[basex-talk] hof:until is gone?

[Graydon Saunders]

Hello --

So I'm trying to do this:

import module namespace xcs = "http://www.xcential.com/xquery/utils/script";
at "same-words-same-order-script.xqm";
(: we don't need xc computationally but there are external variables in
that namespace in scope :)
import module namespace xc = "http://www.xcential.com/xquery/utils"; at
'same-words-same-order.xqm';

declare function xc:dropTableLines($in as node()*,$toggle as xs:boolean) as
node()* {
  switch (true())
    case empty($in) return ()
    case starts-with(head($in),':stab') return
(<line/>,xc:dropTableLines(tail($in),true()))
    case starts-with(head($in),':rtab') return
(<line/>,xc:dropTableLines(tail($in),false()))
    case $toggle return (<line/>,xc:dropTableLines(tail($in),$toggle))
    default return (head($in),xc:dropTableLines(tail($in),$toggle))
};

let $test as element() := <text>
  <line></line>
  <line></line>
  <line>:stab</line>
  <line>weasels</line>
  <line>:stab</line>
  <line>weasels</line>
  <line></line>
  <line></line>
  <line>:rtab.</line>
  <line></line>
  <line>asparagus</line>
  <line></line>
  <line></line>
  <line>:stab</line>
  <line></line>
  <line>weasels</line>
  <line>:rtab.</line>
  <line>asparagus</line>
  <line>asparagus</line>
  <line>asparagus</line>
  <line>asparagus</line>
  <line>asparagus</line>
  <line>:stab</line>
  <line>:stab</line>
  <line></line>
  <line></line>
  <line>:stab</line>
  <line></line>
  <line>weasels</line>
  <line></line>
  <line>:rtab.</line>
  <line></line>
  <line>asparagus</line>
  <line></line>
  <line></line>
  <line></line>
</text>

return element {'text'} {
            xc:dropTableLines($test/line,false())
          }

Only at scale the stack blows up and I get the "try tail recursion?"
suggestion. I would have tried hof:until for that, since I have to pass the
current state of "are we dropping or not dropping intervening content?",
but it looks like it's been removed? And the available hof functions in 4
look like they're strictly positional which is actively unhelpful in this
case. (At least with whatever brain cells I currently have.)

What's the appropriate pattern for "process a sequence, toggling an action
on or off based on the last member of the sequence we looked at?"

Thanks!
Graydon