Comprehensive SIMBA Implementation Comparison: DSPy vs DSPEx
Executive Summary
DSPEx has built excellent foundational infrastructure but is missing core algorithmic components. The implementation shows ~60% completion with strong engineering practices but incomplete optimization logic.
🏗️ Core Architecture & Infrastructure
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Module Structure | SIMBA class with helper functions | ✅ Complete | ⭐⭐⭐⭐⭐ | Excellent OTP design, proper behaviors |
Type System | Dynamic typing, minimal type hints | ✅ Superior | ⭐⭐⭐⭐⭐ | Comprehensive typespecs, enforced keys |
Error Handling | Basic try/catch blocks | ✅ Superior | ⭐⭐⭐⭐⭐ | Comprehensive error handling with telemetry |
Concurrency | Thread-based parallelism | ✅ Superior | ⭐⭐⭐⭐⭐ | Native BEAM concurrency with Task.async_stream |
Configuration | Constructor parameters | ✅ Complete | ⭐⭐⭐⭐ | Struct-based config with validation |
Documentation | Minimal docstrings | ✅ Superior | ⭐⭐⭐⭐⭐ | Comprehensive moduledocs and examples |
🧠 Core SIMBA Algorithm Components
Main Optimization Loop
Aspect | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Loop Structure | for step in range(max_steps): | ⚠️ Partial | ⭐⭐⭐ | Loop exists but missing key logic |
Iteration Management | Simple counter-based | ✅ Complete | ⭐⭐⭐⭐ | Proper Enum.reduce with state tracking |
State Management | Global variables | ✅ Superior | ⭐⭐⭐⭐⭐ | Immutable state threading |
Early Stopping | None | ❌ Missing | ⭐ | No convergence detection |
Python DSPy Reference:
for step in range(self.max_steps):
# 1. Get mini-batch
instance_idx = step * self.bsize
batch_indices = data_indices[instance_idx:instance_idx + self.bsize]
batch = [trainset[i] for i in batch_indices]
# 2. Prepare models and sample trajectories
models = prepare_models_for_resampling(programs[0], self.num_candidates)
top_programs = top_k_plus_baseline(self.num_candidates)
# 3-8. Core optimization steps...
DSPEx Current State:
# ✅ Good: Proper functional iteration
final_state = Enum.reduce(0..(config.max_steps - 1),
{programs, program_scores, winning_programs, next_program_idx},
fn step, {current_programs, current_scores, current_winning, prog_idx} ->
# ⚠️ Partial: Has structure but missing sophisticated logic
# ❌ Missing: Proper program selection algorithms
end)
Mini-batch Management
Aspect | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Batch Selection | Linear slice with wraparound | ✅ Complete | ⭐⭐⭐⭐ | get_circular_batch_indices works correctly |
Data Shuffling | random.shuffle(data_indices) | ✅ Complete | ⭐⭐⭐⭐ | Proper random shuffling with seed |
Batch Size Handling | Fixed batch size | ✅ Complete | ⭐⭐⭐⭐ | Handles edge cases properly |
🎯 Trajectory Sampling System
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Model Preparation | prepare_models_for_resampling() | ✅ Complete | ⭐⭐⭐⭐ | Temperature variation implemented |
Program Selection | Softmax sampling with scores | ❌ Broken | ⭐⭐ | Uses fixed scores (0.5), not real scores |
Execution Pairs | Simple (program, example) pairs | ⚠️ Over-complex | ⭐⭐ | Creates too many unnecessary pairs |
Parallel Execution | dspy.Parallel | ✅ Superior | ⭐⭐⭐⭐⭐ | Task.async_stream with proper error handling |
Trajectory Creation | Basic dict with score | ✅ Superior | ⭐⭐⭐⭐⭐ | Rich Trajectory struct with metadata |
Critical Issue in DSPEx:
defp softmax_sample(program_indices, _all_programs, temperature) do
if is_list(program_indices) and length(program_indices) > 0 do
scores = Enum.map(program_indices, fn _idx -> 0.5 end) # ❌ BROKEN: Fixed scores!
# Should calculate real scores from program performance
end
end
Python DSPy (Correct):
def softmax_sample(rng_obj, program_idxs, temperature):
scores = [calc_average_score(idx) for idx in program_idxs] # ✅ Real scores
exps = [np.exp(s / temperature) for s in scores]
# Proper probability sampling...
📊 Performance Analysis & Bucketing
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Bucket Creation | Sort by score, calculate gaps | ✅ Complete | ⭐⭐⭐⭐⭐ | Excellent implementation with metadata |
Performance Metrics | max_to_min_gap , max_to_avg_gap | ✅ Complete | ⭐⭐⭐⭐⭐ | All metrics properly calculated |
Bucket Sorting | Multi-criteria sorting | ✅ Complete | ⭐⭐⭐⭐ | Proper tuple-based sorting |
Statistical Analysis | Basic percentiles | ✅ Superior | ⭐⭐⭐⭐⭐ | Rich statistical metadata |
Both implementations handle this well, DSPEx is actually superior:
# ✅ DSPEx: Comprehensive bucket analysis
%Bucket{
trajectories: sorted_trajectories,
max_score: max_score,
min_score: min_score,
avg_score: avg_score,
max_to_min_gap: max_score - min_score,
max_to_avg_gap: max_score - avg_score,
metadata: %{
max_to_min_gap: max_to_min_gap,
max_to_avg_gap: max_to_avg_gap,
max_score: max_score,
avg_score: avg_score
}
}
🔧 Strategy System
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Strategy Interface | Function-based | ✅ Superior | ⭐⭐⭐⭐⭐ | Proper behavior with contracts |
AppendDemo Strategy | Full implementation | ✅ Complete | ⭐⭐⭐⭐⭐ | Excellent with Poisson sampling |
Strategy Selection | Random choice from list | ⚠️ Partial | ⭐⭐⭐ | Only tries first applicable strategy |
Multi-Strategy Support | Multiple strategies available | ❌ Limited | ⭐⭐ | Only AppendDemo implemented |
Rule-Based Strategy | append_a_rule() function | ❌ Missing | ⭐ | Not implemented |
Python DSPy Strategy System:
self.strategies = [append_a_demo(self.demo_input_field_maxlen), append_a_rule]
strategy = rng.choice(self.strategies) # Random selection
new_system = strategy(bucket, system_candidate, **strategy_kwargs)
DSPEx Strategy System:
# ✅ Good: Proper behavior definition
@behaviour DSPEx.Teleprompter.SIMBA.Strategy
# ✅ Excellent: AppendDemo implementation
defmodule DSPEx.Teleprompter.SIMBA.Strategy.AppendDemo do
# Full implementation with Poisson sampling
end
# ❌ Missing: Additional strategies like rule-based optimization
🧮 Program Pool Management
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Score Tracking | program_scores dict | ⚠️ Simplified | ⭐⭐⭐ | Basic Map structure, missing logic |
Program Selection | top_k_plus_baseline() | ❌ Missing | ⭐ | No sophisticated selection |
Winning Programs | List of best performers | ✅ Basic | ⭐⭐⭐ | Simple list, missing selection logic |
Score Calculation | calc_average_score() | ❌ Broken | ⭐ | Not properly implemented |
Program Registration | Dynamic index assignment | ⚠️ Partial | ⭐⭐ | Basic tracking without full logic |
Critical Missing Component:
# Python DSPy (Complete)
def calc_average_score(prog_idx):
scores = program_scores.get(prog_idx, [])
return sum(scores) / len(scores) if scores else 0.0
def top_k_plus_baseline(k):
scored_programs = sorted(programs, key=lambda p: calc_average_score(p.simba_idx), reverse=True)
top_k = [p.simba_idx for p in scored_programs[:k]]
if 0 not in top_k: # Ensure baseline is included
top_k = [0] + top_k[:k-1]
return top_k
# DSPEx (Missing sophisticated logic)
defp select_top_programs(programs, program_scores, num_candidates) do
# ❌ Oversimplified - missing the sophisticated selection logic
program_avg_scores = programs |> Enum.with_index() |> Enum.map(fn {_program, idx} ->
scores = Map.get(program_scores, idx, [])
avg_score = if Enum.empty?(scores), do: 0.5, else: Enum.sum(scores) / length(scores)
{idx, avg_score}
end)
# Missing proper baseline guarantee and selection logic
end
🎛️ Model Configuration & Sampling
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Temperature Variation | Dynamic temp adjustment | ✅ Complete | ⭐⭐⭐⭐ | Good temperature scaling |
Model Parameter Sampling | Basic temperature only | ✅ Complete | ⭐⭐⭐⭐ | Supports additional parameters |
LM Configuration | Simple copy with new temp | ✅ Superior | ⭐⭐⭐⭐ | More flexible configuration system |
📈 Evaluation & Scoring
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Candidate Evaluation | Batch evaluation on mini-batch | ✅ Complete | ⭐⭐⭐⭐ | Proper parallel evaluation |
Score Aggregation | Simple average | ✅ Complete | ⭐⭐⭐⭐ | Proper average calculation |
Final Selection | Max score selection | ✅ Complete | ⭐⭐⭐⭐ | Good selection logic |
Full Dataset Evaluation | End-of-optimization eval | ✅ Complete | ⭐⭐⭐⭐⭐ | Comprehensive final evaluation |
🔍 Bayesian Optimization Components
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Acquisition Function | Implicit in program selection | ❌ Missing | ⭐ | No Bayesian optimization |
Gaussian Process | Not explicitly used | ❌ Missing | ⭐ | Placeholder only |
Hyperparameter Search | Manual temperature tuning | ❌ Missing | ⭐ | No automated search |
Surrogate Model | Program performance history | ❌ Missing | ⭐ | No surrogate modeling |
Note: Python DSPy doesn’t use explicit Bayesian optimization either, but DSPEx has placeholder code suggesting it was planned.
🛠️ Engineering Quality & Observability
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Telemetry/Logging | Basic print statements | ✅ Superior | ⭐⭐⭐⭐⭐ | Comprehensive telemetry events |
Error Recovery | Basic exception handling | ✅ Superior | ⭐⭐⭐⭐⭐ | Graceful error handling |
Progress Tracking | None | ✅ Superior | ⭐⭐⭐⭐⭐ | Detailed progress callbacks |
Memory Management | Manual cleanup | ✅ Superior | ⭐⭐⭐⭐⭐ | Automatic GC, no memory leaks |
Testing Support | Limited | ✅ Superior | ⭐⭐⭐⭐⭐ | Comprehensive validation functions |
Correlation Tracking | None | ✅ Superior | ⭐⭐⭐⭐⭐ | Full request correlation |
📋 Data Structures & Types
Component | Python DSPy | DSPEx Status | Implementation Quality | Notes |
---|---|---|---|---|
Trajectory Representation | Dict with basic fields | ✅ Superior | ⭐⭐⭐⭐⭐ | Rich struct with metadata |
Bucket Structure | List with metadata dict | ✅ Superior | ⭐⭐⭐⭐⭐ | Proper struct with statistics |
Program State | Class attributes | ✅ Superior | ⭐⭐⭐⭐⭐ | Immutable state management |
Configuration | Constructor args | ✅ Superior | ⭐⭐⭐⭐⭐ | Structured config with validation |
🎯 Algorithmic Completeness Summary
Algorithm Phase | Python DSPy Implementation | DSPEx Implementation | Completion % |
---|---|---|---|
Initialization | ✅ Program setup, score tracking | ✅ Complete with better validation | 95% |
Mini-batch Selection | ✅ Circular indexing | ✅ Complete | 100% |
Model Preparation | ✅ Temperature variations | ✅ Complete | 100% |
Program Selection | ✅ Softmax sampling with real scores | ❌ Broken (fixed scores) | 30% |
Trajectory Sampling | ✅ (program, example) execution | ⚠️ Over-complex but functional | 70% |
Bucket Creation | ✅ Performance grouping | ✅ Complete and superior | 100% |
Strategy Application | ✅ Multiple strategies | ⚠️ Single strategy only | 60% |
Candidate Evaluation | ✅ Mini-batch evaluation | ✅ Complete | 100% |
Program Pool Update | ✅ Score tracking and selection | ⚠️ Basic tracking only | 40% |
Winning Program Selection | ✅ Top performer tracking | ⚠️ Simple list management | 60% |
Final Selection | ✅ Best program evaluation | ✅ Complete | 100% |
🚨 Critical Blocking Issues
1. Program Selection Algorithm (CRITICAL)
# ❌ BROKEN: Fixed scores instead of real performance scores
scores = Enum.map(program_indices, fn _idx -> 0.5 end)
Impact: Programs aren’t selected based on performance, breaking core SIMBA logic.
2. Missing Program Pool Management
# Python DSPy (Required)
def top_k_plus_baseline(k):
# Sophisticated program selection ensuring baseline + top performers
Impact: No intelligent program pool management, losing optimization efficiency.
3. Incomplete Strategy System
- Only
AppendDemo
implemented - Missing rule-based optimization
- No strategy diversity
4. Missing Score Calculation Logic
# Python DSPy (Required)
def calc_average_score(prog_idx):
scores = program_scores.get(prog_idx, [])
return sum(scores) / len(scores) if scores else 0.0
📊 Overall Implementation Status
Category | Completion | Quality | Priority |
---|---|---|---|
Infrastructure | 95% | ⭐⭐⭐⭐⭐ | ✅ Complete |
Data Structures | 100% | ⭐⭐⭐⭐⭐ | ✅ Complete |
Core Algorithm | 60% | ⭐⭐⭐ | 🚨 Critical gaps |
Strategy System | 40% | ⭐⭐⭐⭐ | ⚠️ Needs expansion |
Optimization Logic | 30% | ⭐⭐ | 🚨 Major rework needed |
Engineering Quality | 100% | ⭐⭐⭐⭐⭐ | ✅ Excellent |
🎯 Conclusion
DSPEx has built excellent foundational infrastructure with superior engineering practices, but the core SIMBA optimization algorithm is incomplete. The missing components aren’t minor features—they’re fundamental algorithmic pieces that make SIMBA work.
Key Strengths:
- Outstanding OTP/BEAM architecture
- Superior error handling and observability
- Excellent type system and documentation
- Well-designed data structures
Critical Gaps:
- Broken program selection (fixed scores instead of performance-based)
- Missing sophisticated program pool management
- Incomplete strategy system
- No real optimization logic driving program improvement
Estimated completion: ~60% overall, with critical algorithmic components missing that would require significant development to match DSPy’s functionality.