Formal comment #95 (defect)

Condition hierarchy
Reported by:	Andre van Tonder

Component:	exceptions
Version:	5.91

Summary: 

Minor defects in and comments on condition hierarchy. 

Description:

* For &warning conditions, I would suggest that if it were true that

"this type describes conditions that can safely be ignored", then no
warning would be necessary in the first place.

* I do not understand why &defect is necessary in addition to
* &violation.

I expect that the distinction will confuse users. 

* There seems to be no good reason why syntax-violation is not a defect but 

the other ...-violations, for example &undefined, are defects.

* If there was a mistake and &syntax is indeed also a &defect, then all 

the violations would be defects, and there would be no reason within
the existing hierarchy to have a &defect subtype separate from
&violation.

* If, on the other hand, it is indeed considered important to distinguish 

defects from just violations, I would suggest that the distinction be
reflected in the naming convention. For example,

- raise-contract-defect - undefined-defect? 

to distinguish from the mere violations: 

- raise-syntax-violation 

If, on the other hand, the distinction is not important enough to
reflect in the naming convention, I would suggest that it is not
important enough to have &defect in the first place as a separate
subtype.

* Under &syntax, the document states 

"This type describes syntax violations at the level of the library
syntax." This seems to suggest that &syntax violations are not meant
for scripts. It could also be taken to imply that &syntax violations
are only used for malformed "library" forms, and not, e.g., for
malformed "lambda" forms.

Suggestion: 

- Consider fixing minor description defects raised above. - COnsider
  dropping &defect as a simplification. The hierarchy isalready quite
  complicated.

RESPONSE:

The description of &warning will be revised in the next draft
to say that "this type describes conditions that do not, in
principle, prohibit immediate continued execution of the program, but
may interfere with the program's execution later."

The &defect condition type will be removed in the next draft

The wording "at the level of the library syntax" for &syntax will be
removed in the next draft.