[gambit-list] Your changes to treatment of (begin)

Marc Feeley feeley at iro.umontreal.ca
Thu Dec 4 22:38:31 EST 2008


On 4-Dec-08, at 8:54 PM, Bradley Lucier wrote:

> An empty (begin) is not valid r5rs syntax, yet it's now accepted by  
> both the interpreter and the compiler.

Did you try it?

% gsi
Gambit v4.3.2

 > (list 11 (begin) 22)
*** ERROR IN (console)@1.10 -- Ill-formed special form: begin

Empty begins are illegal in expression context (as in the example  
above) and valid in "command" context as in this example:

% gsi
Gambit v4.3.2

 > (begin)
 > (let ((x 11)) (begin) 22)
22

So Gambit conforms to the R5RS spec closely...

The bug that was fixed is that an empty begin in expression context  
used to give a segmentation violation, now it gives an error message.

Marc




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