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2 points by CatDancer 5625 days ago | link | parent

> it seems to work for me

  (mac myeach (first expr . body)  
          `(if (defined ,first)  
             (each _ ,first ,expr ,@body)
             (prn "undefined")))
ah, but now you're doing the 'defined test at run time. What you want is to be able to do the 'defined test at macro expansion time in order to affect how your macro is expanded, and that, as far as I know, Arc isn't able to do for you.


1 point by palsecam 5625 days ago | link

> now you're doing the 'defined test at run time.

Yes, but check the previous messages, I've always wanted to do so. The definition of 'myeach basically never changed.

> What you want is to be able to do the 'defined test at macro expansion time in order to affect how your macro is expanded

Not necessary (maybe yes in the current Arc because of the 'if behaviour, but between making the language works for me [change its behaviour] or works for the language [change my behaviour], you'll guess what I prefer), and no, this is too precise. What I want is 'each to be smart and have an "anonymous form". Which tricks to use to get that, I don't care. I don't care of 'defined, this thing should certainly not exist anyway.

> and that, as far as I know, Arc isn't able to do for you.

You're certainly right here.

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