F# Type Provider for LQL with Compile-Time Validation

[MelbourneDeveloper]

F# Type Provider for LQL with Compile-Time Validation

TLDR;

Adds an F# type provider that validates LQL queries at compile time, converting them to SQL. Invalid LQL syntax causes compilation errors rather than runtime failures.

Brief Details

• LqlTypeProvider: New F# type provider (Lql.LqlCommand<"query">) that parses LQL at compile time, validates syntax, and generates SQL
• Compile-time errors: Invalid LQL queries fail the build with descriptive error messages including line/column positions
• Generated properties: Each validated query type exposes Query (original LQL) and Sql (generated SQL) static properties
• E2E test suite: 30+ tests covering selects, filters, joins, aggregations, ordering, limits, and arithmetic expressions
• Test data seeder: C# helper using DataProvider-generated extensions to seed test databases (no raw SQL inserts)
• CI integration: New GitHub Actions job lql-fsharp-typeprovider-tests runs F# type provider tests on LQL changes
• F# example project: Demo app showing type provider usage with .lql query files

How Do The Tests Prove This Works?

• TypeProviderCompileTimeValidationTests: Verify Query and Sql properties are generated correctly
• TypeProviderFilterTests: Confirm filter expressions generate proper WHERE clauses with AND/OR
• TypeProviderJoinTests: Validate JOIN, LEFT JOIN, and multi-table joins produce correct SQL
• TypeProviderAggregationTests: Test GROUP BY, SUM, AVG, COUNT, and HAVING clauses
• TypeProviderE2EExecutionTests: Execute generated SQL against real SQLite database, verify row counts and data
• TypeProviderRealWorldScenarioTests: End-to-end scenarios querying customers, filtering users, joining orders