This code looks like multiple variable assignment:
d:`a`b`c!1 2 3
d[`a`b]:10 20
Why is it working this way? And why it is not the same as (a;b):10 20 (which doesn't work)?
I suppose the 2nd line will make only temporary assignment - do not actually replace values. But it will.
It's indexing at top level and assigning new values so it would be the same as:
q)@[`d;`a`b;:;10 20]
`d
which also works for global variables in the root context
q)@[`.;`a`b;:;100 200]
`.
q)a
100
q)b
200