Add lambda expression and map() + filter() functions with ARM syntax

[Gijsreyn]

PR Summary

This PR implements lambda expressions and the map() function for DSC configuration documents, enabling array transformations. The implementation uses ARM compatible syntax e.g., (lambda('param', body) and lambdaVariables('param'))

Example usage:

# Transform array elements
map(createArray(1, 2, 3), lambda('x', mul(lambdaVariables('x'), 2)))
# Returns: [2, 4, 6]

Seperated tests in a different file.

PR Context

Partially addresses #57.

[Copilot]

Pull Request Overview

This PR implements lambda expressions and the map() function for DSC configuration documents, using ARM-compatible syntax (lambda('param', body) and lambdaVariables('param')). The implementation stores lambdas in the context with unique UUID-based identifiers and evaluates them by binding lambda parameters to array elements.

Key changes:

• Added Lambda struct and lambda-specific handling in the function evaluation pipeline
• Implemented map(), lambda(), and lambdaVariables() functions for array transformations
• Extended Context with lambda storage (lambdas) and lambda parameter bindings (lambda_variables)

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
lib/dsc-lib/src/parser/functions.rs	Added Lambda struct and FunctionArg::Lambda variant; special handling for lambda() function to bypass normal evaluation
lib/dsc-lib/src/functions/mod.rs	Implemented invoke_lambda() to create and store lambda objects with UUID-based IDs; registered new lambda-related functions
lib/dsc-lib/src/functions/map.rs	Implemented array transformation function that evaluates lambdas for each element with optional index parameter
lib/dsc-lib/src/functions/lambda_variables.rs	Implemented parameter lookup function for accessing lambda-bound variables during evaluation
lib/dsc-lib/src/functions/lambda.rs	Created lambda function stub that returns error if invoked directly (handled specially elsewhere)
lib/dsc-lib/src/configure/context.rs	Added lambda_variables HashMap and lambdas RefCell for lambda storage and parameter binding
lib/dsc-lib/locales/en-us.toml	Added localized error messages and descriptions for lambda-related functions
dsc/tests/dsc_lambda.tests.ps1	Added integration tests for map() with various lambda scenarios (multiplication, index usage, range, empty array)

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[SteveL-MSFT]

LGTM

[SteveL-MSFT]

@Gijsreyn can you resolve the merge conflict and accept my suggestion to order then alpha?

[SteveL-MSFT]

@Gijsreyn can you accept my suggestion to alpha order the ArgKind and I can merge?

[Gijsreyn]

@SteveL-MSFT - my bad. I thought I had already pushed it. It's good to go!