$ fq -i
null> 1+1
2
null> (
error: repl:1:2: unexpected token <EOF>
null> abc
error: repl:1:0: function not defined: abc/0
null> 1+"a"
error: cannot add: number (1) and string ("a")
null> 1 | repl
> number> .+1
2
> number> ^D
null> [1,2,3] | repl({}; .[])
> number, ...> .
1
2
3
> number, ...> ^D
null> [] | repl({}; .[])
> empty> 1
> empty> ^D
null> ^D
$ fq -i 'empty'
empty> 1
empty> ^D