Re: [polyml] Equality Type Parameter in Datatype Declaration

Many thanks Matthew for the clarification. Subtle :-) Since datatype declarations declare both a type operator and constructors, I think the explanation deserves to appear in http://mlton.org/EqualityTypeVariable, last part. The last two declarations declare identical type operators, but not

Re: [polyml] Equality Type Parameter in Datatype Declaration

Hello, Funnily (where my belief came from ?), the page about equality type variables on mlton.org (http://mlton.org/EqualityTypeVariable) says that they play no special role in either type bindings or datatype bindings, contradicting the compiler ... BB. On 9/16/16 10:42 PM, Bernard

Re: [polyml] Equality Type Parameter in Datatype Declaration

Bernard, That refers to a "type function" not a datatype binding. type ''a t = ''a * ''a creates a type function and indeed Poly/ML ignores the equality attribute in that case. A datatype binding creates a new "type name" and that is dealt with elsewhere. The fact that both mlton and hamlet

Re: [polyml] Equality Type Parameter in Datatype Declaration

> On 16 Sep 2016, at 20:59, Bernard Berthomieu > wrote: > > ... > I like the treatment of polyML :-), but I guess it is not standard: > > The "definition" (http://sml-family.org/sml97-defn.pdf) says, page 19: > "... In particular, the equality attribute has no

Re: [polyml] Equality Type Parameter in Datatype Declaration

Hello, Besides any printing/elaboration problem with polyml 5.6: In polyml 5.5: > datatype ''a t = C of ''a; datatype ''a t = C of ''a > C 1.0; Error-Type error in function application. Function: C : ''a -> ''a t Argument: 1.0 : real Reason: Can't unify ''a to real (Requires equality

Re: [polyml] Equality Type Parameter in Datatype Declaration

Rob, Actually what I was trying to find was the bit that says that the equality attribute in a type variable used as a datatype parameter should be honoured where it isn't when used as a type parameter. > type ''a t = ''a * ''a; type 'a t = 'a * 'a > (1.0, 2.0): real t; val it = (1.0, 2.0):

Re: [polyml] Equality Type Parameter in Datatype Declaration

David, > On 16 Sep 2016, at 19:19, David Matthews > wrote: > > I've checked hamlet and mlton and they both reject it so I think in this case > Poly/ML is right and SML/NJ is wrong. I can't point to the bit of the > definition that says that, though. It's in

Re: [polyml] Equality Type Parameter in Datatype Declaration

On 16/09/2016 16:12, Tjark Weber wrote: Hi, Is the following behavior (of Poly/ML 5.6) intended? > datatype ''a t = C of ''a; datatype 'a t = C of ''b I'll look at the printing here. There was a change in 5.5 that seems to have broken it. Moreover, Poly/ML rejects a following > C

[polyml] Equality Type Parameter in Datatype Declaration

Hi, Is the following behavior (of Poly/ML 5.6) intended? > datatype ''a t = C of ''a; datatype 'a t = C of ''b Moreover, Poly/ML rejects a following > C 1.0; while SML/NJ accepts it. Best, Tjark ___ polyml mailing list polyml@inf.ed.ac.uk