> Although it is not currently possible to implement such a "retraction" > from OutputForm back to the given domain that generates these values > > coerce: A -> OuputForm > > could in principle be accompanied by > > retractIfCan: OutputForm -> Union(A,"failed")
Just a note related to that. In Aldor's libalgebra library, basically every mathematical domain inherits from ExpressionType. It basically says that an element can be transformed into an ExpressionTree. And there is also (additionally) a "Parsable" category. That has not yet anything to do with output, except that a domain that is of type ExpressionType inherits a default printing function that transforms the element into an expression tree and then uses that standard expression tree printing. OutputForm is in some sense like this expression tree and the printing is actually done by the interpreter. Printing is more explicitly visible in the library libaldor. Ralf --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/fricas-devel?hl=en -~----------~----~----~----~------~----~------~--~---
