Bash and Powershell are shells, they are command languages, and not programming languages like C#. That distinction, while in many ways subtle with tons of overlap, is the primary factor in shell syntax being crappy as a "language" -- it's because command evaluation is (necessarily) prioritized over language design. There is a good reason that no shells exist that have a "better designed language." As well as good reasons that no well designed programming language makes a good shell. They solve different problems, and I don't think C# would make a good command shell without significant syntax compromises.
> There is a good reason that no shells exist that have a "better designed language." As well as good reasons that no well designed programming language makes a good shell.
Hmm good question! It's been a very long time since I used tcl/tk, but I just gave myself a 2 minute refresher and browsed the docs. I would say Tcl is a programming language, not a system shell. The tcl tutorial concurs, calls tcl specifically a 'dynamic programming language', and compares tcl to python.
I'm definitely using 'shell' and 'command' in a narrow sense. I meant to add contrast between PowerShell and C#, by calling one a command shell and the other a programming language. But both words have been used with much broader meanings. So I'll try to be a little more careful and say that what I'm really talking about is a system shell and system commands, where a system command means direct access to executable files on the system, and system shell means an interpreter that provides system commands.
Even though Tcl stands for 'command language', it's not talking about system commands using the same distinction I made above. Tcl's use of "command" is referring to programmer-defined functions & API, and it is not referring to system commands.
Tclsh is a shell, but I wouldn't call that a system shell like PowerShell or bash. It is an interactive tcl interpreter, but not really a system shell. Tclsh isn't something sysadmins would typically use, right?
Perhaps the defining characteristic of a system shell (as opposed to a programming language) is system commands; running executable files on the system can be done by typing the bare name of the file, without any other syntax in the way. That is true in powershell and bash, and not true in C#, tcl, python, etc. To run a system command in tcl, you have to use 'exec' or 'open', you have to use 'glob' to get file completion, and there's required programming language syntax frequently involved in passing arguments. In tcl you have to use $env(var) or $::env(var) to get an environment variable rather than $var. Those are the kinds of things that shells provide with little or no syntax, and exactly the kind of stuff that begins to compromise language syntax and language design in favor of promoting system commands to first class status.
BTW, you got me curious about tcl again. I never used it enough to get a sense of what it's best used for. What kinds of things would you use tcl for yourself? Do you like to use it for system shell tasks instead of bash? (I know there are certainly legit reasons to do that.) What kinds of programs would you start in tcl?
