[fpc-devel] New feature discussion: LAMBDA

[Dariusz Mazur]

Michael Schnell pisze:
> Again something inspired by Delphi-Prism ?
>
> ( http://prismwiki.codegear.com/en/Lambda_Expressions )
>
>   
No at all, I don't even see this before. I thing long about this. But 
lately I see this in C++ (strange) and Lisp (beautiful)
In Prism have You:

c -> c.Name = 'Smith'

which is very strange, special syntax, and need to be translate to "method", and declaration longer 
than one line is awful,

my proposition semantically is between properties (they consist also two function), 
aspect programming and lambda

is very easy to translate to ordinal pascal( lambda invoke change to repeat-while iteration,
similarly as in generics)

has wider application:

from FPC WIKI:
procedure StringLoop(S: String);
var
  C: Char;
begin
  for C in S do
    DoSomething(C);
end; 

my prop:

procedure stringloop(s :tMyString);
begin
   {with} s.eachword do begin
      if s.currentword<>'begin' then
        writeln(s.currentword);
   end;
end;

of course I can write
      
procedure stringloop(s :tMyString);
begin
   s.firstWord;
   try
   while  s.nexword do begin
      if s.currentword<>'begin' then
        writeln(s.currentword);
   end;
   except
     s.exceptWord;
   end;  
end;

which can be equivalent

from compiler side invoke of lambda is translate to proper iteration before main compilation
from developer side: its easy to use as properties, 
fewer bugs caused forget of initialization or finalization, or use incompatible  init and step
function in iterators




-- 
  Darek