I gave the reason why I against using the following syntax

  [] funcname

to lift an overload set / operators into a lambda expression:
the captures are never used.  Moreover, they may end up
being misleading.  Consider the member access support in
p01192r2 prefixed with []:

  [] obj.data

So this lambda captures obj or not?

So I try to go back to the origin of the problem we are solving:
we have various kinds of things which are close to callable,
just not first-class.  And the transformation we are doing are
merely from

  f

to

  \x -> f(x)

In lambda calculus, we call this transformation Eta-expansion
(=CE=B7-reduction for the reserve process, and =CE=B7-conversion for
either -- adding or dropping an abstraction).

Scala is a language that I know for using the term Eta-expansion
in its language spec, because they face a similar problem --
methods are not functions.

And my suggestion for C++ is very simple:

  etaexpr(funcname)
  etaexpr(std::iota)
  etaexpr(<)

etc.  A new keyword, etaexpr, seems never seen according to
google and github, reads "Eta (wrapped/expanded) expression",
and means "to wrap a lexical lookup / operator / member access
into a lambda".

--=20
Zhihao Yuan, ID lichray
The best way to predict the future is to invent it.
___________________________________________________
4BSD -- http://blog.miator.net/

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