[Haskell-cafe] Re: Merging modules (again)

[pat browne]

Hi,
I have tried qualified imports, synonyms and newtypes but still I could
not implement the merging task (previously posted). This is probably
because I have little knowledge of Haskell *or* the task is not really
suited to Haskell (more of a specification task than a programming task).

My main questions are;
 Can the merging task be achieved using the Haskell module system?

I also posted a question on how this task could be done using type
classes. I would ask the same question with respect to type classes.

Regards,
Pat



pat browne wrote:
> Hi,
> I want to establish the strengths and weakness of the Haskell module
> system for the ontology merging task (I know it was not designed for
> this!). I wish to make a new module (MERGEDONTOLOGY) from three input
> modules one of which is common to the other two.
> The desired merge should contain the following data types:
>  Woman FinancialBank HumanBeing RiverBank
> Which are all identifiable without any qualifying module names.
> 
> Below is the detailed requirement and my first attempt at this task in
> Haskell. I would be grateful for any information on how to merge these
> modules giving a set of unique unqualified types (i.e. without reference
> to their originating modules).
> 
> Regards,
> Pat
> 
> 
> 
> 
> ========================
> Informal Specification
> ========================
> 
> The diagram and text below explain the requirement
> 
>                                    MERGEDONTOLOGY
>                   { Woman, RiverBank, FinancialBank, HumanBeing}
>                             /\                      /\
>                            /                         \
>                           /                            \
>                          /                              \
>                         /                                 \
>                        /                                   \
>                       /                                     \
> 
>                 ONTOLOGY1                              ONTOLOGY2
>         {Woman, Bank, Person}                       {Woman, Bank, Human}
>                      /\                                  /\
>                       \                                  /
>                         \                               /
>                          \                             /
>                            \                         /
>                             \                      /
>                              \                   /
>                               \                 /
>                                 {Woman ,  Person}
>                                    COMMMON
> 
> This example includes both synonyms and homonyms.
> 1)The Woman sort (or data type) should be the same in all modules, there
> is only one Woman sort and it is named as such in each module. Hence
> there should be only one MERGEDONTOLOGY.Woman.
> 
> 2)There is only one sort MERGEDONTOLOGY.HumanBeing, but there are 3
> synonyms for it called ONTOLOGY2.Human, ONTOLOGY1.Person, and
> COMMON.Person. The last sentence considers ONTOLOGY1.Person and
> COMMON.Person as synonyms; they have different qualifiers but the
> intention is that they represnt the same thing. Hence should be mapped
> to same MERGEDONTOLOGY.HumanBeing. To do this (in Maude) COMMON.Person
> was  renamed to ONTOLOGY2.Human which in turn was renamed to
> MERGEDONTOLOGY.HumanBeing.
> 
> 3)The homonyms are ONTOLOGY1.Bank and ONTOLOGY2.Bank should become
> distinct sorts MERGEDONTOLOGY.RiverBank and
> MERGEDONTOLOGY.FinancialBank in the final ontology at the top of the
> diagram.
> 
> 
> ================================================
> My first attemt at merging using Haskell modules
> =================================================
> module COMMON where
>  data  Woman = WomanC
>  data Person  = PersonC
> 
> 
> 
> module  ONTOLOGY1 where
>  import COMMON
>  data Bank = BankC
> 
> 
> module ONTOLOGY2 where
>  import COMMON
>  data Bank = BankC
> 
> 
> 
> module MERGEDONTOLOGY where
>   import ONTOLOGY1
>   import ONTOLOGY2
> 
> If I use qualified names all the constructors are interpreted correctly
>  MERGEDONTOLOGY> :t COMMON.WomanC
>  COMMON.WomanC :: COMMON.Woman
>  MERGEDONTOLOGY> :t COMMON.PersonC
>  COMMON.PersonC :: COMMON.Person
>  MERGEDONTOLOGY> :t ONTOLOGY2.BankC
>  ONTOLOGY2.BankC :: ONTOLOGY2.Bank
>  MERGEDONTOLOGY> :t ONTOLOGY1.BankC
>  ONTOLOGY1.BankC :: ONTOLOGY1.Bank
>  MERGEDONTOLOGY> :t COMMON.Woman
> 
> However, I wish that these types and constructors be fully defined in
> the context of the  MERGEDONTOLOGY. I have tried type synonyms and newtypes.
>   type RiverBank = ONTOLOGY1.Bank
>   type FinancialBank = ONTOLOGY2.Bank
>   newtype RiverBank = BankC Int
> I have not explored import modes or qualified imports.
> 
> 
>