9 ms·

Learn X in Y minutes – Tcl

94 points by notduncansmith 11y ago

meeper16 11y ago
Tcl is awesome.
- tonyjstark 11y ago
  can you elaborate? I always wonder if I should learn it, how it would make me think in new ways and how I would use it. Tcl looks strange and that makes it very interesting for me so how do you use it and why do you use Tcl for it?
  - meeper16 11y ago
    I do a lot of text mining and it's one of the most efficient languages I've used over the years for doing things like this.
    - a8da6b0c91d 11y ago
      That's an unusual assertion. Perl has much better facilities for working with unicode, and many other advanced facilities for parsing and so forth.
      - bch 11y ago
        > Perl has much better facilities for working with unicode Which facilities are those ? > many other advanced facilities for parsing Be curious to hear what those are, but note that Tcl is hilariously simple to extend and build up custom constructs to suit ones needs.
        eviltwinskippy 11y ago
        Not to mention that Tcl has Unicode in the core, has had Unicode in the core for at least 8 years, and the long and short is that EVERY string operation is Unicode aware. You can have unicode procedure names, if that was your fancy.
        bch 11y ago
        ...right, which is why I was wondering where Perl's support is superior. Tcl's support isn't perfect nor complete, but it's still pretty impressive.
      - wrenky 11y ago
        I would like to see what advanced facilities perl has for text parsing that TCL doesn't!
        kbenson 11y ago
        Me too, but I suspect it might take someone of tchrist's level with experience in both languages to give a good answer. I would be interested in how TCL handles the issues tchirst has to deal with outlined in his famous SO post[1]. Note: If you read that post and think, "Wow, Perl requires a lot of setup for unicode and TCP doesn't require nearly as much" without understanding the specifics of why each step is there, and how TCL handles the same issue, you are likely underthinking the issue. 1: http://stackoverflow.com/questions/6162484/why-does-modern-perl-avoid-utf-8-by-default http://stackoverflow.com/questions/6162484/why-does-modern-p...
  - _pmf_ 11y ago
    It offers the syntactic freedom of Lisp/Scheme without the parentheses.
    - _ph_ 11y ago
      The top level of parenthesis-es is left out, the other levels replaced by brackets :). But joking aside, I greatly enjoy both Lisp and Tcl as languages.
      - a8da6b0c91d 11y ago
        A huge, seriously annoying problem with TCL is lack of deterministic cleanup for resources. If you don't manually close a filehandle, for example, it will leak. Doing this sort of bookkeeping in 2015 is infuriating.
        sebcat 11y ago
        proc with {file as name block} { uplevel 1 [list set $name $file] uplevel 1 [list eval $block] uplevel 1 [list close $file] } with [open foo.txt w] as file { puts $file "Hello, World!" } I'm sure it's possible to do it in a cleaner way without [set], but my Tcl is a bit rusty.
        a8da6b0c91d 11y ago
        Still leaks on an exception. That's also an annoying construct to be forced to use.
        nilkn 11y ago
        You could easily wrap the middle uplevel in a catch block to handle exceptions, and this sort of "with" construct is pretty common in a lot of very popular languages today. While it would be nice if this were baked into the language, it's pretty astonishing how extensible Tcl is without even having to touch the realm of C extensions.
  - reacweb 11y ago
    TCL/TK is incredibly powerful to put a GUI in front of a bunch of scripts. You can easily bind a regexp in a log file to events that update widgets. I wish I had learned it 20 years ago.
    - ash 11y ago
      Could you give an example of that?
      - mdaniel 11y ago
        If by "that" you mean an example of a GUI on top of scripts, the `git gui` and `gitk` that ship with git are in Tcl/Tk and shell out to the git commands that do the work As others have mentioned, they are very, very not "native UI" friendly - OSX is an especially bad instance - but they do run on all of Git's platforms without a 20MB runtime to go along with them. If Tk's widgets were just a little less harsh, those two would absolutely be my go-to graphical git clients.
  - stevekemp 11y ago
    This is a great introduction, by antirez of redis-fame. http://antirez.com/articoli/tclmisunderstood.html http://antirez.com/articoli/tclmisunderstood.html
  - msravi 11y ago
    Tcl is also the de-facto default language for almost all VLSI tools
  - wainstead 11y ago
    This post occasionally makes the rounds and is an enlightening read: http://antirez.com/articoli/tclmisunderstood.html http://antirez.com/articoli/tclmisunderstood.html
  - wrenky 11y ago
    We use TCL for almost everything that isn't C/C++, its insanely flexible. You can completely redefine the syntax if you want as there are NO keywords. Meta programming is easy, as all TCL commands follow the same format- Its only con is the lack of widespread use, so sometimes you'll have to write your own packages. Dont worry to much though, the syntax grows on you :)
- sigzero 11y ago
  Yup, I whip up little one off utilities all the time with Tcl/Tk.
josteink 11y ago
Seems like an article ripe for pull-requests. I've already sent one on a minor formatting issue, but about one third into that article, the formatting goes permanently haywire. Weird how no one has noticed until now?
- Retr0spectrum 11y ago
  It looks like the syntax highlighter treated a * as the end of a comment, causing a " in the comment to be treated as the start of a string. That causes everything that isn't a string to be highlighted as one, and vice versa.
Johnny_Brahms 11y ago
I haven't scrolled through more than a third and suddenly I have this strange feeling of wanting to write an IRC bot. Jokes aside, TCL was for a long time my goto language for anything quick and dirty. As a result, I don't mind TCL at all. I still use Tk quite often. It might not look pretty, but it works and more crossplatform than other ui toolkits.
- kingmanaz 11y ago
  Tk has come a long way since the 8.5 release. Tk now looks native. See http://www.tkdocs.com/tutorial/index.html http://www.tkdocs.com/tutorial/index.html for an excellent tutorial.
tempodox 11y ago
Before I say more: The “Tk” part of Tcl/Tk is the one redeeming quality about Tcl. Tk gives you awesome bang-for-the-buck when it comes to building a UI. That said, Tcl is the worst parody of a programming language since the invention of BASIC and Brainfuck. All you need to know about it is two words: Stay away.
- RHSeeger 11y ago
  Personally, I find Tcl to be a fantastic language. It's extremely dynamic and powerful, making it very easy to accomplish a number of things that can be very difficult in other languages.
- gecko 11y ago
  I think you're being overdramatic, but since you didn't explain why you think Tcl is "the worst parody of a language since BASIC and Brainfuck", I can't really evaluate that. I can name lots of things about Tcl that are actually very pleasant, including the robust libraries, the homoiconic syntax, the ease of extending the language, the quickness that newbies can pick it up, and the performance (which is roughly on par with CPython, Perl and the like). What things have you hit that resulted in such an amazingly strong negative response?
  - tempodox 11y ago
    The fact that there are no data types but only strings. The necessity to navigate dynamic scoping with `upvar` & siblings. The load of having to simulate locality of reference with fancy array indexes. It may be nice for simple string-crunching scripts but a complex application is living hell. You wouldn't use /bin/sh for that, either.
    - tpoindex 11y ago
      Sounds like you haven't used Tcl since the early 1990's, you may want to check your facts. Tcl has had boolean, integer, floating point, list, dictionary, and other data types besides strings since 1997. The fact that Tcl will convert all of these values into strings when asked is immensely useful. Likewise, Tcl has had object oriented extensions since the early 1990's, and as of the last few years has OO built into the core, so you can easily build your data structures to suit.
amelius 11y ago
I was hoping for a listbox with options for X and a slider controlling the value for Y :)
- sigzero 11y ago
  That's Tk. ;)
robertskmiles 11y ago
I've just started at a place that uses a lot of Tcl for embedded scripting and customisation, and I've never used it before so this was very handy. That said, the document needs work - the syntax highlighting got very confused at some point, and a bunch of the lines are much longer than the width of the document, and don't wrap. Tcl looks like a nice little language that makes it really easy to write really horrible code. Probably with some discipline you could keep it tidy and comprehensible though.
bitwize 11y ago
Tk is great but Tcl itself... it's interesting but the difficulty in creating real data structures (as opposed to just strings) makes me start reaching for Scheme again...
- deleted 11y ago
  [deleted]
- srean 11y ago
  Tcl was never meant for that, the Ousterhout way would be to extend Tcl with the data structure written in C. Now Lua has knocked Tcl crown of "designed from scratch with embedding in mind" but at that time Tcl was indeed quite unique and one of the easiest to embed. This in a backhanded way inspired Guile: scheme intended to be embedded and/or extended. Talking about Guile, lots of fun things happening there lately. wiki.tcl.tk is a lot of fun too.
  - gioele 11y ago
    > at that time Tcl was indeed quite unique and one of the easiest to embed Could you please explain why some languages are better at being "embedded and/or extended"? Why would Guile be simpler to embed than Ruby?
    - bch 11y ago
      The Tcl shell itself (tclsh, which is many people's only interface with Tcl) is just a REPL that uses libtcl. The Tcl library is written in C, and built to be easy-to-use and powerful. Tcl also has an incredibly stable API/ABI which allows for a "stubs mechanism"[0] which is quite a nice, powerful facility that allows for seamless fixes to your Tcl-dependant work. [0] http://www.tcl.tk/doc/howto/stubs.html http://www.tcl.tk/doc/howto/stubs.html
      - srean 11y ago
        Great points. Something I feel that Tcl really got right and Python did not is handling concurrency. The Tcl way is to run the different interpreters in different threads and communicate between them by message passing but without the need for serialization - deserialization. They had this from the very beginning.

Tcl is awesome.

tonyjstark 11y ago
can you elaborate? I always wonder if I should learn it, how it would make me think in new ways and how I would use it. Tcl looks strange and that makes it very interesting for me so how do you use it and why do you use Tcl for it?
- meeper16 11y ago
  I do a lot of text mining and it's one of the most efficient languages I've used over the years for doing things like this.
  - a8da6b0c91d 11y ago
    That's an unusual assertion. Perl has much better facilities for working with unicode, and many other advanced facilities for parsing and so forth.
    - bch 11y ago
      > Perl has much better facilities for working with unicode Which facilities are those ? > many other advanced facilities for parsing Be curious to hear what those are, but note that Tcl is hilariously simple to extend and build up custom constructs to suit ones needs.
      - eviltwinskippy 11y ago
        Not to mention that Tcl has Unicode in the core, has had Unicode in the core for at least 8 years, and the long and short is that EVERY string operation is Unicode aware. You can have unicode procedure names, if that was your fancy.
        bch 11y ago
        ...right, which is why I was wondering where Perl's support is superior. Tcl's support isn't perfect nor complete, but it's still pretty impressive.
    - wrenky 11y ago
      I would like to see what advanced facilities perl has for text parsing that TCL doesn't!
      - kbenson 11y ago
        Me too, but I suspect it might take someone of tchrist's level with experience in both languages to give a good answer. I would be interested in how TCL handles the issues tchirst has to deal with outlined in his famous SO post[1]. Note: If you read that post and think, "Wow, Perl requires a lot of setup for unicode and TCP doesn't require nearly as much" without understanding the specifics of why each step is there, and how TCL handles the same issue, you are likely underthinking the issue. 1: http://stackoverflow.com/questions/6162484/why-does-modern-perl-avoid-utf-8-by-default http://stackoverflow.com/questions/6162484/why-does-modern-p...
- _pmf_ 11y ago
  It offers the syntactic freedom of Lisp/Scheme without the parentheses.
  - _ph_ 11y ago
    The top level of parenthesis-es is left out, the other levels replaced by brackets :). But joking aside, I greatly enjoy both Lisp and Tcl as languages.
    - a8da6b0c91d 11y ago
      A huge, seriously annoying problem with TCL is lack of deterministic cleanup for resources. If you don't manually close a filehandle, for example, it will leak. Doing this sort of bookkeeping in 2015 is infuriating.
      - sebcat 11y ago
        proc with {file as name block} { uplevel 1 [list set $name $file] uplevel 1 [list eval $block] uplevel 1 [list close $file] } with [open foo.txt w] as file { puts $file "Hello, World!" } I'm sure it's possible to do it in a cleaner way without [set], but my Tcl is a bit rusty.
        a8da6b0c91d 11y ago
        Still leaks on an exception. That's also an annoying construct to be forced to use.
        nilkn 11y ago
        You could easily wrap the middle uplevel in a catch block to handle exceptions, and this sort of "with" construct is pretty common in a lot of very popular languages today. While it would be nice if this were baked into the language, it's pretty astonishing how extensible Tcl is without even having to touch the realm of C extensions.
- reacweb 11y ago
  TCL/TK is incredibly powerful to put a GUI in front of a bunch of scripts. You can easily bind a regexp in a log file to events that update widgets. I wish I had learned it 20 years ago.
  - ash 11y ago
    Could you give an example of that?
    - mdaniel 11y ago
      If by "that" you mean an example of a GUI on top of scripts, the `git gui` and `gitk` that ship with git are in Tcl/Tk and shell out to the git commands that do the work As others have mentioned, they are very, very not "native UI" friendly - OSX is an especially bad instance - but they do run on all of Git's platforms without a 20MB runtime to go along with them. If Tk's widgets were just a little less harsh, those two would absolutely be my go-to graphical git clients.
- stevekemp 11y ago
  This is a great introduction, by antirez of redis-fame. http://antirez.com/articoli/tclmisunderstood.html http://antirez.com/articoli/tclmisunderstood.html
- msravi 11y ago
  Tcl is also the de-facto default language for almost all VLSI tools
- wainstead 11y ago
  This post occasionally makes the rounds and is an enlightening read: http://antirez.com/articoli/tclmisunderstood.html http://antirez.com/articoli/tclmisunderstood.html
- wrenky 11y ago
  We use TCL for almost everything that isn't C/C++, its insanely flexible. You can completely redefine the syntax if you want as there are NO keywords. Meta programming is easy, as all TCL commands follow the same format- Its only con is the lack of widespread use, so sometimes you'll have to write your own packages. Dont worry to much though, the syntax grows on you :)
sigzero 11y ago
Yup, I whip up little one off utilities all the time with Tcl/Tk.

Seems like an article ripe for pull-requests. I've already sent one on a minor formatting issue, but about one third into that article, the formatting goes permanently haywire. Weird how no one has noticed until now?

Retr0spectrum 11y ago
It looks like the syntax highlighter treated a * as the end of a comment, causing a " in the comment to be treated as the start of a string. That causes everything that isn't a string to be highlighted as one, and vice versa.

Johnny_Brahms 11y ago

I haven't scrolled through more than a third and suddenly I have this strange feeling of wanting to write an IRC bot. Jokes aside, TCL was for a long time my goto language for anything quick and dirty. As a result, I don't mind TCL at all. I still use Tk quite often. It might not look pretty, but it works and more crossplatform than other ui toolkits.

kingmanaz 11y ago
Tk has come a long way since the 8.5 release. Tk now looks native. See http://www.tkdocs.com/tutorial/index.html http://www.tkdocs.com/tutorial/index.html for an excellent tutorial.

tempodox 11y ago

Before I say more: The “Tk” part of Tcl/Tk is the one redeeming quality about Tcl. Tk gives you awesome bang-for-the-buck when it comes to building a UI. That said, Tcl is the worst parody of a programming language since the invention of BASIC and Brainfuck. All you need to know about it is two words: Stay away.

RHSeeger 11y ago
Personally, I find Tcl to be a fantastic language. It's extremely dynamic and powerful, making it very easy to accomplish a number of things that can be very difficult in other languages.
gecko 11y ago
I think you're being overdramatic, but since you didn't explain why you think Tcl is "the worst parody of a language since BASIC and Brainfuck", I can't really evaluate that. I can name lots of things about Tcl that are actually very pleasant, including the robust libraries, the homoiconic syntax, the ease of extending the language, the quickness that newbies can pick it up, and the performance (which is roughly on par with CPython, Perl and the like). What things have you hit that resulted in such an amazingly strong negative response?
- tempodox 11y ago
  The fact that there are no data types but only strings. The necessity to navigate dynamic scoping with `upvar` & siblings. The load of having to simulate locality of reference with fancy array indexes. It may be nice for simple string-crunching scripts but a complex application is living hell. You wouldn't use /bin/sh for that, either.
  - tpoindex 11y ago
    Sounds like you haven't used Tcl since the early 1990's, you may want to check your facts. Tcl has had boolean, integer, floating point, list, dictionary, and other data types besides strings since 1997. The fact that Tcl will convert all of these values into strings when asked is immensely useful. Likewise, Tcl has had object oriented extensions since the early 1990's, and as of the last few years has OO built into the core, so you can easily build your data structures to suit.

amelius 11y ago

I was hoping for a listbox with options for X and a slider controlling the value for Y :)

sigzero 11y ago
That's Tk. ;)

robertskmiles 11y ago

I've just started at a place that uses a lot of Tcl for embedded scripting and customisation, and I've never used it before so this was very handy. That said, the document needs work - the syntax highlighting got very confused at some point, and a bunch of the lines are much longer than the width of the document, and don't wrap. Tcl looks like a nice little language that makes it really easy to write really horrible code. Probably with some discipline you could keep it tidy and comprehensible though.

bitwize 11y ago

Tk is great but Tcl itself... it's interesting but the difficulty in creating real data structures (as opposed to just strings) makes me start reaching for Scheme again...

deleted 11y ago
[deleted]
srean 11y ago
Tcl was never meant for that, the Ousterhout way would be to extend Tcl with the data structure written in C. Now Lua has knocked Tcl crown of "designed from scratch with embedding in mind" but at that time Tcl was indeed quite unique and one of the easiest to embed. This in a backhanded way inspired Guile: scheme intended to be embedded and/or extended. Talking about Guile, lots of fun things happening there lately. wiki.tcl.tk is a lot of fun too.
- gioele 11y ago
  > at that time Tcl was indeed quite unique and one of the easiest to embed Could you please explain why some languages are better at being "embedded and/or extended"? Why would Guile be simpler to embed than Ruby?
  - bch 11y ago
    The Tcl shell itself (tclsh, which is many people's only interface with Tcl) is just a REPL that uses libtcl. The Tcl library is written in C, and built to be easy-to-use and powerful. Tcl also has an incredibly stable API/ABI which allows for a "stubs mechanism"[0] which is quite a nice, powerful facility that allows for seamless fixes to your Tcl-dependant work. [0] http://www.tcl.tk/doc/howto/stubs.html http://www.tcl.tk/doc/howto/stubs.html
    - srean 11y ago
      Great points. Something I feel that Tcl really got right and Python did not is handling concurrency. The Tcl way is to run the different interpreters in different threads and communicate between them by message passing but without the need for serialization - deserialization. They had this from the very beginning.