link strings
link weaving

procedure pfl2str(pattern)
   local result, expr1, expr2, op
   static symbols, optbl

   initial {
      symbols := '[]*`~Ð><+|#:!'

      optbl := table()

      optbl["*"] := repl
      optbl["`"] := reverse
      optbl["#"] := rotate
      optbl["<"] := Upto
      optbl[">"] := Downto
      optbl["Ð"] := UpDownto
      optbl["|"] := PatternPalindrome
      optbl["!"] := Palindrome
      optbl["+"] := Block
      optbl["~"] := Collate
      optbl["Ð>"] := Extend
      optbl["~"] := Interleave
      optbl[":"] := Template
      optbl["?"] := Permute
      optbl["%"] := Pbox
      optbl["><"] := UpDown
      optbl["<>"] := DownUp
      }

   result := ""

   pattern ? {
      while result ||:= tab(upto('[')) do {
         move(1)
         expr1 := pfl2str(tab(bal(symbols, '[', ']'))) |
            error()
         op := tab(many(symbols)) | error()
         expr2 := pfl2str(tab(bal(']', '[', ']'))) | error()
         result ||:= \optbl[op](expr1, expr2) | error()
         move(1)
         }
      if not pos(0) then result ||:= tab(0)
      }

   return result

end