How to define a adverb

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1

Hello:
   New to Q.

   I’d like to define an adverb, that take a string-> string function f, and return a symbol to symbol function, like this:

`$ f string x 

But I can’t find anywhere on how to define an adverb. 

The below will fail.

mod_sym : {`$ x string y }

any helps?

2

Is this what you want.

q)f:{upper x}
q)f[“hello”]
“HELLO”
q)f1:{$x string y} q)f1[f;hello]
`HELLO

3

Yes, it’s . thanks. 
I think I made a mistake to use single quote ‘hello’ for string.