Re: psql \df choose functions by their arguments

This isn't working for arrays:
...
postgres=# \df aa aa int[]

I think it should use the same syntax as \sf and \ef, which require parenthesis
and commas, not spaces.

I think x is just used as "initial", so I think you should make it boolean and
then set is_initial = false, or similar.

+                                                                 pg_strcasecmp(functoken, "bool") == 0 ? "'boolean'"

I think writing this all within a call to appendPQExpBuffer() is excessive.
You can make an array or structure to search through and then append the result
to the buffer.