What is Texl?

[Brice Lambson (bricelam)]

I'm getting familiar with the codebase and was wondering what Texl means. Is it a play on T-SQL, like "T-SQL functions in Excel" shortened to "T-Excel" shortened to "Texl"?

[Darren Neese (Power Apps MVP) (PowerAppsDarren)]

Based on the code found here, Texl appears to be a core component of the Power Fx language implementation. The code suggests that "Texl" is an internal name for the type expression layer or type execution layer of Power Fx, though this is not explicitly documented in the source code.

Here are key insights:

Core Functionality

Base Class Purpose

• TexlFunction is an abstract base class that implements IFunction interface
• It provides the foundation for all function implementations in Power Fx
• Handles function signatures, parameter validation, and type checking

Key Features

• Supports lambda parameters through a mask system
• Handles function delegation to external data sources
• Manages function metadata and localization
• Processes type coercion and validation

Implementation Details

Function Properties

• Name and namespace management
• Return type validation
• Parameter type checking and coercion
• Delegation capabilities
• Error handling and reporting

Type System

• Supports complex type checking including tables and records
• Handles type coercion for parameters
• Manages column type validation
• Supports metadata type arguments

Delegation Support

• Enables server-side execution of functions
• Handles data source queries and operations
• Manages delegation capabilities and strategies

[McCall Saltzman (lesaltzm)]

Love the suggestion of T-Excel, but the actual answer is that the language that became Power Fx started life as a project called "Tangram". TEXL showing up in the code is a leftover from those days, a short form for "Tangram EXpression Language"