commit 714c30d01ba3cea224ebd27ee30c62b1345ffe03
parent 2e493bccbeacbe0efc5bb79b51019612143402c4
Author: Wolfgang Corcoran-Mathe <wcm@sigwinch.xyz>
Date: Mon, 5 Feb 2024 13:16:20 -0500
System: Tidy & reflow.
Diffstat:
1 file changed, 76 insertions(+), 73 deletions(-)
diff --git a/doc/r7rs-small/procedures/system-interface.texinfo b/doc/r7rs-small/procedures/system-interface.texinfo
@@ -1,26 +1,27 @@
@node System interface
@section System interface
-Questions of system interface generally fall outside of the domain of this report.
-However, the following operations are important enough to deserve description here.
+Questions of system interface generally fall outside of the domain of
+this report. However, the following operations are important enough to
+deserve description here.
@deffn {load library procedure} load filename
@deffnx {load library procedure} load filename environment-specifier
It is an error if @var{filename} is not a string.
-An implementation-dependent operation is used to transform
-@var{filename} into the name of an existing file
-containing Scheme source code. The @code{load} procedure reads
-expressions and definitions from the file and evaluates them
-sequentially in the environment specified by @var{environment-specifier}.
-If @var{environment-specifier} is omitted, @code{(interaction-environment)}
-is assumed.
+An implementation-dependent operation is used to
+transform @var{filename} into the name of an existing
+file containing Scheme source code. The @code{load}
+procedure reads expressions and definitions from the file and
+evaluates them sequentially in the environment specified by
+@var{environment-specifier}. If @var{environment-specifier} is
+omitted, @code{(interaction-environment)} is assumed.
-It is unspecified whether the results of the expressions
-are printed. The @code{load} procedure does not affect the values
-returned by @code{current-input-port} and @code{current-output-port}.
-It returns an unspecified value.
+It is unspecified whether the results of the expressions are printed.
+The @code{load} procedure does not affect the values returned by
+@code{current-input-port} and @code{current-output-port}. It returns
+an unspecified value.
@rationale{}
@@ -34,9 +35,8 @@ implementations.
It is an error if @var{filename} is not a string.
-The @code{file-exists?} procedure returns
-@code{#t} if the named file exists at the time the procedure is called,
-and @code{#f} otherwise.
+The @code{file-exists?} procedure returns @code{#t} if the named file
+exists at the time the procedure is called, and @code{#f} otherwise.
@end deffn
@@ -44,113 +44,115 @@ and @code{#f} otherwise.
It is an error if @var{filename} is not a string.
-The @code{delete-file} procedure deletes the
-named file if it exists and can be deleted, and returns an unspecified
-value. If the file does not exist or cannot be deleted, an error
-that satisfies @code{file-error?} is signaled.
+The @code{delete-file} procedure deletes the named file if it
+exists and can be deleted, and returns an unspecified value. If the
+file does not exist or cannot be deleted, an error that satisfies
+@code{file-error?} is signaled.
@end deffn
@deffn {process-context library procedure} command-line
-Returns the command line passed to the process as a list of strings. The first string
-corresponds to the command name, and is implementation-dependent. It is an error to
-mutate any of these strings.
+Returns the command line passed to the process as a list of
+strings. The first string corresponds to the command name, and is
+implementation-dependent. It is an error to mutate any of these
+strings.
@end deffn
@deffn {process-context library procedure} exit
@deffnx {process-context library procedure} exit obj
-Runs all outstanding dynamic-wind @var{after} procedures, terminates the
-running program, and communicates an exit value to the operating system.
-If no argument is supplied, or if @var{obj} is @code{#t}, the
-@code{exit} procedure should communicate to the operating system that the
-program exited normally. If @var{obj} is @code{#f}, the @code{exit}
-procedure should communicate to the operating system that the program
-exited abnormally. Otherwise, @code{exit} should translate @var{obj} into
-an appropriate exit value for the operating system, if possible.
+Runs all outstanding dynamic-wind @var{after} procedures, terminates
+the running program, and communicates an exit value to the operating
+system. If no argument is supplied, or if @var{obj} is @code{#t},
+the @code{exit} procedure should communicate to the operating system
+that the program exited normally. If @var{obj} is @code{#f}, the
+@code{exit} procedure should communicate to the operating system
+that the program exited abnormally. Otherwise, @code{exit} should
+translate @var{obj} into an appropriate exit value for the operating
+system, if possible.
-The @code{exit} procedure
-must not signal an exception or return to its continuation.
+The @code{exit} procedure must not signal an exception or return to
+its continuation.
-Note: Because of the requirement to run handlers, this procedure is not just the
-operating system's exit procedure.
+Note: Because of the requirement to run handlers, this procedure is
+not just the operating system's exit procedure.
@end deffn
@deffn {process-context library procedure} emergency-exit
@deffnx {process-context library procedure} emergency-exit obj
-Terminates the program without running any
-outstanding dynamic-wind @var{after} procedures
-and communicates an exit value to the operating system
-in the same manner as @code{exit}.
+Terminates the program without running any outstanding dynamic-wind
+@var{after} procedures and communicates an exit value to the operating
+system in the same manner as @code{exit}.
@end deffn
@deffn {process-context library procedure} get-environment-variable name
Many operating systems provide each running process with an
-@dfn{environment} consisting of @dfn{environment variables}.
-(This environment is not to be confused with the Scheme environments that
+@dfn{environment} consisting of @dfn{environment variables}. (This
+environment is not to be confused with the Scheme environments that
can be passed to @code{eval}: see @ref{Environments and evaluation}.)
Both the name and value of an environment variable are strings.
-The procedure @code{get-environment-variable} returns the value
-of the environment variable @var{name},
-or @code{#f} if the named
-environment variable is not found. It may
-use locale information to encode the name and decode the value
-of the environment variable. It is an error if
-@code{get-environment-variable} can't decode the value.
+The procedure @code{get-environment-variable} returns the value of the
+environment variable @var{name}, or @code{#f} if the named environment
+variable is not found. It may use locale information to encode the
+name and decode the value of the environment variable. It is an
+error if @code{get-environment-variable} can't decode the value.
It is also an error to mutate the resulting string.
@lisp
(get-environment-variable "PATH")
-@result{} "/usr/local/bin:/usr/bin:/bin"
+ @result{} "/usr/local/bin:/usr/bin:/bin"
@end lisp
@end deffn
@deffn {process-context library procedure} get-environment-variables
-Returns the names and values of all the environment variables as an alist, where the car
-of each entry is the name of an environment variable and the cdr is its value, both as
-strings. The order of the list is unspecified. It is an error to mutate any of these strings
-or the alist itself.
+Returns the names and values of all the environment variables as an
+alist, where the car of each entry is the name of an environment
+variable and the cdr is its value, both as strings. The order of the
+list is unspecified. It is an error to mutate any of these strings or
+the alist itself.
@lisp
(get-environment-variables)
-@result{} (("USER" . "root") ("HOME" . "/"))
+ @result{} (("USER" . "root") ("HOME" . "/"))
@end lisp
@end deffn
@deffn {time library procedure} current-second
-Returns an inexact number representing the current time on the International Atomic
-Time (TAI) scale. The value 0.0 represents midnight on January 1, 1970 TAI (equivalent to
-8.000082 seconds before midnight Universal Time) and the value 1.0 represents one TAI
-second later. Neither high accuracy nor high precision are required; in particular,
-returning Coordinated Universal Time plus a suitable constant might be the best an
-implementation can do.
+Returns an inexact number representing the current time on the
+International Atomic Time (TAI) scale. The value 0.0 represents
+midnight on January 1, 1970 TAI (equivalent to 8.000082 seconds before
+midnight Universal Time) and the value 1.0 represents one TAI second
+later. Neither high accuracy nor high precision are required; in
+particular, returning Coordinated Universal Time plus a suitable
+constant might be the best an implementation can do.
As of 2018, a TAI-UTC offset table can be found at [40].
@end deffn
@deffn {time library procedure} current-jiffy
-Returns the number of @dfn{jiffies} as an exact integer that have elapsed since an arbitrary,
-implementation-defined epoch. A jiffy is an implementation-defined
-fraction of a second which is defined by the return value of the
-@code{jiffies-per-second} procedure. The starting epoch is guaranteed to be
-constant during a run of the program, but may vary between runs.
+Returns the number of @dfn{jiffies} as an exact integer that have
+elapsed since an arbitrary, implementation-defined epoch. A jiffy is an
+implementation-defined fraction of a second which is defined by the
+return value of the @code{jiffies-per-second} procedure. The starting
+epoch is guaranteed to be constant during a run of the program, but may
+vary between runs.
@rationale{}
Jiffies are allowed to be implementation-dependent so that
-@code{current-jiffy} can execute with minimum overhead. It
-should be very likely that a compactly represented integer will suffice
-as the returned value. Any particular jiffy size will be inappropriate
-for some implementations: a microsecond is too long for a very fast
+@code{current-jiffy} can execute with minimum overhead. It should be
+very likely that a compactly represented integer will suffice as the
+returned value. Any particular jiffy size will be inappropriate for
+some implementations: a microsecond is too long for a very fast
machine, while a much smaller unit would force many implementations to
return integers which have to be allocated for most calls, rendering
@code{current-jiffy} less useful for accurate timing measurements.
@@ -159,8 +161,8 @@ return integers which have to be allocated for most calls, rendering
@deffn {time library procedure} jiffies-per-second
-Returns an exact integer representing the number of jiffies per SI second. This value is
-an implementation-specified constant.
+Returns an exact integer representing the number of jiffies per SI
+second. This value is an implementation-specified constant.
@lisp
(define (time-length)
@@ -174,8 +176,9 @@ an implementation-specified constant.
@deffn procedure features
-Returns a list of the feature identifiers which cond-expand treats as true. It is an error to
-modify this list. Here is an example of what @code{features} might return:
+Returns a list of the feature identifiers which cond-expand treats as
+true. It is an error to modify this list. Here is an example of what
+@code{features} might return:
@lisp
(features) @result{}
