REPL or print function

[vanillajonathan]

It seems there is no way to get the value of an variable or an expression.

let foo = 5 + 5

Now how do I know what is stored inside the foo variable?

I would love to have a print function so I could do:

let foo = 5 + 5
print foo

Or have a REPL where I could type things and it would evaluate them.

>>> 10 + 5
15
>>> let foo = 5 + 5
>>> foo
10

[max-sixty]

Currently PRQL only compiles to SQL; it can't actually execute much code itself

(it can actually execute 10 + 5, but that's not that useful on its own...).

So I don't think this is that easy; it would need a DB integration. I'll leave it open for any ideas though!

[vanillajonathan]

Yeah, I had a feeling that it would only compile to SQL. Theoretically a database could implement native support for PRQL though.

What got me thinking was the null handing chapter in the book that states that "null == null evaluates to true" and that "null != null evaluates to false" so I wanted a way to test that for myself.

I was also thinking it would be a useful feature to debug code and better understand what my variables contain.

[max-sixty]

Yes agree.

Check out the playground — that uses DuckDB, so you can evaluate small queries on some tables there.

The layout isn't that clear, we'd like to improve it.

[vanillajonathan]

I've been playing around with the playground a bit, but I've not been able to evaluate expressions and get the results of what is inside a variable in any other way than when using them as part of a query. It seems a from is required.

[max-sixty]

Yes this is true at the moment. You can do something like this. We'd like to make this much better. Possibly we allow a from null or allow no from (feel free to open an issue if this is something you'd like)