Custom Query (1030 matches)

Alex Repenning reports that the Webkit example does not work in 1.2.

? (pprint (macroexpand '(setf (the double-float (aref a i)) val)))

(LET* ((#:G443 A) (#:G444 I))

(DECLARE (IGNORABLE #:G443 #:G444)) (MULTIPLE-VALUE-BIND (#:G445)

VAL

(LET ((#:G442 #:G445)) (ASET #:G443 #:G444 #:G442))))

From gb:

(declare (type (simple-array double-float) a b))

declares that A and B are SIMPLE-ARRAYs with unspecified dimensionality. We'll generally only try to open-code the AREF/CCL::ASET if the dimensionality of the array is specified in the declaration.

In "reasonably safe" code, if the declared dimensionality of the array was unpecified (or specified as *), we could treat

(aref a i)

as

(%typed-aref (type-of a) a i)

and typecheck that A is in fact a one-dimensional array of the declared type before doing anything with it. If A was in fact of the wrong dimensionality, we'd get a type error (A isn't a simple-one-dimensional-array of the specified type) rather than a wrong-number-of-subscripts error, but I don't think that AREF's error behavior is too rigidly specified. In unsafe code, we crash and burn if the actual dimensionality doesn't match, but win in more cases if it does.