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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

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.

remram 2y ago
That is absolutely not how Python works. Python values are typed.
- apgwoz 2y ago
  > "a dynamically typed language is a statically typed language with only one static type." — Bob Harper
  - remram 2y ago
    Yes but we are not talking about static types...
    - apgwoz 2y ago
      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.
      - layer8 2y ago
        The runtime values have tags that denote their runtime type. They are not of a single type. You are talking about static types.
        apgwoz 2y ago
        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.
      - remram 2y ago
        What you said above is correct but is not related to what was being discussed before.
        apgwoz 2y ago
        How is it not related? 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…
        bombarolo 2y ago
        I can see a difference that I can understand the Python’s error message, the Tcl’s one not so much.
        apgwoz 2y ago
        Error message usefulness is not a strict requirement of type systems.
- eadmund 2y ago
  > Python values are typed. So are Tcl values.
7thaccount 2y ago
Does it still do this? I thought they changed this many years ago?
- smj-edison 2y 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.

remram 2y ago

That is absolutely not how Python works. Python values are typed.

apgwoz 2y ago
> "a dynamically typed language is a statically typed language with only one static type." — Bob Harper
- remram 2y ago
  Yes but we are not talking about static types...
  - apgwoz 2y ago
    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.
    - layer8 2y ago
      The runtime values have tags that denote their runtime type. They are not of a single type. You are talking about static types.
      - apgwoz 2y ago
        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.
    - remram 2y ago
      What you said above is correct but is not related to what was being discussed before.
      - apgwoz 2y ago
        How is it not related? 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…
        bombarolo 2y ago
        I can see a difference that I can understand the Python’s error message, the Tcl’s one not so much.
        apgwoz 2y ago
        Error message usefulness is not a strict requirement of type systems.
eadmund 2y ago
> Python values are typed. So are Tcl values.

7thaccount 2y ago

Does it still do this? I thought they changed this many years ago?

smj-edison 2y 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.