--[[
Input (grammar) looks like this:

Apology ::= my (cat|mouse|monkey) ate my homework.
Apology ::= our (basement|attic|third floor) collapsed from an overload of school books.
]]

-- Put the grammar into array "rules".
rules = splitIntoLines(getSnippet("#229"))

-- Choose one of the rules (randomly).
rule = chooseOne(rules)

-- Parse rule: Apology ::= <bla>
bla = match(rule, "Apology ::= <bla>")

-- Parse bla into:
--   #1 (...)
--   #2 everything else

i = rule:find("([^)]*)"

With every s in #1 do:
  -- Split inner part of s at "|" into "options".
  options = split(inner, "|")
  -- Choose one of the options (randomly).
  option = chooseOne(options)
  -- Replace s with option.
  
-- Print bla (with the replacements made).
print(join(bla))