It's a combination of cumbersome syntax and the vendor's poor API design and execution environment.For a syntax example, compare python to Tcl. In python, there's a compact array lookup operator, and dictionaries allow string keys:
mydata["channel"][2]
Tcl, however, requires a function call to access an array index, resulting in nested function calls with magic numbers for the simplest expressions: lindex [lindex $mydata 35] 2 # Tcl
Then there isn't any static type checking so you have to run code to see if it would work; the shape of a return may surprise you. Connecting to hardware may be your only opportunity to exercise certain code paths.So for any non trivial task, Tcl becomes effectively write-only.
Some tools allow you to export Tcl scripts that automate tasks like project creation to help you avoid tracking intermediate objects in source control, but because the Tcl cwd path can change throughout a script, they export every source path as a hard coded absolute path, including whatever developer's home directory it might be residing in. This is not suitable for source control (because it would preclude building on any other machine) so then you have to post process these scripts before tracking them. But since it's Tcl there aren't good scriptable tools for programmatic Tcl AST manipulation, so you have to modify these files with some sort of a state machine, looking for various sentinels to trigger the various string replace behaviors you need. It's not all Tcl's fault, but if a vendor is only using Tcl for automation and you need automation, you have a battle ahead of you.
Outside the language, you'll often find that your runtime tool locks the UI thread to run your scripts, so long running operations are impossible to pause or cancel. And I've never seen a vendor expose adequate objects to allow full control, so often, the critical actions you hoped to automate are only possible through the GUI.
In the 90s, an integrated Tcl interpreter was a good sign that your vendor cared about developers. Today it's more a sign of neglect.
2/16/2026
at
8:40:02 PM
> Tcl, however, requires a function call to access an array index, resulting in nested function calls with magic numbers for the simplest expressions:I do understand how that one can be frustrating to a newbie, but I can't fault that implementation choice when thinking about Tcl as a "Lisp but it's strings".
> Then there isn't any static type checking so you have to run code to see if it would work; the shape of a return may surprise you. Connecting to hardware may be your only opportunity to exercise certain code paths.
This, though, yeah. I feel this in my whole body. I haven't checked out Tcl 9.0 to see how it's changed, but Tcl 8.6's abbreviated compilation phase definitely doesn't leave any room for type much type inference ahead-of-time.
> sentinels
Tangential, but man I wish Tcl had `gensym` out of the box. That alone was enough to start my own programming language over a decade ago.
Everything else, I largely agree with. Short of a hard fork or the Tcl team splitting their time between maintaining for the sake of EDA vendors, and trying different approaches, I don't see much changing.
I really appreciate the time you took to share your experiences here.
by xantronix