4 ms·

Yeah the level of dynamicness (dynamism?) you can get in tcl is unparalleled as far as I can see. Having no types or syntax and access to the entire runtime at

by mroll 10y ago

Yeah the level of dynamicness (dynamism?) you can get in tcl is unparalleled as far as I can see. Having no types or syntax and access to the entire runtime at any point in the program opens up all kinds of crazy doors. But you're right, that slows it down. But you might be interested to know there is currently an effort to get Tcl to compile to native/near-native code. Here is a paper on the new techniques being developed and a link to a talk given by one of the lead tcl core team members. http://www.tcl-lang.org/community/tcl2015/assets/talk14/TheTclQuadcodeCompiler.pdf http://www.tcl-lang.org/community/tcl2015/assets/talk14/TheT... https://www.youtube.com/watch?v=RcrqmZV88PY&t=38s https://www.youtube.com/watch?v=RcrqmZV88PY&t=38s

qwertyuiop924 10y ago
Picolisp can match it in dynamism. Seriously, Picolisp is absolutely insane.
- mroll 10y ago
  I just read a bit of documentation from the Picolisp page. It looks really cool, but can it reach arbitrarily far up the call stack? That's the quality of tcl that I don't see other places. The capabilities of 'upvar' and 'uplevel'. [Edit] I should say "one of the qualities." The other important one is that Tcl has no types. Even all the lisps I know have types.
  - vram22 10y ago
    >The other important one is that Tcl has no types. Is it that it has no types or that everything is a string? asking, not stating.
    - mroll 10y ago
      Yes, everything is a string. But you can pass data around anywhere you like without worrying about coercing. A command will receive its data in string representation and treat it however it likes. So when you go to do math with the 'expr' command, 'expr' will treat its arguments as numbers. set x 5 expr { $x + 3 } 'expr' receives x as the string 5 but knows to treat it as an int. I'm not sure that's a great explanation. Maybe a decent summary of the concept of 'no types' is "the language does not presume to tell you how you can or cannot use your data."
      - vram22 10y ago
        Thanks. Yes, I get it. I had read part of the Ousterhout book. And also Don Libes' Expect book uses Tcl, since Expect is written in it. Had read a lot of that too. Both very good ones. Didn't get to use Tcl in projects though. I'd read some years ago that Tcl was used heavily in the electronics / EDA industry.
  - qwertyuiop924 10y ago
    The functions you're looking for are called `up` and `run` in picolisp. And before you ask, yes, picolisp has list interpolation (or quasiquoting, in lisp parlance), so you can control which parts of a certain chunk of code will be run when, and in which contexts. It also includes the `macro` fexpr, which makes interpolation more convenient.
    - mroll 10y ago
      Wow, very interesting. Thanks for pointing out picolisp!
goatlover 10y ago
I believe IO lets you do the same. Everything is a prototype with slots, communicating via messages. I guess Self was the same way. Self & Smalltalk also give you access to the entire runtime.
- qwertyuiop924 10y ago
  But TCL actually goes beyond that. Most languages of this sort, like Smalltalk, Lisp, and especially slower, more liberal implementations like PicoLisp, allow for compile-time and/or runtime AST transformation, and other sorts of metaprogramming. in TCL, everything is a string. Or at least, everything behaves like a string in the proper context. When you pass code blocks into a command (like if, or while, or whatever), you're not passing code objects: you're passing unevaled strings. This is why expr works in TCL: there's nothing special about expr, it's just actually implementing a DSL (sort of) rather than evaling your code straight up. The practical upshot of this is that unlike smalltalk (I think: Can an ST user actually answer this?), and to a greater degree than LISP and FORTH (;immediate and readtables are a lot more painful to wrangle), you can not only modify the semantics of the language: you can modify the syntax.
  - pjmlp 10y ago
    Smalltalk just like Lisp has very little syntax, almost everything is built on messages, including data type creation, conditionals and loops, among other things. Also you can at any time just completely replace one object by other via the becomes: message. There are also some cool tricks when metaclasses are used, many of each one can see in Python as well.
    - qwertyuiop924 10y ago
      However, IIRC, unlike Lisp, ST doesn't have any AST transformation or parsing hooks (macros and readtables, in Lisp parlance), so while ST has a lot of the semantic extension capabilities of Lisp (indeed, it's more semantically extensible than some of the less Object Oriented Lisps), it lacks the syntactic capabilities for extension. However, you know ST better than me. Am I right?

by mroll 10y ago

qwertyuiop924 10y ago

Picolisp can match it in dynamism. Seriously, Picolisp is absolutely insane.

mroll 10y ago
I just read a bit of documentation from the Picolisp page. It looks really cool, but can it reach arbitrarily far up the call stack? That's the quality of tcl that I don't see other places. The capabilities of 'upvar' and 'uplevel'. [Edit] I should say "one of the qualities." The other important one is that Tcl has no types. Even all the lisps I know have types.
- vram22 10y ago
  >The other important one is that Tcl has no types. Is it that it has no types or that everything is a string? asking, not stating.
  - mroll 10y ago
    Yes, everything is a string. But you can pass data around anywhere you like without worrying about coercing. A command will receive its data in string representation and treat it however it likes. So when you go to do math with the 'expr' command, 'expr' will treat its arguments as numbers. set x 5 expr { $x + 3 } 'expr' receives x as the string 5 but knows to treat it as an int. I'm not sure that's a great explanation. Maybe a decent summary of the concept of 'no types' is "the language does not presume to tell you how you can or cannot use your data."
    - vram22 10y ago
      Thanks. Yes, I get it. I had read part of the Ousterhout book. And also Don Libes' Expect book uses Tcl, since Expect is written in it. Had read a lot of that too. Both very good ones. Didn't get to use Tcl in projects though. I'd read some years ago that Tcl was used heavily in the electronics / EDA industry.
- qwertyuiop924 10y ago
  The functions you're looking for are called `up` and `run` in picolisp. And before you ask, yes, picolisp has list interpolation (or quasiquoting, in lisp parlance), so you can control which parts of a certain chunk of code will be run when, and in which contexts. It also includes the `macro` fexpr, which makes interpolation more convenient.
  - mroll 10y ago
    Wow, very interesting. Thanks for pointing out picolisp!

goatlover 10y ago

I believe IO lets you do the same. Everything is a prototype with slots, communicating via messages. I guess Self was the same way. Self & Smalltalk also give you access to the entire runtime.

qwertyuiop924 10y ago
But TCL actually goes beyond that. Most languages of this sort, like Smalltalk, Lisp, and especially slower, more liberal implementations like PicoLisp, allow for compile-time and/or runtime AST transformation, and other sorts of metaprogramming. in TCL, everything is a string. Or at least, everything behaves like a string in the proper context. When you pass code blocks into a command (like if, or while, or whatever), you're not passing code objects: you're passing unevaled strings. This is why expr works in TCL: there's nothing special about expr, it's just actually implementing a DSL (sort of) rather than evaling your code straight up. The practical upshot of this is that unlike smalltalk (I think: Can an ST user actually answer this?), and to a greater degree than LISP and FORTH (;immediate and readtables are a lot more painful to wrangle), you can not only modify the semantics of the language: you can modify the syntax.
- pjmlp 10y ago
  Smalltalk just like Lisp has very little syntax, almost everything is built on messages, including data type creation, conditionals and loops, among other things. Also you can at any time just completely replace one object by other via the becomes: message. There are also some cool tricks when metaclasses are used, many of each one can see in Python as well.
  - qwertyuiop924 10y ago
    However, IIRC, unlike Lisp, ST doesn't have any AST transformation or parsing hooks (macros and readtables, in Lisp parlance), so while ST has a lot of the semantic extension capabilities of Lisp (indeed, it's more semantically extensible than some of the less Object Oriented Lisps), it lacks the syntactic capabilities for extension. However, you know ST better than me. Am I right?