-11703

213233

K: Best (Known so far) Practice

	Variable Detection	How do you detect he presence or absence of a variable without causing an error?	I
(1)	. `sym	Appears to produce value of str in current directory or null	DN
(2)	d`str	Same, so long as d exists	SA
(3)	.[d;`str;:]	Doesn't seem to have any paricular advantage / disadvantage over (2)	GH
(4)	(#!_d)~(!_d)?`str	Allows distinguishing `defined but null' from `not defined'	GH
	Conclusion	Not Yet Established

	Directories	How do you select Directories from a list of files?	II
(1)	f@&~(@!:)'f	Given list of files f shows Dirs (Links?)	EL,SA
	Conclusion	Not Yet Established

	File Characteristics	How can you get file attributes in a K program?	III
(1)	Code is Here	An approach using the Windows DIR command has been coded for NT, ME, 98 and Win2K	DN
	Conclusion	Not Yet Established

	Windows Version	How can you figure out which Windows is running in a K program?	IV
(1)	Code is Here	The ver function returns which Windows Version is running.	DN
	Conclusion	Not Yet Established

	Enlist a Scalar	How can you `enlist' a scalar without enlisting a list in K program?	V
(1)	V:{:[@x;,x;x]}	If x is an atom enlist it, otherwise leave it alone	BA
(2)	l,()	Appending a null list leaves list alone, but converts scalar to list	SS
	Conclusion	(2) looks hard to beat. No disadvantages have been reported yet.

	Iterators	How can you see the effect of K's interators?	VI
(1)	Code is Here	Shows the effect of the execution of K's interators.	DN
	Conclusion	Not Yet Established