Hashes

Layer nested settings

Merge default, team, and user settings, resolving conflicts key by key.

Reference

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Sourceupstream/hashes/nested_settings.vibe
type Settings = hash<string, hash<string, string>>

def layer(base: Settings, override: Settings) -> Settings
  base.merge(override) { |section, mine, theirs| mine.merge(theirs) }
end

def changed(before: Settings, after: Settings) -> array<string>
  changes: array<string> = []
  after.each { |section, values|
    previous = before[section]
    values.each { |key, value|
      old = previous == nil ? nil : previous[key]
      shown = old == nil ? "unset" : old
      changes << "#{section}.#{key}: #{shown} -> #{value}" if old != value
    }
  }
  changes
end

def run -> { effective: Settings, changes: array<string>, theme: string }
  defaults: Settings = {
    display: { theme: "light", density: "comfortable" },
    alerts: { email: "daily", sms: "off" }
  }
  team: Settings = { alerts: { email: "instant" } }
  user: Settings = { display: { theme: "dark" }, privacy: { profile: "team" } }
  effective = layer(layer(defaults, team), user)

  {
    effective: effective,
    changes: changed(defaults, effective),
    theme: effective.fetch("display").fetch("theme", "light")
  }
end

Output

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