August 2014
Intermediate to advanced
120 pages
2h 45m
English
Content preview from Mastering Clojure Macros
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Approaching Hygiene with the Gensym
In order to avoid symbol capture issues like the one we just saw, Clojure gives us a few tools, all related to the gensym function. gensym’s job is simple: it produces a symbol with a unique name. The names will look funny because the name needs to be unique for the application, but that’s OK because we never need to type them into code:
| advanced_mechanics/gensym_2.clj | |
| | user=> (gensym) |
| | ;=> G__671 |
| | user=> (gensym) |
| | ;=> G__674 |
| | user=> (gensym "xyz") |
| | ;=> xyz677 |
| | user=> (gensym "xyz") |
| | ;=> xyz680 |
As you can see, any given invocation of gensym gives a unique value back—so if you want to refer to the same one twice, you’ll need to hold onto the value with a let binding or something similar. ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.