MathAction #425 confusion over Category

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The file algebra/domain.spad.pamphlet contains this definition:

  )abbrev domain CATEGORY Category
  ++ Author: Gabriel Dos Reis
  ++ Date Create: February 16, 2008.
  ++ Date Last Updated: February 16, 2008.
  ++ Basic Operations: coerce
  ...

but OpenAxiom does not always treat Category this way:

axiom)show Category
 Category  is a domain constructor
 Abbreviation for Category is CATEGORY
 This constructor is not exposed in this frame.
 Issue )edit /usr/local/lib/open-axiom/x86_64-unknown-
linux/1.2.0-2008-05-25/src/algebra/CATEGORY.spad to see algebra source code for
CATEGORY
------------------------------- Operations --------------------------------
 coerce : % -> OutputForm

axiom
Category

(1)

Type: Type

axiomx:Category
   Category is a category, not a domain, and declarations require
      domains.

axiom
Category has Category

(2)

Type: Boolean

axiom
Domain has Category

(3)

Type: Boolean

axiom
Category has Type

(4)

Type: Boolean

... --Bill Page, Wed, 28 May 2008 17:13:05 -0700 reply

Axiom Version: => /usr/local/lib/open-axiom/x86_64-unknown-linux/1.2.0-2008-05-25

category regression --gdr, Wed, 28 May 2008 17:55:47 -0700 reply

hat is a regression, because the rest of the compiler and interpreter assumes that Category is conceptually a category -- even when it has a domain implementation.

what? --Bill Page, Wed, 28 May 2008 18:39:35 -0700 reply

gdr wrote:

  Category is conceptually a category -- even when it has a domain implementation

Could you please explain what that means? :-)

... --gdr, Wed, 28 May 2008 20:48:32 -0700 reply

At the conceptual level, OpenAxiom thinks of Category as a category. The category of categories. However, it has a domain implementation, e.g. as reported by )show. That is just an implementation detail.

domains belong to Category --gdr, Wed, 28 May 2008 22:06:22 -0700 reply

OpenAxiom trunk as of 2008-05-29 says this:

 (5) -> Category has Category

   (5)  true
                             Type: Boolean

 (6) -> Domain has Category

   (6)  true
                             Type: Boolean

 (7) -> Category has Type

   (7)  true
                             Type: Boolean

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