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Alan Manuel Gloria: > Looks like you overlooked this e-mail: You're right, sorry about that. Thanks for pointing that out. > Here's another bit that seems a bit confusing... > > The approach does allow references to variable names with “-” > embedded in them without effort, > but the names must be spelled differently (and thus inconsistently) > by replacing every “-” with “_”. > Thus, variables like “list-ref” must > be spelled as “list_ref” inside the infix.plt notation > without effort. > > In particular the last "without effort" there seems to be something > that got left behind in some edit. > > I also think that the bit "The approach does allow references to > variable names with '-' embedded in them without effort," should be > "little effort" instead, as it's not actually *without* effort, users > having to translate - to _ after all. > > -- > > At the very least, it seems the bit "must be spelled as 'list_ref' > inside the infix.plt notation without effort." doesn't seem to scan > well. I'm not sure what you mean here by the "without effort" clause; > I suspect it's a mistake, but maybe you meant something else? Hmm. Okay, let's start with a discussion about what's *documented*, and then clarify the ramifications of the undocumented and useful |...| notation. That may make things clearer. Here's my attempt: ================================================= Many variables and operators are more difficult to refer to and/or must be spelled differently (and thus inconsistently). Its documentation states that identifiers (which are also used for function names) must “begin with a letter, and is optionally followed by series of letters, digits or underscores. An underscore is converted to a -”. Under these rules, it is not possible to call procedures with names like “<samp>char=?</samp>” or use variables with “*” embedded in them. It does allow references to variable names with “-” embedded in them, but in this approach names must be spelled differently (and thus inconsistently) by replacing every “-” with “_”. Thus, variables like “list-ref” must be spelled as “list_ref” inside the infix.plt notation as documented. The infix.plt documentation did not, at the time of this writing, document any way around this limitation. However, on 2012-10-21, Jens Axel Søgaard reported that other identifiers <em>can</em> be referred to using the |...| syntax. This works around the problem, but is slightly more cumbersome when it is necessary, and is inconsistent with other code where |...| is not required. These are fundamental side-effects of not <em>requiring</em> infix operators to be delimited (e.g., by whitespace). Since some symbols must be escaped with |...| inside infix.plt, yet they do not need to be escaped otherwise, this is an inconsistency, and this inconsistency can lead to potentially hard-to-find errors. ====================================================== --- David A. Wheeler