> now one can make a pager like the unix 'more' utility in Picolisp. Reading
> the text from stdin and reading the keyboard to move around the text.
Yes, but still only in a limited way.
Utilities like 'more' or 'less' keep the standard input stream open
while at the same time reading the keyboard. For that, they conduct more
involved operations on the stream.
The proposed solution
(prinl (line)) ) )
works because first all data from the pipe are read, and only then from
the terminal. There is no way to switch back back to the original stream
after 'ctty' was called.