🚀 go-pugleaf

In article <91849@netnews.upenn.edu> freeman@linc.cis.upenn.edu (Jon Freeman) writes:
)
)I never even thought that writing a pretty-printer for SML was a
)feasible undertaking.  Consider the following program:
)
)--------------------------------------------------------------
)datatype foo = Alpha of int | Beta of real | Gamma of string;
)datatype bar = Happy of int | Dopey of real | Grumpy of string;
)
)fun testcase (x,y) =
)  case x of
)    Alpha _ => ()
)  | Beta _ =>
)      case y of
)        Happy _ => ()
)      | Dopey _ => ()
)      | Grumpy _ => ()
)  | Gamma _ => ();       (* Hmmm... *)
)--------------------------------------------------------------
)
)Any pretty-printer that can correctly indent the last line of testcase
)has to be able to discriminate between the constructors of foo and the
)constructors of bar!!  Does your pretty-printer really do this?  If
)so, I'm very impressed.

By the same token (so to speak), any parser for SML would also have to
be able to discriminate between the constructors of foo and those of bar
(at parse time!) if it were to parse this program as the author intends.
The given program is rejected by the SML/NJ compiler...

Bennet Vance