Re:Running Lisp in Production (2015)
by TeMPOraL on Sunday May 24, 2020 @05:49PM
(#23295142)
The common thing done with it is:
#+nil(this expression (won't be read))
(Also done with #+and, and #+or.)
This is an unofficial Common Lisp s-expression level comment. One of these incredibly nice things that's missing in most programming languages. It comments out a single s-expression, no matter how complex. It's like a #|block comment|# in that it can span multiple lines, and like ; line comment in that you only put something at the beginning. Have a complex expression within a function, that you need to temporarily shut down? Just shove #+nil in front of it.
(The #+nil version is discouragd because there's a remote chance somebody will define a * feature * called :nil for some reason.)
A less-common thing done with it is library interop. Many libraries tend to add a tag to * features * to indicate they've been loaded, so in your library, you can use #+library_tag to detect that another library is a part of the same project, and conditionally compile-in some extensions or interoperability code.
(@dang, I think HN could use a way to escape the * * formatting marks. For a site and community that has a soft spot for Lisp, not being able to type in the "earmuffs" is something that always bewildered me.)
This is an unofficial Common Lisp s-expression level comment. One of these incredibly nice things that's missing in most programming languages. It comments out a single s-expression, no matter how complex. It's like a #|block comment|# in that it can span multiple lines, and like ; line comment in that you only put something at the beginning. Have a complex expression within a function, that you need to temporarily shut down? Just shove #+nil in front of it.
(The #+nil version is discouragd because there's a remote chance somebody will define a * feature * called :nil for some reason.)
A less-common thing done with it is library interop. Many libraries tend to add a tag to * features * to indicate they've been loaded, so in your library, you can use #+library_tag to detect that another library is a part of the same project, and conditionally compile-in some extensions or interoperability code.
(@dang, I think HN could use a way to escape the * * formatting marks. For a site and community that has a soft spot for Lisp, not being able to type in the "earmuffs" is something that always bewildered me.)