Improve the usage of variable names in Scheme docstrings.

* module/ice-9/boot-9.scm:
* module/ice-9/popen.scm:
* module/ice-9/pretty-print.scm:
* module/ice-9/r4rs.scm:
* module/rnrs/io/ports.scm:
* module/texinfo/string-utils.scm:
* module/web/http.scm:
* module/web/request.scm:
* module/web/response.scm:
* test-suite/vm/run-vm-tests.scm: Make the variable names in Scheme docstrings more
  consistent.  Replace a few instances of @var with @code when appropriate.

module/ice-9/boot-9.scm

@@ -161,7 +161,7 @@ non-locally, that exit determines the continuation."
   (set! with-throw-handler
         (lambda (k thunk pre-unwind-handler)
           "Add @var{handler} to the dynamic context as a throw handler
-for key @var{key}, then invoke @var{thunk}."
+for key @var{k}, then invoke @var{thunk}."
           (if (not (or (symbol? k) (eqv? k #t)))
               (scm-error 'wrong-type-arg "with-throw-handler"
                          "Wrong type argument in position ~a: ~a"

module/ice-9/popen.scm

@@ -136,7 +136,7 @@
   "Executes the program @var{command} with optional arguments
 @var{args} (all strings) in a subprocess.
 A port to the process (based on pipes) is created and returned.
-@var{modes} specifies whether an input, an output or an input-output
+@var{mode} specifies whether an input, an output or an input-output
 port to the process is created: it should be the value of
 @code{OPEN_READ}, @code{OPEN_WRITE} or @code{OPEN_BOTH}."
   (let* ((port/pid (apply open-process mode command args))
@@ -148,7 +148,7 @@ port to the process is created: it should be the value of
 (define (open-pipe command mode)
   "Executes the shell command @var{command} (a string) in a subprocess.
 A port to the process (based on pipes) is created and returned.
-@var{modes} specifies whether an input, an output or an input-output
+@var{mode} specifies whether an input, an output or an input-output
 port to the process is created: it should be the value of
 @code{OPEN_READ}, @code{OPEN_WRITE} or @code{OPEN_BOTH}."
   (open-pipe* mode "/bin/sh" "-c" command))

module/ice-9/pretty-print.scm

@@ -298,7 +298,7 @@ port directly after OBJ, like (pretty-print OBJ PORT)."
                           (width 79)
                           (display? #f)
                           (breadth-first? #f))
-  "Print @var{obj}, truncating the output, if necessary, to make it fit
+  "Print @var{x}, truncating the output, if necessary, to make it fit
 into @var{width} characters. By default, @var{x} will be printed using
 @code{write}, though that behavior can be overriden via the
 @var{display?} keyword argument.

module/ice-9/r4rs.scm

@@ -39,14 +39,14 @@
   (@call-with-values producer consumer))
 (define (dynamic-wind in thunk out)
   "All three arguments must be 0-argument procedures.
-@var{in_guard} is called, then @var{thunk}, then
-@var{out_guard}.
+Guard @var{in} is called, then @var{thunk}, then
+guard @var{out}.
 
 If, any time during the execution of @var{thunk}, the
 continuation of the @code{dynamic_wind} expression is escaped
-non-locally, @var{out_guard} is called.  If the continuation of
-the dynamic-wind is re-entered, @var{in_guard} is called.  Thus
-@var{in_guard} and @var{out_guard} may be called any number of
+non-locally, @var{out} is called.  If the continuation of
+the dynamic-wind is re-entered, @var{in} is called.  Thus
+@var{in} and @var{out} may be called any number of
 times.
 @lisp
  (define x 'normal-binding)

module/rnrs/io/ports.scm

@@ -237,7 +237,7 @@ if the port has no transcoder."
   (not (port-encoding port)))
 
 (define (textual-port? port)
-  "Always returns @var{#t}, as all ports can be used for textual I/O in
+  "Always returns @code{#t}, as all ports can be used for textual I/O in
 Guile."
   #t)
 

module/texinfo/string-utils.scm

@@ -160,7 +160,7 @@ characters.  Any needed padding is done by character @var{chr}, which
 defaults to @samp{#\\space}.  If @var{rchr} is provided, then the
 padding to the right will use it instead.  See the examples below.
 left and @var{rchr} on the right.  The default @var{width} is 80.  The
-default @var{lchr} and @var{rchr} is @samp{#\\space}.  The string is
+default @var{chr} and @var{rchr} is @samp{#\\space}.  The string is
 never truncated.
 @lisp
  (center-string \"Richard Todd\" 24)
@@ -392,7 +392,7 @@ in @code{make-text-wrapper}."
 
 (define (fill-string str . kwargs)
   "Wraps the text given in string @var{str} according to the parameters
-provided in @var{keywds}, or the default setting if they are not
+provided in @var{kwargs}, or the default setting if they are not
 given.  Returns a single string with the wrapped text.  Valid keyword
 arguments are discussed in @code{make-text-wrapper}."
   (string-join (apply string->wrapped-lines str kwargs)

module/web/http.scm

@@ -205,7 +205,7 @@ header with name @var{sym}."
 (define (write-header sym val port)
   "Writes the given header name and value to @var{port}.  If @var{sym}
 is a known header, uses the specific writer registered for that header.
-Otherwise the value is written using @var{display}."
+Otherwise the value is written using @code{display}."
   (display (header->string sym) port)
   (display ": " port)
   ((header-writer sym) val port)

module/web/request.scm

@@ -217,7 +217,7 @@ on @var{port}, perhaps using some transfer encoding."
                             (bytevector-length bv) nbytes))))))
 
 (define (write-request-body r bv)
-  "Write @var{body}, a bytevector, to the port corresponding to the HTTP
+  "Write @var{bv}, a bytevector, to the port corresponding to the HTTP
 request @var{r}."
   (put-bytevector (request-port r) bv))
 

module/web/response.scm

@@ -226,7 +226,7 @@ on @var{port}, perhaps using some transfer encoding."
                             (bytevector-length bv) nbytes))))))
 
 (define (write-response-body r bv)
-  "Write @var{body}, a bytevector, to the port corresponding to the HTTP
+  "Write @var{bv}, a bytevector, to the port corresponding to the HTTP
 response @var{r}."
   (put-bytevector (response-port r) bv))
 

test-suite/vm/run-vm-tests.scm

@@ -67,7 +67,7 @@ it succeeded."
 (define (run-vm-tests files)
   "For each file listed in @var{files}, load it and run it through both the
 interpreter and the VM (after having it compiled).  Both results must be
-equal in the sense of @var{equal?}."
+equal in the sense of @code{equal?}."
   (let* ((res (map (lambda (file)
 		     (format #t "running `~a'...  " file)
 		     (if (catch #t