[Richard Suchenwirth] 2002-02-14 - Lambda is the name for the letter "L" in the Greek alphabet. Since Alonzo Church's "Lambda calculus", it is also the term for anonymous functions. Consider
 f(x) = x+1
is not much different from
 g(x) = x+1
except for the f/g difference, which are both arbitrary names. The common essence of the above functions, ignoring the name, is just
 (x) = x+1
or in other words, "given x, return x+1". In Tcl, this looks like
 lambda x {expr {$x+1}}
and it's easy to implement - see [Lambda in Tcl].

To have lambdas directly, one change to Tcl would be:
   * If a command name is a list of length three, with [lambda] as first element, bind its arguments to the second element of the list, and then evaluate the third element in that scope.

As long as we don't have this, a simple way is to make up a name for a [proc]:
 proc lambda {argl body} {
    set name [info level 0]
    proc $name $argl $body
    set name
 }
where the lambda definition is returned as command name.

See also [RPN again] for "half-lambdas": only the body is the value of a function, arguments are popped from the stack, the result is pushed on the stack.
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It seems like it would be pretty easy for [unknown] to do this automatically...

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