if-let for Dylan

readme.md

Based on Dylan's anaphora

if-let-with-parens.dylan

Module: iflet
Synopsis: 
Author: 
Copyright: 

define macro if-let
  { if-let (?:name = ?:expression) ?b1:body else ?b2:body end }
    => { let ?name = ?expression;
        if(?name) ?b1 else ?b2 end }
  { if-let (?:name = ?:expression) ?:body end }
    => { let ?name = ?expression;
        if(?name) ?body end }
end macro if-let;


define function main
    (name :: <string>, arguments :: <vector>)
  if-let (pos = position(arguments, "cat", test: \=))
    format-out("You have a cat at position %d\n", pos);
  else
    format-out("You don't have any cats\n");
  end;
  exit-application(0);
end function main;

main(application-name(), application-arguments());

iflet.dylan

Module: iflet
Synopsis: 
Author: 
Copyright: 

define macro if-let
  { if-let ?:name = ?:expression ?b1:body else ?b2:body end }
    => { let ?name = ?expression;
        if(?name) ?b1 else ?b2 end }
  { if-let ?:name = ?:expression ?:body end }
    => { let ?name = ?expression;
        if(?name) ?body end }
end macro if-let;


define function main
    (name :: <string>, arguments :: <vector>)
  if-let pos = position(arguments, "cat", test: \=)
    format-out("You have a cat at position %d\n", pos);
  else
    format-out("You don't have any cats\n");
  end;
  exit-application(0);
end function main;

main(application-name(), application-arguments());