Using "isnull" function introduces a space between function name and opening parenthesis

[williamscs]

Describe the bug
Using SQL Server's "isnull" function introduces a space between function name and parentheses. This doesn't happen with other functions like "nullif".

To Reproduce
I used the main site's "try it out" section to reproduce.

Before fmt

select isnull(column, 'some string'), nullif(25, 25);

After fmt

select isnull (column, 'some string'), nullif(25, 25)
;

Expected behavior
I would expect 'isnull' to be treated the same as 'nullif' where there is no space between the function name and the parenthesis.

Actual behavior
A space is introduced.

[tconbeer]

That is because, in Postgres and other dialects, isnull is an operator that returns a boolean:

We can improve the parser to treat isnull( as a function instead.

[hongtron]

I'm noticing the same behavior with filter, which looks to be a keyword in Postgres, but is a function in SparkSQL:

             map_from_entries(
-                filter(
+                filter (
                     transform(

Should I open a separate issue for that, or can it be addressed here?

[tconbeer]

together is fine. thanks

[williamscs]

Thank you, @tconbeer !