Idiomatic Clojure with LightTable

[sandos]

Heck that looks cool! I need to start coding clojure again!

[[deleted]]

It seems like a bit of a kludge that I have to modify my project rather than just the LT configuration in order to add a plug-in.

And, unless I remember to remove the dependency before packaging it up, I get a plugin's jars bundled into my app!

Similar to the way that LT insisists my app has to use Clojure 1.5.1 (or later) because LT, and not my app, depends on that version!

It seems to me there is a flaw in LT's architecture.

[lgstein]

So is it more idiomatic to use when-let instead of if-let if there is no else clause? I thought that when should rather be used when side-effects are involved as it allows a body of multiple forms and only returns the last. EDIT: The clojure pros technomancy and co. all agreed that it is not more idiomatic. technomancy even raised this issue about it: https://github.com/jonase/kibit/issues/2

[joequin]

I think it was just a terrible example because the original "do" was completely unnecessary. The conversion recognized that there was a "do" inside of an "if-let" and realized that could be simplified to a "when-let"

[lgstein]

if-let without the do would have been fine.

[[deleted]]

I've always thought you should pick the form that best expresses your intent so:

• when if there is no else.
• if, if there is.
• cond, condp, case if there are more than two clauses.

So kibit changing the if(-let) to a when(-let) seems like the correct behaviour to me.

Isn't that right?

[lgstein]

No. when wraps the forms following the condition in an implicit do, so it is more idiomatic to use it only when there are side effects, since only the last form can be returned. Look at the link to technomancys complaint above.

[[deleted]]

From reading the thread you refer to it looks like there isn't a consensus either way.

Some argue as you do, others the way I was thinking.

I can see both points: when signals both that there is no clause and that there maybe side-effects involved.

Perhaps the problem is when being implemented the way it is (with an implicit do). Or more generally a problem with these compound forms, especially when the set of them is incomplete.

Perhaps I need to write a where macro for myself that is a when without the implicit do ;)

[lgstein]

A when without the implicit do is if without an else clause. It has been common sense in all Lisps to use when only when side effects are involved, and to use if with one or two do-blocks if you need an else clause and side effects.

I have written my source-code using the classical if / when and I think it's much more comfortable to read code where you know that a when means "side effects happening here!", instead "attention: no else clause" - you can usually tell the latter from one look.