''[CMcC] 8/7/7'' Tcl contains some semantic equivalences.  ''~~'' can be read as ''approximates''.  Add more if you find them.  The hunt is on.

----
   * '''$varname ~~ [[[set] varname]]'''

Example:
        set abc "123"
        set xyz $abc
or
        set xyz [set abc]

----
   * '''[[script]] ~~ [[[eval] {script}]]'''

Example:

[[replace with example]]

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   * '''"string" ~~ [[[subst] string]]'''

Example:

Using "string" can result in quoting hell for some strings while using subst is more verbose but "cleaner".

[[replace with example]]

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   * '''"$list1 $list2 ..." ~~ [[[concat] $list1 $list2 ...]]'''

Example:
        set colors {taupe puce heliotrope}
        set countries {Djibouti Brazil Azerbaijan}
        set var "$colors $countries"
        set var [concat $colors $countries]

----
   * '''"a b c ..." ~~ [[[list] a b c ...]]'''
   * '''{a b c ...} ~~ [[[list] a b c ...]]'''

Example:
        set var "1 2 3"
        set var {1 2 3}
        set var [list 1 2 3]

----
   * '''[[[global] varname]] ~~ ::varname'''
   * '''[[[upvar] #0 varname varname]] ~~ ::varname'''

Example:
        set abc $::env(HOME)
or
        global env
        upvar #0 env env2
        set abc $env(HOME)
        set abc2 $env2(HOME)

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''[escargo] 7/7/7 -'' Are you looking for examples how these are '''not''' equivalent?  [CMcC] I changed it to 'approximates.'

For example, I seem to recall that [[[eval]]] does a round of substitution before evaluating
its input.  (Logically, it would seem to be necessary for '''[[]] !~ [[[eval]]]''', otherwise
eval is just taking up space.)

And [subst] takes arguments that allow limitations on the substitutions.

[LV] I think what is being sought are cases where ''there is more than one way to do it'', as the [Perl] community says. This could be cases of Tcl syntactical ''sugar'' (notational shortcut approximates).

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