[r6rs-discuss] [Formal] Declarations don't seem to be designed for real-world needs

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Summary: Declarations don't seem to be designed for real-world needs
Name: Jason Orendorff
Email: jason.orendorff_at_gmail.com
Issue Type: Enhancement
Priority: Minor
Component: Declarations
Version: 5.91
R5.91RS declarations strike me as odd.  The common use case for this
sort of feature is to make a debug build and a release build of the
same code.  In this use case, users often want debug builds to have
extra runtime checks (read: asserts) and sometimes extra debug output.
 Other use cases are extremely rare, in my experience, especially for
anything higher-level than a device driver.
This leads me to the following thoughts:
1. Source code is not a useful place for this sort of information.
2. The level of fine-grained expressivity provided by (declare) seems
excessive.  As a user, I never need anything beyond a single switch:
"safe" vs. "fast".  Even searching Makefiles for instances of gcc
compiler flags fails to bring up anything much more exotic than -O2.
3. To support the dominant use case, R6RS would need to allow code to
"see" the settings under which it's compiled.  You can't implement an
(assert) macro in R5.91RS, for example.
There seems to have been a lot of discussion on r6rs-editors about
"safe" and "unsafe", but not much about declarations as a language
feature.  The two are independent; R6RS could-- and perhaps should--
specify safe and unsafe modes without (declare) and the rest.
-j