Changes between Version 18 and Version 19 of Records


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Timestamp:
Dec 29, 2011 4:48:48 PM (2 years ago)
Author:
GregWeber
Comment:

namespacing - TDNR & module ideas

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  • Records

    v18 v19  
    5151 
    5252 [http://code.google.com/p/frege/ Frege] takes this approach; see Sections 3.2 (primary expressions) and 4.2.1 (Algebraic Data type Declaration - Constructors with labeled fields) of the [http://code.google.com/p/frege/downloads/detail?name=Language-202.pdf Frege user manual]. 
     53 
    5354The module/record ambiguity is dealt with in Frege by preferring modules and requiring a module prefix for the record if there is ambiguity. So if your record named Record was inside a module named Record you would need `Record.Record.a`. I think for the most part programmers will structure their programs to avoid this situation. 
    5455 
    55  * '''Use the module name space mechanism'''; after all that's what it's for.  But putting each record definition in its own module is a bit heavyweight. So maybe we need local modules (just for name space control) and local import declarations.  Details are unclear. (This was proposed in 2008 in [http://www.haskell.org/pipermail/haskell-cafe/2008-August/046494.html this discussion] on the Haskell cafe mailing list and in #2551. - Yitz) 
     56Verbosity is solved in Frege by using the TDNR concept. In `data Record = Record {a::String};r = Record "A"; r.a` The final `r.a` resolves to `Record.a r`. 
     57 
     58 * '''Use the module name space mechanism'''; after all that's what it's for.  But putting each record definition in its own module is a bit heavyweight. So maybe we need local modules (just for name space control) and local import declarations.  Details are unclear. (This was proposed in 2008 in [http://www.haskell.org/pipermail/haskell-cafe/2008-August/046494.html this discussion] on the Haskell cafe mailing list and in #2551. - Yitz). 
     59 
     60Rather than strictly re-use modules it would make more sense to have a name-spacing construct that is shared between both records and modules - hopefully this would make implementation easier. 
    5661 
    5762'''Anyone who likes these designs, please fill out a detailed design, either here or on another page'''.