so elegant and orthogonal since first being exposed to ML like languages.
Your definition of "semantics" must be different from mine, or you perhaps haven't seen https://javascriptwtf.com/ (linked in a sibling comment)
Your comment actually made me wonder whether those cited artifacts were implementation bugs or actually in the specification and ... lol, this shit reminds me of people who put comments above functions that just restate the function's name: https://tc39.es/ecma262/2024/#sec-addition-operator-plus
> Writing an interpreter or compiler for it would be easily within reach of an undergraduate student
Surely you don't really believe that? Or is the rest of the sentence "... eventually, over the course of their undergraduate career"
The 15th edition of the standard is 816 pages and now includes specifying the Memory Model. What I suspect you mean is "could write a parser for the 1st edition spec from 1997"
I'm claiming that its semantics are simple, not that they've made great choices in the design of the language. For example, I've barely used Javascript, but I think I would have scored fairly highly if that javascriptwft page was turned into a quiz. Most of the examples are fairly transparent once you know the implicit casting rules. I've read certain wtfs associated with C++ or even Java far more puzzling despite years of experience with them.
And yes I do believe that writing an interpreter for Javascript would be no more difficult than doing one for Scheme (which I had to do as a student) - the parser would be more difficult admittedly.
I can find oddities like this in all languages. Arguably C and C++ have more warts, particularly C++ where I always hear people talk about how it’s only reasonable to use a small subset of the language. Also how C/C++ compilers don’t all support the same features of the purported language they compile.
I won’t argue that JS doesn’t have warts - it does and if it wasn’t for backward compatibility I imagine they’d have been removed from the language - but the entries on that website are quite small compared to others - like C and C++ - that I can think of
> not to mention everything in the language is basically a string and all that entail
I disagree with that to at least some extent. Everything is a string works well in TCL because the language is built around that abstraction. It works at least as well as other dynamically typed languages in small projects, and is definitely preferable to Javascript's rather weird weak typing.
It also does async and multi-threading really nicely, and encouraged event driven long before it look off elsewhere.
I used Tcl briefly to build an interface way back with Tcl/Tk, and it is a terrible language. "Everything is a string" is not what you want in a solid programming environment for larger projects. It's a LISP-like gimmick, but without the advantages of LISP.
That said, plain JS is not a good fit for larger projects, either. It really needs TypeScript for that. But it does have some very fast engines.
In the early days at least part of the problem was marketing. The fact that it’s got Java in the name when it’s actually a very different language to Java confused a lot of people. They tried to use the language like Java, had a bad time and concluded the language was bad.
Honestly? I think the biggest cause of JavaScript hate is that a huge percentage of developers have very little choice but to use it.
The web ate almost everything else for a host of reasons, and JavaScript is still the only language that the web natively supports. You can compile to JS or use WASM with occasional callouts to JS, but you can't get away from it entirely.
Most other languages have a greater sense of choice surrounding them. For backend work you can pick pretty much anything, and mobile is still a small enough chunk of the ecosystem that if you really hate Swift you can just find a job that isn't iOS dev. It's not so easy to get out of web dev without dramatically shrinking your job pool.
All I can say is that’s the cost of doing business with the browser being the main platform.
If devs want to interact with it less then focus on moving more to the server. You can still serve HTML and CSS and get a long way without ever touching JS.
It’s no different than other domains where one or two particular languages largely dominate. Like I don’t hear developers decrying the existence of C/C++ every chance they get
I think the hate is entirely unjustified. It’s fine to have preferences but so often it goes beyond that.
I have, but they’re not quite as zealous. The anti JS campaign has been running almost as long as I’ve been using it, which is pushing two decades now.
Now I know why PHP devs sometimes get a little defensive
I think Tcl as it was back then especially would have been a terrible DOM manipulation choice. I love the language but the hacks frameworks like openacs used to use to imitate basic stuff like a list of database records are among the ugliest upvar/up level hacks I've seen.
But that being said it's an incredibly adaptable language and I have zero doubt it could have been adapted to make DOM manipulation ergonomic.
I like Tcl and I think it has some very admirable traits. That being said, I don't even want to picture the hellscape of an ecosystem that would have flourished if it became the language of the web. JS was the better timeline I will admit begrudgingly, and that includes the Scheme timeline as well.
Does Tcl have lexical scoping yet? If not, I'd have to disagree that it would have been a better language. JS is not one of the better languages I know, but it does have lambdas and lexical scoping. And as bad as JS's type system may be, at least it's not stringly-typed.
Funny that Tcl was mentioned today. I've recently been hacking on jimtcl[1] (a small footprint implementation of Tcl) to make objects multi-threaded safe, as that's the core language that folk.computer[2] uses (the main authors are making the interpreter and reactive DB parallelizable rn, so I've been tinkering with how to reduce copying).
Surprised no mentions of sqlite yet :) I've always associated Tcl with sqlite because of how much it is used in their test suite and how you can have a tcl interpreter as a virtual table. Very interesting and seemingly often overlooked little language.
I have used both TCL and Sqlite a fair bit but not both together. I have thought that TCL + in memory Sqlite would make a powerful combination for some tasks but have never actually tried it.
I can't comment on virtual-table shenanigans, but I'll enthusiastically confirm that thought. Not only is an in-memory database powerful and useful for all the obvious reasons, but (I would argue) the Tcl interface to SQLite is perhaps the best relational database API in any language. (Even if it cheats a bit by being an embedded database, as with <https://sqlite.org/tclsqlite.html#function>.) It's easily as synergistic a combination as Tcl and Tk themseves, possibly more.
> Some content has been removed in the second edition of the book because of limits on the number of pages
Lol, wut? The literal only working "buy it now" link is to a PDF. Page limits my ass. Or maybe "Paperback: 660 pages" was dangerously close to the Devil himself springing forth from the pages and turning all your codebase into VBScript
I have known about Tcl since the 1990s. I remember Stallman advising not use it. Maybe he did not like the license?
Yesterday, over 30 years later I was forced to write my first code. Noticed that a Cisco switch had an incredibly bad ssh implemtation, so to automate some commands I needed expect scripting. Expect is based on Tcl.
"a language for extensions should... be a real programming
language, designed for writing and maintaining substantial programs...
The first Emacs used a string-processing language, TECO, which was
inadequate. We made it serve, but it kept getting in our way. It
made maintenance harder, and it made extensions harder to write...
Tcl was not designed to be a serious programming language. It was
designed to be a "scripting language", on the assumption that a
"scripting language" need not try to be a real programming language.
So Tcl doesn't have the capabilities of one. It lacks arrays; it
lacks structures from which you can make linked lists. It fakes
having numbers, which works, but has to be slow. Tcl is ok for
writing small programs, but when you push it beyond that, it becomes
insufficient.
Tcl has a peculiar syntax that appeals to hackers because of its
simplicity. But Tcl syntax seems strange to most users."
> It fakes having numbers, which works, but has to be slow.
This hasn't been the case for 25 years, since the 8.0 release.
Tcl will store data internally in whatever format it was last used, and only convert if needed. Good coding practice pays attention to this to avoid "shimmering" a value back and forth between different internal representations unnecessesarily.
> It lacks arrays;
It does have associative arrays; and lists when used appropriately can fulfil many roles that would otherwise have been implemented in an array in another language
And tcllib[0], a collection of utilities commonly used with tcl, provides support for a number of different and complex data structions [1], many of which are written in C, not just more tcl scripts.
It's worth noting that Stallman's criticism linked above is more than three decades out of date. As with any programming tool, once you go beyond a superficial understanding of basic syntax, it can serve as a a very expressive and sufficient language.
If I recall correctly, I think he was just more of a lisp fan and promoted something like Guile or E-Lisp. It may have been license as well. I'm not very sure about it though.
I think he was worried about Sun Microsystems involvement[0] w Tcl when John Ousterhout went there[1], too. But mostly seems like a collection of unsolicited strawmen[2]. Also probably love-of-lisp.
I own the first edition of this book and it's really good. I've written a few tcl scripts with it, but nothing major. Python just has the better ecosystem now for my needs. I might use tcl if I needed something really small though.
I'm aware, but that kind of defeats the point (at least to me). If I want to build out some cute DSL for a project, it would just be with the small tcl interpreter.
Nice memories of having our own AOLServer like clone, Vignette, routinely writing extensions in C, and also why since 2003 I tend to avoid languages without JIT/AOT unless it is for banal OS and application scripting task.
I may have to learn its other half, Tk, as a side project of mine is starting to feel less like something I can pull off as a "wizard" on the command line. I had wrestled with wxPython many moons ago and, while I got through it, I felt like I had perhaps taken a wrong turn.
As a side note, while I have seen many UI elements over the decades, I cannot help but think that the wizard (or whatever you would like to call it) has somehow escaped being listed as a standard UI element. Perhaps it is too large to count for many.
but I'm not seeing an easy binary download --- used to be that the availability of a pre-compiled version, nicely packaged which would install easily on one's platform of choice made it wonderfully accessible to new users.
I was going to say releases are published to Sorceforge[0] but indeed those look to be all src too. That said: I’d be surprised to find a distro that doesn’t have Tcl available in whatever package manager(s) they support.
I would be interested to know if anyone ever built anything non-trivial that didn't turn into a complete mess due to TCL's general type-flimsyness and "everything is a string" philosophy.
TCL stands for "tool command language." In terms of non trivial tools that have been built with it there have been several. AOLServer, MacPorts, tons of CAD and engineering software. There's a whole wikipedia category just for this:
Aside from that there was Tk which was used to create many UIs in an era where scripted UIs were otherwise painful to create and maintain. A prominent example here is 'xconfig' from the linux kernel.
Like any good environment a little bit of practice with it can see you overcome it's apparent shortcomings and see you producing reliable and useful software in far less time that you might have in a more traditional way.
Programming is about trade offs. It's not a checklist of "good ideas."
My big project at work uses pytk only because it was already included with the anaconda distribution. It works fine, it's not pretty but it's just an internal engineering tool.
The GUI of Pure Data (https://en.m.wikipedia.org/wiki/Pure_Data) is written in Tcl/Tk. In the 90s this was a popular and sensible choice, but not so much in 2025 :) I still have hopes that one day we'll manage to replace it with something better.
(There are alternative implementations of Pd, such as PurrData or PlugData, that use different UI frameworks.)
I have been looking at using both of those. I have used TCL before but it was a while back, but Lazarus does have a visual designer which I have played with a bit.
I am not sure which makes producing cross platform binaries easier. I ran into a few issues the last time I tried TclKit I ran into problems so Starkits may not be an easy solution anymore.
Lazarus is excellent. It is very user friendly once you get the hang of it, and you can use Delphi books to learn the language. It also produces static binaries that make it easy to distribute your software.
Yes, both Tcl/Tk and Python/Tk are great in 2025 for doing simple GUI programming and this fact does make me sad. Or perhaps we've found the global minimum? Who knows.
> I would be interested to know if anyone ever built anything non-trivial that didn't turn into a complete mess due to TCL's general type-flimsyness and "everything is a string" philosophy.
Both MacPorts CLI client[0] and ports tree[0] have used it successfully for many years.
Regarding:
"everything is a string" philosophy
That can be said for the vast majority of Unix-like OS user-space programs.
TCL/tk is used for the vast majority of integrated circuit verification tools. This is used by all the large manufacturers, even competitors use each others tools.
Absolutely huge codebases, there's git blames that go back to the 80s.
Someone did a nice job of porting your revision control data. It would be fascinating to know what the previous systems were - probably svn or cvs, maybe both in chronological order, but before that?
I know in the late 90s, early 2000s they were Vignette shop, back when it was a Tcl application. Can only imagine their relief getting to carry over their tcl knowledge while no longer having to suffer with Vignette. I don't think I've ever heard anyone that actually liked Vignette.
I don't recall any groups using Vignette at AOL during that time. It may be that one of the acquisitions used it prior to being acquired, but again, I never heard about it.
CNN.com was definitely using the StoryBuilder part up until the 2005 redesign as it's noted in the source of each and every article, and there were some tell-tale droppings on the home page as well.
A whole company, with our in-house version of AOLServer, using Apache and IIS plugins for the Tcl interpreter, running across AIX, HP-UX, Solaris, Windows 2000/NT, Red-Hat Linux, with our own ActiveRecord like approach (a decade before Rails happened), with connectors for Sybase SQLServer, MS SQLServer, Informix, Oracle, DB2, Access, doing code generation from Oracle based ER diagrams, and an IDE written in VB 6.
Which became a business unit from Altitude Software, eventually due to our MSFT partnership level we got access to .NET builds before it was known to the world, as one of the key Portuguese partners, and started to replicate our stack in .NET, based on the learnings from our Tcl based product.
The founders and core devs, from the original startup, eventually left to create their no code/low code platform, based on the learnings from both technology stacks, what they managed to achieve, and what was not done quite right, out of that OutSystems was born, one of the most successful Portuguese IT companies from the last 20 years.
I think using Tcl for that startup on a tiny Lisbon basement back in the late 1990's, turned out quite alright.
There is no big difference between TCL and other languages like Python in this respect. Yes, TCL stores everything as a string, but it also assigns a type when the data is used. If you need a defined type, you can use structures; there are even classes/objects available as packages.
Yep! It's called shimmering. The way it works is it has a string and internal representation. When the internal representation is modified it invalidates the string version. If the string version is needed later it'll regenerate the string representation. That way it can always be used as a string, but internally it is pretty efficient when it stays as the same type.
You’re misunderstanding. Dynamic languages inherently have a single type that is checked _at runtime_. Store it in a string, store it in a struct. It doesn’t matter.
And in Tcl the runtime type is computed at time of use. An optimized Tcl could cache an integer with a string that represents an int to avoid that cost.
Nevertheless, a runtime type tag is an optimization. That doesn’t make Bob’s statement any less true.
Because Python is “strong typed” vs “weak typed” for Tcl?
$ tclsh8.6
% expr 1 + 2
3
% expr 3 + “hey there”
invalid bareword “hey”
in expression “1 + hey there”;
should be “$hey” or “{hey}” or “hey(…)” or …
vs.
$ python3.11
>>> 1 + 2
3
>>> 1 + “hey there”
Traceback (most recent call last):
File “<stdin>”, line 1, in <module>
TypeError: unsupported operand type(s) for +: ‘int’ and ‘str’
I don’t really see a difference. Both checked types at runtime. Clearly Tcl can check types at runtime, even though it represents everything as a string. Whether all commands do so is another story. But, not all functions in Python check types before trying to do things that don’t make sense, either. So…
100's of Klines of code in continuous development over the last 10 years, still currently maintained and continually adapted for new use cases in Electronic Design Automation (EDA) for logical and physical chip design and verification.
Of course it's possible to create "write-only" code in tcl. But tcl is hardly unique in that respect. Good code design and coding practices help to avoid most issues just as in many other languages.
"Everything is a string" (EIAS) is not what leads to a complete mess; it's failing to go beyond an initial, superficial understanding of the syntax and language capability and general lack of discipline that lead to un-fixable messes.
For FPGA IDEs, a lot of the background is just tcl scripts so you can easily write your own build scripts. You could theoretically put them into your CI pipeline but I don't know if anyone actually does this.
Many of the big EDA (Electronic Design Automation) tools continue to use tcl for the command line interface. Some users have created quite complex, customizable design flows spanning multiple tools and even development infrastructure (much, much more than just "stitching tools together) using tcl.
It is still actively developed and used, yeah. People tend to mention the fpga scene most, tcl is the predominant language there, but I use it mostly with or along side audio/visual software.
Expect is very cool and useful. I have used it some.
I read almost the full Expect book by Don Libes, the author of Expect, several years ago. He had a unique and very interesting style of writing, in that book.
Yes, so popular that there are also ports of Expect to some other languages, such as Python and others.
My favorite Tcl story is a little side note about how Tcl could have been the language of the web[1]
Too humble Dr. Ousterhout! It would have been a far better language.1 - https://pldb.io/blog/JohnOusterhout.html
I was leading a Tcl project around then, and, though there were some very neat things about the unusual Tcl evaluation model, I wasn't a fan of using it for nontrival work. For example, it wasn't a natural fit for working with graph structures like I had to, and like you might want for browser DOM.
(That said, Tcl would've been much better than JS, and I suspect that Ousterhout would've figured out some smart things to make it good for the browser.)
Maybe 5 years later, I was meeting with Tim-Berners Lee, and I kinda pitched Scheme to him, without planning to, but he was very interested when he asked what I'd been working on.
But then he went and did a conference keynote, in which he promoted Python as the language for ordinary people doing Web stuff. And I think he referenced one of the things I'd written in support of Scheme... as an anti-requirement for his populist vision for the Web. :)
(I wish I could've been involved in that, because I could've made a case for a populist spin on Scheme at the time.)
Why does JavaScript get some much hate?
TCL has an extremely loose runtime model, not to mention everything in the language is basically a string and all that entails.
I’ve been using JavaScript since the early 2000s, just before ES5 dropped.
Like all languages it has its curveballs but it really isn’t all that bad. It simply has oddities due to the quirky nature of the niche it was designed to fill (namely, to be a scripting language that was forgiving to web designers)
"Why does JavaScript get some much hate?"
I don't get it either? I've only used it occasionally but it has always struck me as a really impressive example of what can be built on minimal (minimalist?) foundations. Its semantics can understood in 5 minutes.
It reminds me of Scheme in this regard. Writing an interpreter or compiler for it would be easily within reach of an undergraduate student. Contrast with other currently popular (more respected?) languages like Rust, C++, Java, C# or even Python.
I've only recently been expose to Typescript and again, I'm really impressed. I haven't encountered a type system so elegant and orthogonal since first being exposed to ML like languages.
> Its semantics can understood in 5 minutes.
Your definition of "semantics" must be different from mine, or you perhaps haven't seen https://javascriptwtf.com/ (linked in a sibling comment)
Your comment actually made me wonder whether those cited artifacts were implementation bugs or actually in the specification and ... lol, this shit reminds me of people who put comments above functions that just restate the function's name: https://tc39.es/ecma262/2024/#sec-addition-operator-plus
> Writing an interpreter or compiler for it would be easily within reach of an undergraduate student
Surely you don't really believe that? Or is the rest of the sentence "... eventually, over the course of their undergraduate career"
The 15th edition of the standard is 816 pages and now includes specifying the Memory Model. What I suspect you mean is "could write a parser for the 1st edition spec from 1997"
I'm claiming that its semantics are simple, not that they've made great choices in the design of the language. For example, I've barely used Javascript, but I think I would have scored fairly highly if that javascriptwft page was turned into a quiz. Most of the examples are fairly transparent once you know the implicit casting rules. I've read certain wtfs associated with C++ or even Java far more puzzling despite years of experience with them.
And yes I do believe that writing an interpreter for Javascript would be no more difficult than doing one for Scheme (which I had to do as a student) - the parser would be more difficult admittedly.
I can find oddities like this in all languages. Arguably C and C++ have more warts, particularly C++ where I always hear people talk about how it’s only reasonable to use a small subset of the language. Also how C/C++ compilers don’t all support the same features of the purported language they compile.
I won’t argue that JS doesn’t have warts - it does and if it wasn’t for backward compatibility I imagine they’d have been removed from the language - but the entries on that website are quite small compared to others - like C and C++ - that I can think of
> not to mention everything in the language is basically a string and all that entail
I disagree with that to at least some extent. Everything is a string works well in TCL because the language is built around that abstraction. It works at least as well as other dynamically typed languages in small projects, and is definitely preferable to Javascript's rather weird weak typing.
It also does async and multi-threading really nicely, and encouraged event driven long before it look off elsewhere.
I used Tcl briefly to build an interface way back with Tcl/Tk, and it is a terrible language. "Everything is a string" is not what you want in a solid programming environment for larger projects. It's a LISP-like gimmick, but without the advantages of LISP.
That said, plain JS is not a good fit for larger projects, either. It really needs TypeScript for that. But it does have some very fast engines.
In the early days at least part of the problem was marketing. The fact that it’s got Java in the name when it’s actually a very different language to Java confused a lot of people. They tried to use the language like Java, had a bad time and concluded the language was bad.
Honestly? I think the biggest cause of JavaScript hate is that a huge percentage of developers have very little choice but to use it.
The web ate almost everything else for a host of reasons, and JavaScript is still the only language that the web natively supports. You can compile to JS or use WASM with occasional callouts to JS, but you can't get away from it entirely.
Most other languages have a greater sense of choice surrounding them. For backend work you can pick pretty much anything, and mobile is still a small enough chunk of the ecosystem that if you really hate Swift you can just find a job that isn't iOS dev. It's not so easy to get out of web dev without dramatically shrinking your job pool.
All I can say is that’s the cost of doing business with the browser being the main platform.
If devs want to interact with it less then focus on moving more to the server. You can still serve HTML and CSS and get a long way without ever touching JS.
It’s no different than other domains where one or two particular languages largely dominate. Like I don’t hear developers decrying the existence of C/C++ every chance they get
I think the hate is entirely unjustified. It’s fine to have preferences but so often it goes beyond that.
FWIW, I agree totally, and I don't find JavaScript to be bad at all.
> Like I don’t hear developers decrying the existence of C/C++ every chance they get
I guess you haven't encountered the monkey zoo of rust cultists yet
I have, but they’re not quite as zealous. The anti JS campaign has been running almost as long as I’ve been using it, which is pushing two decades now.
Now I know why PHP devs sometimes get a little defensive
This is a classic: https://www.destroyallsoftware.com/talks/wat
"Brooklyn Nine-Nine" said it: https://www.youtube.com/watch?v=H1-GDlzODzc&t=27s
Guess I’m garbage :(
The joke is that it comes down to prejudice.
[flagged]
You lost me once you compared an alternative technological solution to racism.
Would you have preferred ‘let them eat cake’?
‘Just do something else’ is not a valid response to ‘I would like to do this, but am unreasonably prevented from doing it.’
I think Tcl as it was back then especially would have been a terrible DOM manipulation choice. I love the language but the hacks frameworks like openacs used to use to imitate basic stuff like a list of database records are among the ugliest upvar/up level hacks I've seen.
But that being said it's an incredibly adaptable language and I have zero doubt it could have been adapted to make DOM manipulation ergonomic.
If I remember correctly early HTML specs actually used Tcl as an example for script tag content.
It was definitely possible that Tcl could have ended up the web sripting language.
> It would have been a far better language.
I like Tcl and I think it has some very admirable traits. That being said, I don't even want to picture the hellscape of an ecosystem that would have flourished if it became the language of the web. JS was the better timeline I will admit begrudgingly, and that includes the Scheme timeline as well.
Does Tcl have lexical scoping yet? If not, I'd have to disagree that it would have been a better language. JS is not one of the better languages I know, but it does have lambdas and lexical scoping. And as bad as JS's type system may be, at least it's not stringly-typed.
Allow me to introduce you to upvar https://www.tcl-lang.org/man/tcl9.0/TclCmd/upvar.html and its uplevel friend https://www.tcl-lang.org/man/tcl9.0/TclCmd/uplevel.html
I cannot possibly imagine the horrors of frontend frameworks that can grab values, or execute, in someone else's context willy nilly
Exactly, it's dynamic scoping. As far as I know, Tcl is the only language that still has this skeleton in its closet.
With great power comes great responsibility :-)
In that world, Netscape might have also acquired Naviserver instead of AOL. Wasn't the plan at Netscape to make money on their server software?
Funny that Tcl was mentioned today. I've recently been hacking on jimtcl[1] (a small footprint implementation of Tcl) to make objects multi-threaded safe, as that's the core language that folk.computer[2] uses (the main authors are making the interpreter and reactive DB parallelizable rn, so I've been tinkering with how to reduce copying).
[1] https://github.com/msteveb/jimtcl [2] https://folk.computer/
Surprised no mentions of sqlite yet :) I've always associated Tcl with sqlite because of how much it is used in their test suite and how you can have a tcl interpreter as a virtual table. Very interesting and seemingly often overlooked little language.
I have used both TCL and Sqlite a fair bit but not both together. I have thought that TCL + in memory Sqlite would make a powerful combination for some tasks but have never actually tried it.
> have a tcl interpreter as a virtual table
Do you mean this: https://sqlite.org/src/file/src/test_tclvar.c ?
I can't comment on virtual-table shenanigans, but I'll enthusiastically confirm that thought. Not only is an in-memory database powerful and useful for all the obvious reasons, but (I would argue) the Tcl interface to SQLite is perhaps the best relational database API in any language. (Even if it cheats a bit by being an embedded database, as with <https://sqlite.org/tclsqlite.html#function>.) It's easily as synergistic a combination as Tcl and Tk themseves, possibly more.
> Some content has been removed in the second edition of the book because of limits on the number of pages
Lol, wut? The literal only working "buy it now" link is to a PDF. Page limits my ass. Or maybe "Paperback: 660 pages" was dangerously close to the Devil himself springing forth from the pages and turning all your codebase into VBScript
I have known about Tcl since the 1990s. I remember Stallman advising not use it. Maybe he did not like the license?
Yesterday, over 30 years later I was forced to write my first code. Noticed that a Cisco switch had an incredibly bad ssh implemtation, so to automate some commands I needed expect scripting. Expect is based on Tcl.
Per http://vanderburg.org/old_pages/Tcl/war/0000.html
Stallman's argument at the time was:
"a language for extensions should... be a real programming language, designed for writing and maintaining substantial programs...
The first Emacs used a string-processing language, TECO, which was inadequate. We made it serve, but it kept getting in our way. It made maintenance harder, and it made extensions harder to write...
Tcl was not designed to be a serious programming language. It was designed to be a "scripting language", on the assumption that a "scripting language" need not try to be a real programming language. So Tcl doesn't have the capabilities of one. It lacks arrays; it lacks structures from which you can make linked lists. It fakes having numbers, which works, but has to be slow. Tcl is ok for writing small programs, but when you push it beyond that, it becomes insufficient.
Tcl has a peculiar syntax that appeals to hackers because of its simplicity. But Tcl syntax seems strange to most users."
> It fakes having numbers, which works, but has to be slow.
This hasn't been the case for 25 years, since the 8.0 release. Tcl will store data internally in whatever format it was last used, and only convert if needed. Good coding practice pays attention to this to avoid "shimmering" a value back and forth between different internal representations unnecessesarily.
> It lacks arrays;
It does have associative arrays; and lists when used appropriately can fulfil many roles that would otherwise have been implemented in an array in another language
And tcllib[0], a collection of utilities commonly used with tcl, provides support for a number of different and complex data structions [1], many of which are written in C, not just more tcl scripts.
It's worth noting that Stallman's criticism linked above is more than three decades out of date. As with any programming tool, once you go beyond a superficial understanding of basic syntax, it can serve as a a very expressive and sufficient language.
[0] <https://www.tcl-lang.org/software/tcllib>
[1] <https://core.tcl-lang.org/tcllib/doc/trunk/embedded/md/toc.m...> (see: Data structures)
If I recall correctly, I think he was just more of a lisp fan and promoted something like Guile or E-Lisp. It may have been license as well. I'm not very sure about it though.
I think he was worried about Sun Microsystems involvement[0] w Tcl when John Ousterhout went there[1], too. But mostly seems like a collection of unsolicited strawmen[2]. Also probably love-of-lisp.
[0] That any proximity to commerce is evil?
[1] https://en.wikipedia.org/wiki/John_Ousterhout
[2] https://vanderburg.org/old_pages/Tcl/war/
Most IOS implementations (classic, XE, XR) also have tclsh, a tcl REPL (that can also interact with the file systems to load and write scripts).
I own the first edition of this book and it's really good. I've written a few tcl scripts with it, but nothing major. Python just has the better ecosystem now for my needs. I might use tcl if I needed something really small though.
A TCL interpreter is packaged with Python in the tkinter library:
import tkinter
tcl=tkinter.Tcl()
tcl.eval('puts "Hello, world!"')
I'm aware, but that kind of defeats the point (at least to me). If I want to build out some cute DSL for a project, it would just be with the small tcl interpreter.
Nice memories of having our own AOLServer like clone, Vignette, routinely writing extensions in C, and also why since 2003 I tend to avoid languages without JIT/AOT unless it is for banal OS and application scripting task.
I may have to learn its other half, Tk, as a side project of mine is starting to feel less like something I can pull off as a "wizard" on the command line. I had wrestled with wxPython many moons ago and, while I got through it, I felt like I had perhaps taken a wrong turn.
As a side note, while I have seen many UI elements over the decades, I cannot help but think that the wizard (or whatever you would like to call it) has somehow escaped being listed as a standard UI element. Perhaps it is too large to count for many.
There is a source release at:
https://www.tcl-lang.com/software/tcltk/9.0.html
but I'm not seeing an easy binary download --- used to be that the availability of a pre-compiled version, nicely packaged which would install easily on one's platform of choice made it wonderfully accessible to new users.
Is that not a focus of the project these days?
Looks like binary downloads are on another page and not necessarily made by tcl-lang
https://www.tcl-lang.com/software/tcltk/bindist.html
From that page:
- Android 8.6.10 https://androwish.org/download/index.html
- Activestate seems to require account creation: https://www.activestate.com/pricing/
- Windows, nightly build of 9.0.2 from 15 February: https://gitlab.com/teclabat/tcltk/-/packages/34837768
- Windows 8.6.7 https://www.irontcl.com/index.html
This looks like the link I was looking for: Windows 9.0.1: https://www.tcl3d.org/bawt/download.html#tclpure which links to: https://www.tcl3d.org/bawt/download/Tcl-BI/SetupTcl-BI-9.0.1...
I was going to say releases are published to Sorceforge[0] but indeed those look to be all src too. That said: I’d be surprised to find a distro that doesn’t have Tcl available in whatever package manager(s) they support.
[0] https://sourceforge.net/projects/tcl/
Managed to find two Windows binaries as noted elsethread.
It would be nice to have found one for the Mac....
Homebrew has it
> this immensely flexible and versatile language
I would be interested to know if anyone ever built anything non-trivial that didn't turn into a complete mess due to TCL's general type-flimsyness and "everything is a string" philosophy.
Cisco iOS[0], F5 iRules[1], Tealeaf network monitoring/processing[2][3], Fidessa[4][5], …
[0] https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ios_tcl/co...
[1] https://community.f5.com/kb/technicalarticles/irules-concept...
[2] https://www.acoustic.com/tealeaf
[3] https://help.goacoustic.com/hc/en-us/articles/360043279654-C...
[4] https://www.cmegroup.com/solutions/market-tech-and-data-serv...
[5] http://www.services.fidessa.com/brochures/_training/VF043.pd...
TCL stands for "tool command language." In terms of non trivial tools that have been built with it there have been several. AOLServer, MacPorts, tons of CAD and engineering software. There's a whole wikipedia category just for this:
https://en.wikipedia.org/wiki/Category:Free_software_program...
Aside from that there was Tk which was used to create many UIs in an era where scripted UIs were otherwise painful to create and maintain. A prominent example here is 'xconfig' from the linux kernel.
Like any good environment a little bit of practice with it can see you overcome it's apparent shortcomings and see you producing reliable and useful software in far less time that you might have in a more traditional way.
Programming is about trade offs. It's not a checklist of "good ideas."
My big project at work uses pytk only because it was already included with the anaconda distribution. It works fine, it's not pretty but it's just an internal engineering tool.
It's Tcl now not TCL. No longer an acronym. It hasn't been TCL for years.
The GUI of Pure Data (https://en.m.wikipedia.org/wiki/Pure_Data) is written in Tcl/Tk. In the 90s this was a popular and sensible choice, but not so much in 2025 :) I still have hopes that one day we'll manage to replace it with something better.
(There are alternative implementations of Pd, such as PurrData or PlugData, that use different UI frameworks.)
> In the 90s this was a popular and sensible choice, but not so much in 2025 :)
Infuriatingly, Tcl/Tk (and other things which use Tk) is still light years easier for doing basic GUI programming than anything that exists in 2025.
How the hell can decades have elapsed and Tcl/Tk, Hypercard and VB6 are still vastly better for GUI development than anything we currently have?
In the same vein, Lazarus/FreePascal is an excellent open source and cross platform Delphi clone.
I have been looking at using both of those. I have used TCL before but it was a while back, but Lazarus does have a visual designer which I have played with a bit.
I am not sure which makes producing cross platform binaries easier. I ran into a few issues the last time I tried TclKit I ran into problems so Starkits may not be an easy solution anymore.
Lazarus is excellent. It is very user friendly once you get the hang of it, and you can use Delphi books to learn the language. It also produces static binaries that make it easy to distribute your software.
Yes, both Tcl/Tk and Python/Tk are great in 2025 for doing simple GUI programming and this fact does make me sad. Or perhaps we've found the global minimum? Who knows.
git-gui and gitk are also written in Tcl/Tk.
>> this immensely flexible and versatile language
> I would be interested to know if anyone ever built anything non-trivial that didn't turn into a complete mess due to TCL's general type-flimsyness and "everything is a string" philosophy.
Both MacPorts CLI client[0] and ports tree[0] have used it successfully for many years.
Regarding:
That can be said for the vast majority of Unix-like OS user-space programs.0 - https://github.com/macports/macports-base
1 - https://github.com/macports/macports-ports
Flightaware, at one point, had a lot of Tcl code
https://www.flightaware.com/about/code/
This is still very much the case. Although most new code is written in other languages, Tcl still has a substantial presence.
TCL/tk is used for the vast majority of integrated circuit verification tools. This is used by all the large manufacturers, even competitors use each others tools.
Absolutely huge codebases, there's git blames that go back to the 80s.
Someone did a nice job of porting your revision control data. It would be fascinating to know what the previous systems were - probably svn or cvs, maybe both in chronological order, but before that?
Not my codebase, but they were SVN (still migrating, lol). No clue about before then, though.
For many years every web page at CNN and all web email at AOL was hosted by AOLserver and coded in TCL. It was not a mess.
I know in the late 90s, early 2000s they were Vignette shop, back when it was a Tcl application. Can only imagine their relief getting to carry over their tcl knowledge while no longer having to suffer with Vignette. I don't think I've ever heard anyone that actually liked Vignette.
I don't recall any groups using Vignette at AOL during that time. It may be that one of the acquisitions used it prior to being acquired, but again, I never heard about it.
CNN.com was definitely using the StoryBuilder part up until the 2005 redesign as it's noted in the source of each and every article, and there were some tell-tale droppings on the home page as well.
Wavesurfer was a great program written Tcl/Tk, with an audio processing library called "snack" in C with Tcl wrappers.
https://en.wikipedia.org/wiki/WaveSurfer
A whole company, with our in-house version of AOLServer, using Apache and IIS plugins for the Tcl interpreter, running across AIX, HP-UX, Solaris, Windows 2000/NT, Red-Hat Linux, with our own ActiveRecord like approach (a decade before Rails happened), with connectors for Sybase SQLServer, MS SQLServer, Informix, Oracle, DB2, Access, doing code generation from Oracle based ER diagrams, and an IDE written in VB 6.
Which became a business unit from Altitude Software, eventually due to our MSFT partnership level we got access to .NET builds before it was known to the world, as one of the key Portuguese partners, and started to replicate our stack in .NET, based on the learnings from our Tcl based product.
The founders and core devs, from the original startup, eventually left to create their no code/low code platform, based on the learnings from both technology stacks, what they managed to achieve, and what was not done quite right, out of that OutSystems was born, one of the most successful Portuguese IT companies from the last 20 years.
I think using Tcl for that startup on a tiny Lisbon basement back in the late 1990's, turned out quite alright.
Sqlite started as a tcl extension. That isn't exactly your question, but I thought it was closely related.
And, AIUI, the monstrous test suite of SQLite is all in Tcl (which totally jives given your fact; they're obviously fans)
There is no big difference between TCL and other languages like Python in this respect. Yes, TCL stores everything as a string, but it also assigns a type when the data is used. If you need a defined type, you can use structures; there are even classes/objects available as packages.
Does it still do this? I thought they changed this many years ago?
Yep! It's called shimmering. The way it works is it has a string and internal representation. When the internal representation is modified it invalidates the string version. If the string version is needed later it'll regenerate the string representation. That way it can always be used as a string, but internally it is pretty efficient when it stays as the same type.
That is absolutely not how Python works. Python values are typed.
> "a dynamically typed language is a statically typed language with only one static type."
Yes but we are not talking about static types...
You’re misunderstanding. Dynamic languages inherently have a single type that is checked _at runtime_. Store it in a string, store it in a struct. It doesn’t matter.
The runtime values have tags that denote their runtime type. They are not of a single type. You are talking about static types.
And in Tcl the runtime type is computed at time of use. An optimized Tcl could cache an integer with a string that represents an int to avoid that cost.
Nevertheless, a runtime type tag is an optimization. That doesn’t make Bob’s statement any less true.
What you said above is correct but is not related to what was being discussed before.
How is it not related?
Because Python is “strong typed” vs “weak typed” for Tcl?
vs. I don’t really see a difference. Both checked types at runtime. Clearly Tcl can check types at runtime, even though it represents everything as a string. Whether all commands do so is another story. But, not all functions in Python check types before trying to do things that don’t make sense, either. So…I can see a difference that I can understand the Python’s error message, the Tcl’s one not so much.
Error message usefulness is not a strict requirement of type systems.
> Python values are typed.
So are Tcl values.
100's of Klines of code in continuous development over the last 10 years, still currently maintained and continually adapted for new use cases in Electronic Design Automation (EDA) for logical and physical chip design and verification.
Of course it's possible to create "write-only" code in tcl. But tcl is hardly unique in that respect. Good code design and coding practices help to avoid most issues just as in many other languages.
"Everything is a string" (EIAS) is not what leads to a complete mess; it's failing to go beyond an initial, superficial understanding of the syntax and language capability and general lack of discipline that lead to un-fixable messes.
For FPGA IDEs, a lot of the background is just tcl scripts so you can easily write your own build scripts. You could theoretically put them into your CI pipeline but I don't know if anyone actually does this.
A lot of old GUIs are built on Tcl/Tk, lots of people use matplotlib which I think uses it by default.
what is your definition of non trivial?
Search upthread for "Klines" and "80s"
I had this book, it's well written.
Is Tcl still a thing? At my first job I extended with a set of data-processing commands.
Many of the big EDA (Electronic Design Automation) tools continue to use tcl for the command line interface. Some users have created quite complex, customizable design flows spanning multiple tools and even development infrastructure (much, much more than just "stitching tools together) using tcl.
It is still actively developed and used, yeah. People tend to mention the fpga scene most, tcl is the predominant language there, but I use it mostly with or along side audio/visual software.
I used it for scripting routers, more than anything else.
I guess expect became something almost popular enough to be considered external to TCL in the end, too.
Expect is very cool and useful. I have used it some.
I read almost the full Expect book by Don Libes, the author of Expect, several years ago. He had a unique and very interesting style of writing, in that book.
Yes, so popular that there are also ports of Expect to some other languages, such as Python and others.
Best of the best. Bought it.