l: A new runtime for k and q

Original Article ↗ Hacker News Discussion ↗

What L Is and Why It Matters

  • L is described as a new runtime/interpreter for k and q/qSQL, the array languages behind kdb+, widely used for tick/time-series data in finance.
  • It aims for full language and database compatibility with existing k/q systems so users can run similar workloads locally, for free.
  • Several comments frame this as a big deal for quants who currently pay high prices for kdb+, especially as its vendor is seen as expensive and aggressive on IP.

Array Languages and Use Cases

  • k and q are characterized as terse, array-oriented languages in the APL/J family, where vectors/arrays are the primary mental and execution unit.
  • Commenters note that learning an array language often changes how one thinks about programming, beyond the niche financial use.
  • Some say the main practical motivation to learn q is access to highly paid jobs in finance and trading.

Performance, Design, and Benchmarks

  • L positions itself as a high-performance engine with:
    • Fusion of chained operations to avoid intermediates and enable in-place updates.
    • “Compute on compressed” vectors: using frame-of-reference–style compression to reduce bit-width (e.g., i64→i16/i8) and then operating directly on compressed data.
    • This is claimed to give large speedups for primitives like sum/avg by becoming more memory- and SIMD-efficient, addressing the memory wall.
  • Public benchmark suites are linked (master-benchmark, db-benchmark, TSBS), and readers are encouraged to run them themselves.
  • Some want direct comparisons against other k runtimes (including closed ones like Shakti). Current results are seen as promising but incomplete.

Website, “Vibecoding,” and AI Involvement

  • The landing page is widely described as “vibecoded”: cryptic copy, marketing phrases like “vector as unit of thought,” and minimal explanation for newcomers.
  • There is debate whether this is acceptable or a red flag. Some see it as a modern norm; others view it as a signal of uncertain quality.
  • The site explicitly states it was designed with Claude; the runtime is claimed to be hand-written.
  • The author reports using AI to analyze and optimize generated assembly, but not to write the core runtime.

Licensing and Openness

  • L is closed source, which many array-language enthusiasts accept as common in this ecosystem but others reject as a “non-starter.”
  • Some prefer existing open-source implementations as safer or more inspectable, while still finding L technically intriguing.