Resilient lookups

# title: Resilient lookups
# category: Vibescript Showcase
# difficulty: Showcase
# summary: Recover from raised errors with rescue modifiers and probe float edge cases with nan? and finite?.
# description: 1.0 makes fetch raise on a miss and float division follow IEEE 754, so the rescue modifier and the float predicates are the idiomatic way to keep tolerant code readable.
# tags: reliability, errors, floats
# vibe: 0.4

def lookup_or(table: hash, key: symbol, fallback)
  table.fetch(key) rescue fallback
end

def safe_divide(a: int, b: int)
  (a / b) rescue nil
end

def run
  prices = { small: 5, large: 9 }
  infinity = 1.0 / 0.0
  not_a_number = 0.0 / 0.0

  {
    known: lookup_or(prices, :small, 0),
    unknown: lookup_or(prices, :huge, 0),
    divide_ok: safe_divide(100, 4),
    divide_guarded: safe_divide(100, 0),
    infinity_label: infinity.to_s,
    is_finite: (3.0 / 4.0).finite?,
    nan_detected: not_a_number.nan?,
    incomparable_is_nil: (1 <=> "a") == nil
  }
end