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Source for wiki PlebisciteObjections version 11

author

cowan

comment

ipnr

173.13.139.236

name

PlebisciteObjections

readonly

0

text

'''Work in progress, please ignore for now'''


* Adding Unicode support is too large a change from R5RS.
 * It is still possible for a Scheme to provide ASCII-only support; the only constraint is that it must be done in a way that extends smoothly to the rest of the Unicode repertoire.
* Exceptions integrate badly with the rest of the language.
 * Perhaps that is because they are pure R6RS.  We can't do it all.
* The syntaxes `#true` and `#false` are totally gratuitous.
 * They add a little extra readability, but are optional.  Early versions of the Scheme standard provided them in the forms `#!true` and `#!false`.
* The lexical syntax `#| ... |#` is unsightly.
 * A matter of taste.  Many Schemes provide it already, including R6RS.
* The lexical syntax `#!(no-)fold-case` is a bit ugly.
 * It is R6RS-compatible and fairly clear.  The alternatives `#cs` (case sensitive) and `#ci` are less widely standardized and less intuitively clear.
* The `read-line` procedure can cause a denial of service because it does not provide for a limit on the amount of input read.
 * True.  However, `read` has the same problem.  It's easy for an implementation that worries about this sort of thing to provide an optional second argument setting a limit.
* The `call/cc` abstraction is intractable and not useful and should have been excluded.
 * The WG did not believe that the very high bar for removing an IEEE Scheme feature was met.
* The draft was forbidden by its charter to remove restrictions that make additional features seem necessary.
 * If the restrictions in question were hard-coded into R5RS, and removing them would break backward compatibility, then yes.  Restrictions that could be removed without breaking backward compatibility could be and sometimes were removed; for example, the restriction that `load` loads into the interaction environment only.
* The large language should have been developed before the small language.
 * This objection is untimely.  In addition, developing a large language and then subsetting it would have a higher overall risk of failure; if the large language was never completed, the small language would not exist.
* The text-handling routines are redundant or inelegant in a Unicode world, but could not be removed or fundamentally altered due to charter restrictions.
 * Scheme would probably be better off not treating strings as sequences of characters, but rather treating characters as a special case of strings.  Unfortunately, that's too far away from the IEEE model.
* The interaction between exceptions, `dynamic-wind`, and continuations is missing something orthogonal.
 * This objection is too vague to meet head-on.
* The draft made many matters settled by R6RS undefined again.
 * Since R6RS support never became pervasive, these matters were in practice not defined in a way that Schemers could rely on, unless they used only R6RS-compatible implementations.
* The order of arguments in the draft's `bytevector-copy` is fundamentally incompatible with R6RS in an undetectable way, though it is R6RS that is wrong here.
 * True and unfortunate, but the draft's approach is consistent with the rest of Scheme.
* The draft should have included delimited continuation support.
 * The large language will provide it.
* The draft does not provide procedures that operate on mixed types of sequences (e.g. a map function that accepts a list and a vector and applies a two-argument function element-wise on them).
 * True.  Unfortunately, no one proposed them during the working life of WG1.
* The draft is too conservative in its changes to R5RS.
 * That was a charter requirement.
* #467 should not be reverted.

time

2013-05-13 16:56:38

version

11