Hi Kurt,
You do not need to create a new domain. It also fails to work with XDP
in the latest master.
Actually, if I am not wrong than "A has C" only tells you that C is
explicitly mentioned in the exports of A, but not whether there is an
actual implementation for C.
(1) -> Expression Integer has SemiRing
(1) true
(2) -> R ==> Expression Integer
(3) -> SYM ==> Symbol
(4) -> XDP ==> XDistributedPolynomial(SYM,R)
(5) -> [x::XDP for x in [X,Y,Z]]
(5) [X, Y, Z]
Type: List(XDistributedPolynomial(Symbol,Expression(Integer)))
(6) -> [a,b,c] := [x::XDP for x in [X,Y,Z]]
(6) [X, Y, Z]
Type: List(XDistributedPolynomial(Symbol,Expression(Integer)))
(7) -> a
(7) X
Type: XDistributedPolynomial(Symbol,Expression(Integer))
(8) -> r := a*b^2*c^4
2 4
(8) X Y Z
Type: XDistributedPolynomial(Symbol,Expression(Integer))
(9) -> retract r
Function: retractIfCan : % -> Union(FreeMonoid(Symbol),"failed") is
missing from domain: XDistributedPolynomial(Symbol,Expression(Integer))
Internal Error
The function retractIfCan with signature
(Union (FreeMonoid (Symbol)) failed)$ is missing from domain
XDistributedPolynomial(Symbol)(Expression (Integer))
(9) -> R
(9) Expression(Integer)
(10) -> R has SemiRing
(10) true
(11) -> XDP has RetractableTo(FreeMonoid SYM)
(11) true
However, looking down the implementation chain tells me that retract
should be implemented through FreeModule(R,FreeMonoid SYM). But we have
(12) -> F := FreeModule(R,FreeMonoid SYM)
(12) FreeModule(Expression(Integer),FreeMonoid(Symbol))
(13) -> F has RetractableTo(FreeMonoid SYM)
(13) true
(16) -> s := 'x::Symbol
(16) x
Type: Symbol
(17) -> sf := s :: F
(17) x
Type: FreeModule(Expression(Integer),FreeMonoid(Symbol))
(18) -> retract sf
(18) x
Type: FreeMonoid(Symbol)
So indeed, your detected error is weird.
In fact, when you enter XDistributedPolynomial into HyperDoc browse, add
the parameters vl=Symbol and R=Expression Integer, click on Operations
and then on Implementation, it also tell you that retractIfCan is
nowhere implemented.
My suspicion is that it has something to do with the conditional
implementation of retract in FreeModule. I faintly remember that I once
had a similar issue.
Looks like someone must use "git bisect run" to find out which commit
causes the issue.
Ralf
Ralf
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