We need closures

[Mildred Ki'Lya]

Not really my saying (even if it could or was):

http://notes-on-haskell.blogspot.com/2008/09/closures-are-coming.html

Short summary, closures are being implemented in C (LLVM+clang,
initiated by Apple for ObjectiveC)

Basically, closures are functions that can be passed as values and that
reference variables from outside of the function. The tricky part of
implementing them is when the function is called at a moment where the
variables it uses are no longer then.

Imagine the Lisaac code:

  - return_a_closure initial_value:INTEGER :{;INTEGER} <-
  ( + count :INTEGER;
    count := initial_value - 1;
    {
      count := count + 1;
      count
    }
  );

  - uses_a_closure <-
  ( + closure :{;INTEGER};
    closure := return_a_closure 1;
    closure.value.println;  // 1
    closure.value.println;  // 2
    closure.value.println;  // 3
    closure.value.println;  // 4
  );

Unfortunately, such code is likely to raise an error, the compiler
saying that the BLOCK is used outside the variable 'count' scope.

This is just to illustrate the concept of closure, not its usefulness.

Mildred
-- 
Mildred Ki'Lya
╭───────── ｍｉｌｄｒｅｄ５９３＠ｏｎｌｉｎｅ．ｆｒ ──────────
│ Jabber, GoogleTalk: <mildred at jabber.fr>
│ Site: <http://ki.lya.online.fr>              GPG ID: 9A7D 2E2B
│ Fingerprint: 197C A7E6 645B 4299 6D37 684B 6F9D A8D6 9A7D 2E2B