variable heads of terms

Hello

I'd like to be able to do something like the following:

X=reads, FACT=X(tom,book).

is there anything that will allow me to do this? Unfortunately, the
previous code gives the following error:

| ?- X=reads, FACT=X(tom,book).
uncaught exception: error(syntax_error('user_input:12 (char:16) . or
operator expected after expression'),read_term/3)

Thanks for any help you can provide!

CB