I can't speak to what most people expect from lambdas; I force myself use Tcl's [apply] occasionally just to try slightly different paradigms, so I appreciate your commentary.
One thing to note though, your final [inc 1] has nothing to do w/ $inc. In the interactive REPL (which I'm assuming you used), Tcl will (by default) essentially autocomplete commands if it can, and [inc] completed to [incr], which is "increment". [incr] adds (by default) 1 to the named variable and returns its result. In this case, the variable name happens to be "1", later accessible via "$1", or [set 1], for example.
[edit: I erroneously initially described the "1" in [incr 1] as the integer constant 1; @groovy2shoes reply below reflects my original error. This does go to show another neat feature of Tcl: no keywords.]
I didn't know that tclsh autocompletes commands; that's pretty neat. In this case, it looks like [incr 1] is incrementing a variable called 1, and appears to start from zero if the variable isn't initialized.
I find Tcl's command model interesting because it leads to a very tiny semantics. A few years ago I spent a lot of time thinking about how it could be extended to have lambdas, and I couldn't come up with a way that wouldn't break the command model in some way or another. They aren't something Tcl needs to have, I just thought it'd be convenient. (Tcl's evaluation model allows you to simulate higher-order procs, which, along with `apply`, covers many use cases of lambda).
Ya -- interactive tclsh has a few creature-features. The autocomplete we're discussing, automatic fall-through to exec as if via sh(1), command history, history editing, and perhaps more I'm forgetting.
kamloops$ tclsh8.6
% info commands up*
update uplevel upvar
% uptime
7:17PM up 1 hr, 7 users, load averages: 0.06, 0.12, 0.17
% ls fu
ls: fu: No such file or directory
child process exited abnormally
% ls -ld fu
ls: fu: No such file or directory
child process exited abnormally
% ^fu^foo
ls -ld foo
-rwxr-xr-x 1 joe users 7300 Mar 23 2011 foo
% history
1 info commands up*
2 uptime
3 ls fu
4 ls -ld fu
5 ls -ld foo
6 history
% !2
uptime
7:20PM up 1:03, 7 users, load averages: 0.13, 0.12, 0.16
@groovy2shoes (and anybody else who's interested in modern (or historic, for that matter) Tcl), you should drop by #tcl on irc.freenode.net. We'd love to have you visit.
To my point of no keywords, and touching on the interesting model @groovy2shoes is talking about here[1]:
$ tclsh
% set a set
set
% puts $a
set
% $a b 9
9
% set b
9
% set set set
set
% $set set
set
% rename set foo
% foo set
set
% foo a
set
% foo a 9
9
% puts $a
9
%
One thing to note though, your final [inc 1] has nothing to do w/ $inc. In the interactive REPL (which I'm assuming you used), Tcl will (by default) essentially autocomplete commands if it can, and [inc] completed to [incr], which is "increment". [incr] adds (by default) 1 to the named variable and returns its result. In this case, the variable name happens to be "1", later accessible via "$1", or [set 1], for example.
[edit: I erroneously initially described the "1" in [incr 1] as the integer constant 1; @groovy2shoes reply below reflects my original error. This does go to show another neat feature of Tcl: no keywords.]