status: draft (2026-05-18)
keywords: Type Checking
See also SRFI 253: Data (Type-)Checking.
The original SRFI 253 established a basis for type-checked (or otherwise checked) data handling.
But it lacked some quality-of-life features.
This SRFI extends SRFI 253 to match existing implementation practice and common sense.
Provided extensions are:
check aliasing with define-check;
pre- and post-declaration of type / check with declare-checked;
return value checks
in lambda-checked, case-lambda-checked, and define-checked;
the check-of
and procedure-check-of
procedures to derive a suitable check for a datum / procedure;
and some optimizable checking patterns suggested to implementors.