Sport discrimination

SportEvent and Market are discriminated unions. The SDK’s TypeScript types let you narrow on a discriminator and access fields that only exist on the matching variant — without casts.

SportEvent.sport

SportEvent is the union BasketballMatch | FootballMatch | TennisMatch. The discriminator is sport:

client.on('sportEvent:added', ({ sportEvent }) => {
  if (sportEvent.sport === 'basketball') {
    sportEvent.homeTeam   // typed as string
    sportEvent.awayTeam   // typed as string
  } else if (sportEvent.sport === 'tennis') {
    sportEvent.competitor1  // typed as string
    sportEvent.competitor2  // typed as string
  } else if (sportEvent.sport === 'football') {
    sportEvent.homeTeam   // typed as string
  }
})

You can also narrow on kind, which is the underlying string discriminator ('se:basketball_match', etc.). sport is a computed convenience derived from kind — they always agree.

Market.kind

Market is a six-way union. Narrowing on kind reveals the variant fields:

for (const market of sportEvent.markets.values()) {
  if (market.kind === 'market:basketball_match.handicap') {
    market.handicap   // number, only on the handicap variant
    market.period     // BasketballPeriod
  } else if (market.kind === 'market:basketball_match.total') {
    market.cut        // total points threshold
    market.scope      // 'match' | 'home' | 'away'
  } else if (market.kind === 'market:basketball_match.player_prop_over_under') {
    market.playerName // string
    market.propType   // 'points' | 'rebounds' | …
    market.cut        // threshold
  }
}

The full list of MarketKind values is in Markets.

Selection.kind and Selection.result

Selection.kind mirrors the parent market’s selectionKind. Selection.result is the specific outcome:

for (const selection of market.selections.values()) {
  // selection.kind: 'over/under' | 'home/draw/away' | 'home/away' | 'competitor1/competitor2'
  // selection.result: 'over' | 'under' | 'home' | 'draw' | 'away' | 'competitor1' | 'competitor2'
}

result is constrained by kind — TypeScript will reject impossible combinations (e.g. result: 'draw' when kind: 'home/away').

Switch with satisfies for exhaustive coverage

function describe(market: Market): string {
  switch (market.kind) {
    case 'market:basketball_match.moneyline':  return 'basketball ML'
    case 'market:basketball_match.handicap':   return `basketball spread (${market.handicap})`
    case 'market:basketball_match.total':      return `basketball total ${market.cut}`
    case 'market:basketball_match.player_prop_over_under':
      return `${market.playerName} ${market.propType} O/U ${market.cut}`
    case 'market:football_match.moneyline':    return 'football 1X2'
    case 'market:tennis_match.moneyline':      return 'tennis ML'
  }
  market satisfies never  // TypeScript error if a kind is added without updating this switch
}

The market satisfies never pattern catches missing branches at compile time the next time a new market kind is introduced.