Write quant strategies in JavaScript.

BSL is an embedded JavaScript DSL. Your strategy is a single .js file that BitValue's research engine (Athena) runs bar-by-bar over 10+ years of market data. Edit the file, re-run the backtest — no recompile, no rebuild. The same source can later drive live execution, so what you backtest is what you trade.

Read the language spec → descriptor.json

Why BSL

Zero recompile

The strategy is data, not a binary. Change a rule or a parameter, re-run the backtest immediately.

JavaScript, not a toy DSL

Real variables, if, helper methods. Stateful logic (retest machines, counters) is just this.x — no custom-language gymnastics.

Backtest = live

One source feeds both research and signal generation, eliminating the Pine→engine rewrite drift.

Deterministic & sandboxed

No clock, no randomness, no I/O. Same inputs ⇒ same result, every time. Reproducibility is enforced, not hoped for.

What a strategy looks like

// @bsl bitvalue.io/schema/bsl/v1
strategy({
  name: "eth15m",
  params: { er_threshold_long: 60 },

  setup(p) {                          // runs once: build indicators
    this.er   = ind.ER(14);
    this.psar = ind.CustomATRPSAR(0.01, 0.03, 14);
  },

  onBar(c, pos, p) {                   // runs once per closed bar
    if (pos.flat && this.psar.trendDir === 1 && this.er.value >= p.er_threshold_long) {
      enterLong("TREND_LONG", { tp: [[.05,.30],[.10,.15]], sl: .03 });
    }
    if (pos.long && this.psar.flipped()) close("PSAR_EXIT");
    plot("Custom PSAR", this.psar.value);
  },
});

Build indicators in setup(); read them and emit at most one position action per bar in onBar(). Take-profit ladders and stop-losses are declared inline; the engine compiles them into protective orders. Full host API →

How it fits the platform

Write .js → Athena backtest → Golden-compare vs TradingView → Same source → live signals

Each strategy ships with a manifest — its identity, market, parameters, data needs, signal contract, risk constraints and admission state — the single source of truth shared by backtest and live so the two never drift.

For tools & AI agents: the language is defined at bitvalue.io/schema/bsl/v1 (human + machine-readable descriptor); the manifest schema at bitvalue.io/schema/strategy-manifest/v1 (human + JSON Schema). The // @bsl … header in every strategy dereferences to its definition.