Skip to contentSkip to content
Verified credentials. On-chain. Forever.Learn more
Cover image for Build a Lexer and Parser for a Domain Query Language
Code

Build a Lexer and Parser for a Domain Query Language

FreeVerified credential3 weeksIntermediate

Overview

What this challenge is about.

Take the 1-page grammar sketch and the 12,000-query corpus (anonymized). Hand-write a lexer that emits tokens with source positions (line and column). Build a recursive-descent parser that produces a typed AST matching the evaluator's existing schema (provided). Cover the existing operators (and / or / not / between / in / regex-match), function calls, and parenthesized expressions. Emit human-readable error messages with a caret pointing at the offending column on any parse failure. Pass 100 percent of the corpus and a 60-case hand-curated edge-case suite (unclosed strings, trailing operators, deeply nested groups).

CredentialBlockchain-anchored
ShareableLinkedIn-ready
LanguageEnglish
PaceSelf-paced

The Brief

What you'll do, and what you'll demonstrate.

Replace a regex-based query parser with a clean lexer plus recursive-descent parser that handles 12,000 real queries and produces useful error messages.

Earning criteria — what you'll demonstrate

  • Implement a hand-written lexer with source-location tracking
  • Build a recursive-descent parser for a non-trivial expression grammar
  • Design an AST that decouples syntax from evaluation
  • Produce diagnostic messages a non-compiler engineer can act on

Program Fit

Where this fits in your program.

Sharpens the same skills your degree expects you to demonstrate.

Skills

Skills you'll demonstrate.

Each one shows up on your verified credential.

Careers

Roles this prepares you for.

Real titles. Real skill bridges. Pick the one closest to your trajectory.

Career mappings coming soon.

One more thing

You can put a credential on your CV by Friday.