Clojurians Log v2
Clojure programming
Channels
Apps
startup-in-a-month
https://www.twitch.tv/a_fry_
bringe 2021-01-28T00:09:38.016300Z
So if you actually evaluate the whole comment form it doesn't evaluate any of the forms inside it. That's basically the point of it. When you use a comment form as a playground you need to evaluate each form inside it individually. In Calva, alt+enter if inside a form inside a comment form, will evaluate the top level form inside the comment.
bringe 2021-01-28T00:10:21.016500Z
So if you put your cursor in the first def like here: (def |hey "hey") and hit alt-enter the whole def form there will be evaluated, not the outer comment form.
bringe 2021-01-28T00:10:57.016700Z
It follows usual evaluation rules from within the comment form.
bringe 2021-01-28T00:11:17.016900Z
So if you wanted to eval all those defs at once for some reason, you could put them inside a do
bringe 2021-01-28T00:12:44.017100Z
Usually you'd be working with individual forms though. Maybe you want to try some code that has var names in it already - instead of using individual defs you could use one let.
(let [hey "hey"
wat "wat"]
(str hey wat))bringe 2021-01-28T00:22:48.018300Z
Sounds like you got the hang of it!
pez 2021-01-28T07:46:01.018600Z
Just want to add about the top-level evaluation inside comment forms. The way it is designed is that the comment form creates a new top level context. Let’s look at your example, @andyfry01:
(comment
(def hey "hey")
(def wat "wat")
(str hey w|at))| represents the cursor.) Since the comment form created a new top level context, what the top-level evaluator “sees” is this:
(def hey "hey")
(def wat "wat")
(str hey w|at)hey is not defined, well, you’ve seen what happens.Just want to add about the top-level evaluation inside comment forms. The way it is designed is that the comment form creates a new top level context. Let’s look at your example, @andyfry01:
(comment
(def hey "hey")
(def wat "wat")
(str hey w|at))| represents the cursor.) Since the comment form created a new top level context, what the top-level evaluator “sees” is this:
(def hey "hey")
(def wat "wat")
(str hey w|at)(str hey wat) that is then evaluated, and if hey is not defined, well, you’ve seen what happens. You expect the whole contents of the comment form to be evaluated. I can see why, but the thing is that if we didn’t treat comment forms special at all what would be evaluated is the whole comment form (not just it’s content) and that would give you nil.
Calva tries to make it easy for you to be in complete control of what is evaluated. So inside that Rich comment block you can move between redefining hey and then evaluate the str expression. You might not want to evaluate the last mentioned one at the same time (it could be expensive in some way). So, you are in control.
Sometimes we do want to evaluate a bunch of expressions in one go. For this Clojure gives us the do macro. So
(comment
(do
(def hey "hey")
(def wat "wat")
(str hey w|at)))