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_quasistring.ss_; _quasistring_
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Abstract -------------------------------------------------------
The quasistring package provides convenient syntax for 
constructing strings that include computed values.

MACROS ---------------------------------------------------------

> (qs str) -> str
  qs requires a syntactic string as its argument.
  qs evaluates to the syntactic string it was provided, but with
  any occurrences of a dollar-sign followed by an s-expression
  in the string replaced by the evaluation of that s-expression
  in the current lexical context and converted to a string with
  _display_ (or by applying the value of the
  _current-quasistring-converter_ parameter to it).

  Literal dollar signs can be included in quasistrings by 
  escaping using a double-backslash.

  quasistring strings preserve eq-ness across multiple 
  evaluations of the same quasistring if the template string
  contains no s-expressions.

PARAMETERS ----------------------------------------------------

> (current-quasistring-converter) -> any? -> void
> (current-quasistring-converter any?) -> void

current-quasistring-converter is a parameter that accepts any
Scheme value and prints a character representation of it. 
The _qs_ macro uses this parameter to convert values to string
form; its default value is the mzscheme _display_ procedure.

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_qstr-lang.ss_; _quasistring language_
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_qstr-lang.ss_ is a wrapper for _quasistring.ss_ intended to
be used as a module language (i.e., an alternative to "mzscheme"
when specifying a module). All strings in modules written in 
qstr-lang.ss are quasistrings; the _qs_ macro is not required
(nor is it provided). 

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Known Issues
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By necessity, the quasistring library uses an approximation of
the source location for the expressions inside a quasistring. This
approximation assumes that programmers will use the smallest
character representation of any particular character that appears
in source code; for instance, it assumes that when it encounters the
character 'I' that the programmer literally typed 'I' rather than
\#111 or any of the other representations the character 'I' has. If
a programmer does use a non-minimally-small escape code for a 
character inside a quasistring, syntax-location information will be
incorrect for the remainder of that quasistring.