Re: a typeof command for debugging?

shows you the last type that was used on that object (besides string):
 (chris) 50 % set a [expr {23*5}]
115
(chris) 51 % tcl::unsupported::representation $a
value is a int with a refcount of 4, object pointer at 0x55d6b8f8b320, internal representation 0x73:(nil), string representation "115"
            Christian

PS: Since you are new to Tcl, please have a look at the following:
(chris) 52 % set a {1 2 3 4}
1 2 3 4
(chris) 53 % tcl::unsupported::representation $a
value is a pure string with a refcount of 5, object pointer at 0x55d6b8f8ac90, string representation "1 2 3 4"
(chris) 54 % lindex $a 2
3
(chris) 55 % tcl::unsupported::representation $a
value is a list with a refcount of 4, object pointer at 0x55d6b8f8ac90, internal representation 0x55d6b8c06cf0:(nil), string representation "1 2 3 4"
(chris) 56 %
Also, the {} do not make the list, they are a quoting mechanism. You will get an identical result if you use "":
(chris) 61 % tcl::unsupported::representation $b
value is a pure string with a refcount of 5, object pointer at 0x55d6b8f85860, string representation "1 2 3 4 5 6"
(chris) 62 % lindex $b 2
3
(chris) 63 % tcl::unsupported::representation $b
value is a list with a refcount of 4, object pointer at 0x55d6b8f85860, internal representation 0x55d6b8f14b40:(nil), string representation "1 2 3 4 5 6"
(chris) 64 %
And, there is "constant sharing". After you ran the previous examples, try with another surprise:
(chris) 64 % set c "1 2 3 4"
1 2 3 4
(chris) 65 % tcl::unsupported::representation $c
value is a list with a refcount of 9, object pointer at 0x55d6b8f8ac90, internal representation 0x55d6b8c06cf0:(nil), string representation "1 2 3 4"
(chris) 66 %
Christian