Module evaluator 

Scheme evaluator (eval loop)

Ported from OpenJade’s Interpreter.cxx (~2,000 lines).

Core Responsibilities

1. Evaluate expressions - Transform Values into results
2. Special forms - Handle if, let, define, lambda, quote, etc.
3. Function application - Call procedures with arguments
4. Tail call optimization - Prevent stack overflow in recursive functions

OpenJade Correspondence

Dazzle	OpenJade	Purpose
Evaluator	Interpreter	Main evaluator state
eval()	Interpreter::eval()	Core eval loop
apply()	Interpreter::apply()	Function application
eval_special()	Interpreter::evalXXX()	Special form handlers

Evaluation Rules (R4RS)

• Self-evaluating: Numbers, strings, booleans, characters → return as-is
• Symbols: Look up in environment
• Lists: First element determines behavior:
  • Special form keyword → handle specially
  • Otherwise → evaluate all elements, apply first to rest

Structs

CallFrame

A call stack frame

ConstructionRule

Construction rule for DSSSL processing

EvalError

Evaluation error with call stack

Evaluator

Scheme evaluator

EvaluatorContext

Context available to primitives during evaluation

ProcessingMode

Processing mode containing construction rules

Functions

get_evaluator_context

Get the current evaluator context (for use in primitives)

Type Aliases

EvalResult