Switches

There are a number of binary switches that control the behavior of the command processor. They can be set using the ,set and ,unset commands.

,set switch [on | off | ?]
This sets the value of mode-switch switch. The second argument defaults to on. If the second argument is ? the value of switch is is displayed and not changed. Doing ,set ? will display a list of the switches and their current values.

,unset switch
,unset switch is the same as ,set switch off.

The switches are as follows:

batch
In `batch mode' any error or interrupt that comes up will cause Scheme 48 to exit immediately with a non-zero exit status. Also, the command processor doesn't print prompts. Batch mode is off by default.

auto-levels
Enables or disables the automatic pushing of a new command level when an error, interrupt, or other breakpoint occurs. When enabled (the default), breakpoints push a new command level, and <eof> (see above) or ,reset is required to return to top level. The effects of pushed command levels include:

• a longer prompt
• retention of the continuation in effect at the point of errors
• confusion among some newcomers

With auto-levels disabled one must issue a ,push command immediately following an error in order to retain the error continuation for debugging purposes; otherwise the continuation is lost as soon as the focus object changes. If you don't know anything about the available debugging tools, then levels might as well be disabled.

inspect-focus-value
Enable or disable `inspection' mode, which is used for inspecting data structures and continuations. Inspection mode is desribed below.

break-on-warnings
Enter a new command level when a warning is produced, just as when an error occurs. Normally warnings only result in a displayed message and the program does not stop executing.

ask-before-loading
If on, the system will ask before loading modules that are arguments to the ,open command. Ask-before-loading is off by default.

> ,set ask-before-loading
will ask before loading modules
> ,open random
Load structure random (y/n)? y
>

load-noisily
When on, the system will print out the names of modules and files as they are loaded. load-noisily is off by default.

> ,set load-noisily
will notify when loading modules and files
> ,open random
[random /usr/local/lib/scheme48/big/random.scm]
> 

inline-values
This controls whether or not the compiler is allowed to substitute variables' values in-line. When inline-values mode is on, some Scheme procedures will be substituted in-line; when it is off, none will. The performance section has more information.

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