Part ... of the Feather extensions.
lambda <args> <body>
Creates a lambda command object. Apart from the lack of name the semantics of ... this command are the same as for a proc. e.g.
% set add [lambda {a b} {puts "([info level]) $a + $b = [expr {$a + $b}]"}]
<feather::lambda 0x200620b8>
% $add 1 2
(1) 1 + 2 = 3
% set add2 [curry $add 2]
<feather::curried 0x20050338>
% $add2 6
(1) 2 + 6 = 8 The Tcl 8.5 apply command provides similar functionality.