[plt-dev] coding ideas from JaneStreet

On Apr 13, Paulo J. Matos wrote:
> Eli Barzilay <eli at barzilay.org> writes:
> 
> > On Apr 12, Matthias Felleisen wrote:
> >> > 5. Code for exhaustiveness (pattern matches enumerate all
> >> >    conditions).
> >> 
> >> What you can see is that almost all of these apply to programming
> >> in PLT Scheme. Well, for 8, I will defer to Sam :-)
> >
> > #5 isn't in use outside of my class's language(s).
> 
> I was just going to ask how do you handle 5 in PLT Scheme. How can
> you force a match to actually make you exhaust all conditions?

The code that I'm talking about is a dialect of typed scheme that has
ML-like type definitions and matching, with the same kind of errors
when matches don't cover all cases, and when there are patterns that
are not reachable.  It's working only for these type definitions (not
on the usual scheme types, not on unions, etc -- only on types that
were defined using the ML-ish form).  But for the class it provides
the same advantage that ML has -- if you extend the AST definition
with a new variant, the compiler will tell you where you're missing
cases to deal with it.

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!