A single function to print the shell's state

[andychu]

Right now there is this hodgepodge:

shopt -p -o   # print POSIX global options, alternative to 'set -o'
shopt -p # print bash global options
declare -p  # print variables, with their flags.  note: this doesn't distinguish scopes
declare -f  # print functions  ('set' without args also doe sthis)
trap  # print traps

(not needed: ${var@a} because declare -p prints those flags)

and there's probably more...

• So Oil can either provide this function or provide an alternative. Maybe a generalization of the repr builtin
  • declare -p uses QSN now (well-defined string serialization). But you need eval because it looks like var=$'QSN'
  • trap takes a string of code, so it can also use QSN

Other formats:

• there could be some other consistent format, like the ASDL dump format that repr uses
  • is it parseable?
  • I think we mostly need a map, like (cell exported:T readonly:F nameref:F val:(value.Str ...))
    • although the type "tag" is also useful
• binary?

related to #704

[andychu]

This is also related to #708 because the stack is part of the shell's state