DEFAULT-CASE

[franz!frisky!jkf@ucbarpa.Berkeley.EDU (John Foderaro)]

    I brought up the issue of case-sensitive programming a few weeks
ago and there was no negative mail.   My message was part of the
discussion on the  READ-CASE-SENSITIVITY issue but in thinking it over
I believe that it makes more sense to look at what is needed to make
Common Lisp more useful in case-sensitive environments as two
separate things:  1. allow to the reader to be case-sensitive, and
2. make the names be lower-case by default.   Item 1 is already being
worked on, here is item 2:

						john foderaro
						franz inc.
						jkf%franz.uucp@berkeley.edu

	 

Issue:	DEFAULT-CASE
Forum:	Cleanup
References: CLtL p 334 ff: What the Read Function Accepts;
                especially p 337.
	    Issue: READ-CASE-SENSITIVITY
Category:   CHANGE
Edit History: 16-Mar-89, Version 1 by jkf

Problem Description:

    In most programming/operating-system environments where the case
    of names of functions, programs, identifiers, and files *does*
    matter, the case of most characters used for such purposes
    is lower case.   One example of such an environment is the Unix
    operating system.

    The resolution of the READ-CASE-SENSITIVITY will permit
    one to write case-sensitive Lisp code however since the 
    the case of characters in the print names of all standard
    functions and symbols is upper, this will make using
    the Lisp in a case-sensitive mode difficult.
    
Proposal (DEFAULT-CASE:LOWER)

    The case of all characters in the names of standard
    functions, symbols, and packages is lower.

Rationale:

    People running in a case-insensitive mode shouldn't care
    which case is the default case.

    People running in a case-sensitive mode care very much
    which case is default, and for most of these people
    lower case is preferred.

    Furthermore there are a large number of users
    of Lisp in case-sensitive environments and it is important
    that the desires of these users be met.

Current Practice:

    Franz Inc's Allegro Common Lisp supports a case-sensitive
    reader with either a upper-case default for names
    or a lower-case default.   A number of people use the
    case-sensitive feature with a lower-case default.  I don't
    know anyone that uses the lisp in a case-sensitive mode
    with an upper-case default.

Cost to Implementors:

    In case-insensitive mode, the cost to make characters downcase
    rather than upcase should be small.

    The cost of locating and fixing all of the places where
    the default case of symbol names actually matters will be moderate
    (I suspect that the older the Lisp the more numerous
    the instances of dependency on the case of the names).

Cost to Users:

    Again, the cost of locating and fixing all of the places where
    the default case of symbol names actually matters will be moderate.

    As an example, to find and fix all of the places in the PCL
    source (~15000 lines) that depend on the default case took
    me 15 minutes.

Cost of Non-Adoption:

    Using Lisp in case-sensitive environments will continue to be
    awkward.
    
    It will continue to be hard for Lisp to interact
    with programs written in case-sensitive languages (such as C).
    
    The use of case sensitivity as a tool for writing programs
    will continue to be unavailable to Lisp programmers.

    Vendors will invent their own methods of adding case-sensitivity,
    each in their own different way.
        
Benefits:

    See 'Cost of Non-Adoption'.

Aesthetics:

    Most Lisp books (including CLtL) put Lisp code in lower case.
    I believe that most people prefer to read text written in lower case.

    
Discussion:

    The best solution would be for there to be a way to make the
    reader case-sensitive (i.e. a resolution to the READ-CASE-SENSITIVITY
    issue) and for DEFAULT-CASE:LOWER to pass.  If for some
    reason the READ-CASE-SENSITIVITY should not be resolved in
    a manner that results in a case-sensitive reader option, it would
    still be good to pass DEFAULT-CASE:LOWER since that would
    bring Common Lisp one giant step closer to supporting the
    case-sensitive environment.

    
    
    
    
    
    
    
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