Looking at Tcsh

The shell syntax can be c, but they use a set command to establish a variable:

set var="Hello"

why not?

int var = "hello";  // And include the comments.

The problem is that command line operations are not bound to the syntax. In Default:

Default int var = "hello"; // Uses the Default key word to signify which syntax to use.

Then the command line stays in Default mode until it reaches its own exit, or fails.

Then all the shells have command line edits, move cursor left, right, delete, and  others.  I don't have these because I am using the Xchars package, not termios or Ncurses or anything else. Cursor placement, user  IO is governed by xcb messages, not terminal control sequences. Once Xchars cursor messages flow, then I can add all the command line history and line edits.

The other difference, default linux commands should be pass through Default, while Tcsh intercepts them.  In summary, the syntax engine selected controls command line, not visa versa.

The good thing about Tsch is the source code has constructions for c syntax which may be useful. But Tcsh is not going to compete with MS PowerShell any time soon.