Transformation of CST (Concrete Syntax Tree) to Pattern Subject.

This module provides functions to transform parsed gram notation (CST) into the core Pattern Subject representation. The default behavior preserves anonymous subjects as 'Symbol ""' to enable round-trip compatibility, while optional functions are available for explicit ID assignment when needed.

Design Decision: Anonymity Preservation by Default

The default transformGram function preserves anonymous subjects (represented as 'Symbol ""') rather than assigning generated IDs. This enables true round-trip compatibility: parsing and serializing anonymous patterns preserves their anonymous nature.

When to Use ID Assignment

Use transformGramWithIds or assignIdentities when:

• You need unique identifiers for graph algorithms
• You need to distinguish between anonymous instances
• You're working with external systems that require explicit IDs

Use transformGram (default) when:

• You need round-trip compatibility
• You want to preserve the original gram notation structure
• Anonymous subjects should remain anonymous

Examples

>>> transformGram (parseGram "()")
Pattern with Subject {identity = Symbol "", ...}

>>> transformGramWithIds (parseGram "() ()")
Pattern with two subjects having identities Symbol "#1" and Symbol "#2"