"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It's worth noting that Stallman's criticism linked above is more than three decades out of date.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.
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."