Re: Argument Type Mismatch Errors

[Steven Haflich <smh@mit-ems.ARPA>]

	From: Robert R. Kessler <KESSLER@UTAH-20.ARPA>
	Subject: Argument Type Mismatch Errors
	
	Since the standard doesn't say that an error is required,
	couldn't one write a legal implementation of CL where it
	ignores the offending argument?

CLtL section 1.2.4 (pg.5) precisely defines what is required of an
implementation.  The short answer to your question is, yes, you can
write a valid CL with an append that ignores invalid arguments, but you
*cannot* write a valid CL program that exploits this behaviour!

Unofficially:  An implementation obviously should detect and signal
errors when convenient.  The primary force against always doing so is
run-time efficiency.  Personally, I feel that once an implementation
detects an error such as an inappropriate argument type, it should
always signal the error rather than silently proceeding.  There's no
reason not to signal the error, assuming the price of detecting it has
already been paid.