6.13.9 Procedures for Signaling Errors

Guile provides a set of convenience procedures for signaling error conditions that are implemented on top of the exception primitives just described.

Scheme Procedure: error msg arg …

Raise an error with key misc-error and a message constructed by displaying msg and writing arg ....

Scheme Procedure: scm-error key subr message args data

C Function: scm_error_scm (key, subr, message, args, data)

Raise an error with key key. subr can be a string naming the procedure associated with the error, or #f. message is the error message string, possibly containing ~S and ~A escapes. When an error is reported, these are replaced by formatting the corresponding members of args: ~A (was %s in older versions of Guile) formats using display and ~S (was %S) formats using write. data is a list or #f depending on key: if key is system-error then it should be a list containing the Unix errno value; If key is signal then it should be a list containing the Unix signal number; If key is out-of-range, wrong-type-arg, or keyword-argument-error, it is a list containing the bad value; otherwise it will usually be #f.

Scheme Procedure: strerror err

C Function: scm_strerror (err)

Return the Unix error message corresponding to err, an integer errno value.

When setlocale has been called (see Locales), the message is in the language and charset of LC_MESSAGES. (This is done by the C library.)

syntax: false-if-exception expr

Returns the result of evaluating its argument; however if an exception occurs then #f is returned instead.