MultiGen Backend Comprehensive Comparison¶

Last Updated: October 15, 2025 Version: v0.1.83 Backends: 7 (C, C++, Rust, Go, Haskell, OCaml, LLVM)

Executive Summary¶

MultiGen supports 7 backends with varying levels of maturity:

6 Production-Ready: C++, C, Rust, Go, OCaml, LLVM (all 7/7 benchmarks)
1 Functionally Complete: Haskell (6/7 benchmarks, 86%)

Overall Benchmark Success: 48/49 runs (98% success rate)

Container Type Support¶

Backend	List Types	Dict Types	Set Types	Nested Containers
C++	`std::vector<int>`, `std::vector<float>`, `std::vector<double>`, `std::vector<string>`, nested vectors	`std::unordered_map<int,int>`, `std::unordered_map<string,int>`, `std::unordered_map<string,string>`	`std::unordered_set<int>`, `std::unordered_set<string>`	[x] Full - 2D arrays, nested vectors
C	`vec_int`, `vec_float`, `vec_double`, `vec_cstr`, `vec_vec_int`	`map_int_int`, `map_str_str`, `str_int_map`	`set_int`, `set_str`	[x] Full - 9+ types from 6 templates
Rust	`Vec<i32>`, `Vec<f64>`, `Vec<String>`, nested vectors	`HashMap<i32,i32>`, `HashMap<String,i32>`, `HashMap<String,String>`	`HashSet<i32>`, `HashSet<String>`	[x] Full with ownership tracking
Go	`[]int`, `[]float64`, `[]string`, nested slices	`map[int]int`, `map[string]int`, `map[string]string`	`map[T]bool` (sets as maps)	[x] Full via generics
Haskell	`[Int]`, `[Double]`, `[String]`, nested lists	`Data.Map.Map k v` (ordered)	`Data.Set.Set a` (ordered)	[x] Full with pure semantics
OCaml	`int list`, `float list`, `string list`, nested	`(k * v) list` (assoc lists)	Lists with deduplication	[!] Basic - uses lists
LLVM	`vec_int`, `vec_str`, `vec_vec_int*`	`map_int_int`, `map_str_int`	`set_int*`	[!] Partial - 2D arrays supported

Container Methods - Lists¶

Backend	append	insert	extend	remove	pop	clear	indexing	slicing	len
C++	[x] `push_back()`	[X]	[X]	[X]	[X]	[X]	[x] `[]`	[X]	[x] `size()`
C	[x] `vec_T_push()`	[X]	[X]	[X]	[x] `vec_T_pop()`	[x] `vec_T_clear()`	[x] `vec_T_at()`	[!] Limited	[x] `vec_T_size()`
Rust	[x] `push()`	[X]	[X]	[X]	[X]	[X]	[x] `[]`	[!] Limited	[x] `len()`
Go	[x] `append()`	[X]	[X]	[X]	[X]	[X]	[x] `[]`	[x] `[:]`	[x] `len()`
Haskell	[x] via `++`	[X]	[X]	[X]	[X]	[X]	[x] `!!`	[x] `take/drop`	[x] `length`
OCaml	[x] `list_append()`	[X]	[X]	[X]	[X]	[X]	[x] `List.nth`	[X]	[x] `List.length`
LLVM	[x] `vec_int_push()`	[X]	[X]	[X]	[X]	[X]	[x] `vec_int_at()`	[!] Limited	[x] `vec_int_size()`

Missing List Methods (All Backends)¶

insert(index, item) - Insert at position
extend(other) - Append multiple items
remove(item) - Remove first occurrence
reverse() - Reverse in-place
sort() - Sort in-place

Container Methods - Dicts¶

Backend	indexing	insert	get	contains (in)	keys	values	items	clear	erase/remove
C++	[x] `[]`	[x] `[]`	[x] `[]`	[x] `count()`	[X]	[x] `multigen::values()`	[x] iteration	[X]	[X]
C	[x] `map_KV_get()`	[x] `map_KV_insert()`	[x] `map_KV_get()`	[x] `map_KV_contains()`	[X]	[X]	[X]	[x] `map_KV_clear()`	[x] `map_KV_erase()`
Rust	[x] `get()/insert()`	[x] `insert()`	[x] `get()`	[x] `contains_key()`	[X]	[X]	[X]	[X]	[X]
Go	[x] `m[k]`	[x] `m[k]=v`	[x] `m[k]`	[x] `_, ok := m[k]`	[X]	[x] `MapValues()`	[x] `MapItems()`	[X]	[x] `delete()`
Haskell	[x] `Map.lookup`	[x] `Map.insert`	[x] `Map.lookup`	[x] `Map.member`	[x] `keys()`	[x] `values()`	[x] `items()`	[X]	[X]
OCaml	[x] assoc lookup	[x] cons	[X]	[x] `List.mem_assoc`	[X]	[X]	[X]	[X]	[X]
LLVM	[x] `map_KV_get()`	[x] `map_KV_insert()`	[x] `map_KV_get()`	[x] `map_KV_contains()`	[X]	[X]	[X]	[X]	[X]

Missing Dict Methods (Most Backends)¶

keys() - Returns list of keys (only Haskell)
values() - Returns list of values (C++, Go, Haskell)
items() - Returns key-value pairs (Go, Haskell)
get(key, default) - Safe access with default
clear() - Remove all items (only C)

Container Methods - Sets¶

Backend	add/insert	remove	discard	clear	contains (in)	union	intersection	difference
C++	[x] `insert()`	[X]	[X]	[X]	[x] `count()`	[X]	[X]	[X]
C	[x] `set_T_insert()`	[x] `set_T_erase()`	[x] `set_T_erase()`	[x] `set_T_clear()`	[x] `set_T_contains()`	[X]	[X]	[X]
Rust	[x] `insert()`	[X]	[X]	[X]	[x] `contains()`	[X]	[X]	[X]
Go	[x] `m[k]=true`	[x] `delete()`	[x] `delete()`	[X]	[x] `m[k]`	[X]	[X]	[X]
Haskell	[x] `Set.insert`	[X]	[X]	[X]	[x] `Set.member`	[x] `Set.union`	[x] `Set.intersection`	[x] `Set.difference`
OCaml	[x] via dedup	[X]	[X]	[X]	[x] `List.mem`	[X]	[X]	[X]
LLVM	[x] `set_int_insert()`	[X]	[X]	[X]	[x] `set_int_contains()`	[X]	[X]	[X]

Missing Set Methods (Most Backends)¶

remove(item) - Remove with error if missing (only C)
discard(item) - Remove without error (C, Go)
clear() - Remove all elements (only C)
Set operators: | (union), & (intersection), - (difference) - only Haskell

String Operations¶

Backend	upper	lower	strip	split	join	replace	find	startswith	endswith
C++	[x]	[x]	[x]	[x]	[X]	[x]	[x]	[X]	[X]
C	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[X]	[X]
Rust	[x]	[x]	[x]	[x]	[X]	[x]	[x]	[X]	[X]
Go	[x]	[x]	[x]	[x]	[X]	[x]	[x]	[X]	[X]
Haskell	[x]	[x]	[x]	[x]	[X]	[x]	[x]	[X]	[X]
OCaml	[x]	[x]	[x]	[x]	[X]	[x]	[x]	[X]	[X]
LLVM	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]

Missing String Methods (Most Backends)¶

startswith(prefix) - All except LLVM (v0.1.83)
endswith(suffix) - All except LLVM (v0.1.83)
join() - C++, Rust, Go, Haskell, OCaml (C and LLVM have it)

Built-in Functions¶

Backend	len	range	print	min	max	sum	abs	bool	enumerate	zip
C++	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[X]	[X]
C	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]
Rust	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[X]	[X]
Go	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[X]	[X]	[X]
Haskell	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[X]	[X]
OCaml	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[X]	[X]
LLVM	[x]	[x]	[x]	[x]	[x]	[x]	[x]	[X]	[X]	[X]

Missing Built-in Functions (Most Backends)¶

enumerate(iterable) - Only C backend
zip(*iterables) - Only C backend
sorted(iterable) - All backends
reversed(iterable) - All backends
all(iterable) - All backends
any(iterable) - All backends

Comprehensions Support¶

Backend	List Comp.	Dict Comp.	Set Comp.	Nested Comp.	Filters	Multiple Iterators
C++	[x] Lambda	[x] Lambda	[x] Lambda	[x]	[x]	[X]
C	[x] Loop	[x] Loop	[x] Loop	[x]	[x]	[X]
Rust	[x] Iterator	[x] Iterator	[x] Iterator	[x]	[x]	[X]
Go	[x] Reflection	[x] Reflection	[x] Reflection	[x]	[x]	[X]
Haskell	[x] Native	[x] `fromList`	[x] `fromList`	[x]	[x]	[X]
OCaml	[x] `List.map`	[x] Manual	[x] Dedup	[!] Limited	[x] `filter`	[X]
LLVM	[x] Loop	[x] Loop	[x] Hash set	[x]	[x]	[X]

Performance Metrics (from benchmark suite)¶

Execution Time (Average)¶

Rank	Backend	Avg Runtime	Notes
1	Go	64.5ms	Fastest execution
2	LLVM	152.9ms	2nd fastest, smallest binaries
3	Rust	249.3ms	Good balance
4	C++	254.9ms	Close to C
5	C	256.2ms	Expected performance
6	OCaml	287.2ms	Functional overhead
7	Haskell	288.5ms	Pure functional

Compilation Time (Average)¶

Rank	Backend	Avg Compile	Notes
1	Go	82.0ms	Fastest compilation
2	Rust	218.8ms	Good for safety guarantees
3	OCaml	258.1ms	Fast functional compiler
4	LLVM	330.7ms	IR generation overhead
5	C	384.1ms	Template expansion
6	C++	396.4ms	STL compilation
7	Haskell	536.9ms	Type inference overhead

Binary Size (Average)¶

Rank	Backend	Avg Size	Notes
1	C++	36.1KB	Smallest binaries
2	LLVM	37.0KB	Almost as small as C++
3	C	65.6KB	Template code
4	Rust	446.1KB	Safety metadata
5	OCaml	811.2KB	Runtime included
6	Go	2.3MB	Full runtime
7	Haskell	19.3MB	GHC runtime + libraries

Generated Code Size (Lines of Code)¶

Rank	Backend	Avg LOC	Notes
1	OCaml	27	Most concise
2	Haskell	27	Tied with OCaml
3	Rust	36	Compact Rust code
4	Go	37	Simple, readable
5	C++	49	STL verbosity
6	C	75	Manual memory management
7	LLVM	310	IR verbosity

Special Features & Characteristics¶

C++ Backend¶

Strengths:

[x] STL integration (best library support)
[x] Multi-pass type inference (most sophisticated)
[x] Lambda-based comprehensions (clean code)
[x] Smallest binaries (36KB average)
[x] Header-only runtime (357 lines)

Weaknesses:

[X] Slower compilation (396ms)
[X] Missing dict methods (keys, items)
[X] No list operations (insert, remove)

Best For: Production deployments requiring small binaries and C++ ecosystem integration

C Backend¶

Strengths:

[x] Template system (6 templates → 9+ types)
[x] Most complete runtime (2,500 lines)
[x] Strategy pattern for operations
[x] Full STC containers + fallback
[x] Only backend with enumerate/zip
[x] Most container methods (pop, clear, erase)

Weaknesses:

[X] Slowest compilation (384ms)
[X] Largest source code (75 LOC avg)
[X] Manual memory management

Best For: Systems programming, embedded, maximum control

Rust Backend¶

Strengths:

[x] Ownership-aware generation
[x] HashMap type inference (function call detection)
[x] Auto dereferencing/cloning
[x] Memory safety guarantees
[x] Fast compilation (218ms)

Weaknesses:

[X] Larger binaries (446KB)
[X] Missing container methods
[X] No dict.keys/values/items

Best For: Safety-critical applications, modern Rust codebases

Go Backend¶

Strengths:

[x] Fastest execution (64.5ms average)
[x] Fastest compilation (82ms)
[x] Generics (Go 1.18+)
[x] Reflection-based comprehensions
[x] Idiomatic Go patterns
[x] dict.values() and dict.items()

Weaknesses:

[X] Largest binaries (2.3MB)
[X] No bool conversion
[X] Sets via maps (not true sets)

Best For: Microservices, cloud deployments, performance-critical code

Haskell Backend¶

Strengths:

[x] Pure functional semantics
[x] Visitor pattern (main vs pure functions)
[x] Strongest type system
[x] Native set operations (union, intersection, difference)
[x] dict.keys/values/items support
[x] Most concise code (27 LOC)

Weaknesses:

[X] Largest binaries (19.3MB)
[X] Slowest compilation (536ms)
[X] 6/7 benchmarks (quicksort fails on mutation)
[X] Limited type inference for containers

Best For: Functional programming projects, academic research, provably correct code

OCaml Backend¶

Strengths:

[x] Most concise code (27 LOC)
[x] Fastest compile time among functional languages (258ms)
[x] Mutable references system with smart scoping
[x] Type-aware generation
[x] Sophisticated mutation detection
[x] Functional + imperative hybrid

Weaknesses:

[X] Uses association lists (not hash tables)
[X] Limited nested container support
[X] No dict.keys/values/items
[X] Basic set support via lists

Best For: Functional programming with mutations, OCaml ecosystem integration

LLVM Backend¶

Strengths:

[x] 2nd fastest execution (152.9ms)
[x] 2nd smallest binaries (37KB)
[x] Direct IR generation (no intermediate C/C++)
[x] Dual compilation modes (AOT + JIT)
[x] JIT: 7.7x faster development cycle
[x] Index-based set iteration
[x] Most complete string operations (9 methods including join, startswith, endswith) - v0.1.83
[x] Better error messages (descriptive runtime errors) - v0.1.83
[x] Memory-safe (ASAN verified, 0 leaks) - v0.1.82
[x] 107 comprehensive tests (723% increase) - v0.1.83

Weaknesses:

[X] Verbose IR (310 LOC average)
[X] Manual memory management (~8,300 lines C runtime)
[X] Newest backend (less mature)
[X] Limited OOP support
[X] No dict.keys/values/items

Best For: Research, compiler development, cross-platform targets, fast iteration (JIT), string-heavy applications

Benchmark Results Summary¶

Overall Success Rates¶

Backend	Success Rate	Benchmarks Passing	Status
C++	100% (7/7)	All	[x] Production
C	100% (7/7)	All	[x] Production
Rust	100% (7/7)	All	[x] Production
Go	100% (7/7)	All	[x] Production
OCaml	100% (7/7)	All	[x] Production
LLVM	100% (7/7)	All	[x] Production
Haskell	86% (6/7)	quicksort fails	[!] Functionally Complete

Benchmark Breakdown¶

Benchmark	C++	C	Rust	Go	Haskell	OCaml	LLVM
fibonacci	[x]	[x]	[x]	[x]	[x]	[x]	[x]
matmul	[x]	[x]	[x]	[x]	[x]	[x]	[x]
quicksort	[x]	[x]	[x]	[x]	[X]	[x]	[x]
list_ops	[x]	[x]	[x]	[x]	[x]	[x]	[x]
dict_ops	[x]	[x]	[x]	[x]	[x]	[x]	[x]
set_ops	[x]	[x]	[x]	[x]	[x]	[x]	[x]
wordcount	[x]	[x]	[x]	[x]	[x]	[x]	[x]

Haskell quicksort failure: "Function 'quicksort' mutates array in-place" - Conflicts with pure functional semantics

Type Inference Capabilities¶

Backend	Strategy	Constant	BinOp	Container Elements	Function Returns	Nested Types
C++	Multi-pass	[x]	[x]	[x] String-keyed dicts	[x]	[x] Vector of vectors
C	Strategy pattern	[x]	[x]	[x] Template-based	[x]	[x] 2D arrays
Rust	Strategy pattern	[x]	[x]	[x] HashMap detection	[x]	[x] Full
Go	Strategy pattern	[x]	[x]	[x] Reflection-based	[x]	[x] Full
Haskell	Basic	[x]	[!]	[!] Limited	[x]	[!] Limited
OCaml	Type-aware	[x]	[x]	[!] Limited	[x]	[!] Basic
LLVM	Comprehensive	[x]	[x]	[x] List/dict elements	[x]	[x] 2D support

Design Patterns by Backend¶

Pattern	C++	C	Rust	Go	Haskell	OCaml	LLVM
Strategy	[x] Type inference	[x] Type inference [x] Container ops	[x] Type inference	[x] Type inference	[x] Loop conversion	[x] Loop conversion	[X]
Visitor	[X]	[X]	[X]	[X]	[x] Statement conv	[X]	[X]
Factory	[X]	[x] Container creation	[X]	[X]	[X]	[X]	[X]
Template Method	[X]	[x] Parameterized templates	[X]	[X]	[X]	[X]	[X]

Design Pattern Impact:

C++/Rust/Go: 53→8 complexity (85% reduction) via Strategy
C: 66→10 complexity (85% reduction) via Strategy
Haskell: 69→15 complexity (78% reduction) via Visitor + 40→8 (80%) via Strategy
OCaml: 40→8 complexity (80% reduction) via Strategy

Memory Management¶

Backend	Model	Automatic Cleanup	Manual Management	Reference Counting	Ownership
C++	RAII	[x] Destructors	[X]	[X]	Move semantics
C	Manual	[X]	[x] `*_drop()`	[X]	Manual
Rust	Ownership	[x] Automatic	[X]	[x] `Rc<T>`	[x] Compiler-enforced
Go	GC	[x] Automatic	[X]	[X]	GC-managed
Haskell	GC	[x] Automatic	[X]	[X]	Pure functional
OCaml	GC	[x] Automatic	[X]	[X]	Ref cells
LLVM	Manual	[X]	[x] Explicit `free()`	[X]	Manual

Advanced Features¶

Feature	C++	C	Rust	Go	Haskell	OCaml	LLVM
Recursion	[x]	[x]	[x]	[x]	[x]	[x]	[x]
Mutual Recursion	[x]	[x]	[x]	[x]	[x]	[x]	[x]
Classes/OOP	[x]	[x] Structs	[x] Structs	[x] Structs	[x] Data types	[x] Records	[!] Limited
Inheritance	[X]	[X]	[X]	[X]	[X]	[X]	[X]
File I/O	[x]	[x]	[x]	[x]	[x]	[x]	[!] Limited
Module Imports	[x]	[x]	[x]	[x]	[x]	[x]	[!] Limited
Global Variables	[x]	[x]	[x]	[x]	[x]	[x]	[x]

Common Limitations (All Backends)¶

Not Implemented¶

[X] Exception handling (try/except/finally)
[X] Generators and yield statements
[X] Context managers (with statement)
[X] Decorators
[X] Async/await
[X] Metaclasses
[X] Multiple inheritance (most backends)
[X] Operator overloading (user-defined)

Partially Implemented¶

[!] Slicing (basic support, not full Python semantics)
[!] List methods (append only, no insert/remove/pop in most)
[!] Dict methods (no keys/values/items in most)
[!] Set operations (basic only, no operators)

Recommendations by Use Case¶

For Production Deployments¶

Best Choice: C++ or LLVM

Smallest binaries (36-37KB)
Good performance
No runtime dependencies
Mature ecosystems

For Development Speed¶

Best Choice: Go

Fastest compilation (82ms)
Fastest execution (64ms)
Simple code generation
Large binaries acceptable in cloud

For Safety-Critical Systems¶

Best Choice: Rust

Memory safety guarantees
Ownership tracking
No null pointer errors
Moderate binary size

For Functional Programming¶

Best Choice: Haskell or OCaml

Pure functional semantics (Haskell)
Hybrid functional/imperative (OCaml)
Concise code (27 LOC)
Strong type systems

For Embedded/Systems¶

Best Choice: C

Most complete runtime
Full control over memory
Template system
No external dependencies

For Research/Experimentation¶

Best Choice: LLVM

Direct IR access
JIT compilation (7.7x faster dev)
Cross-platform targets
Newest technology

Feature Completion Roadmap¶

Near Term (v0.1.x - v0.2.x)¶

Priority 1: Missing Container Methods

[ ] list.insert(index, item) - All backends
[ ] list.remove(item) - All backends
[ ] list.extend(other) - All backends
[ ] dict.keys() - C++, C, Rust, OCaml, LLVM
[ ] dict.values() - C, Rust, OCaml, LLVM
[ ] dict.items() - C++, C, Rust, OCaml, LLVM
[ ] set.remove(item) - C++, Rust, Haskell, OCaml, LLVM
[ ] set.clear() - C++, Rust, Go, Haskell, OCaml, LLVM

Priority 2: String Methods

[ ] str.join(iterable) - C++, Rust, Go, Haskell, OCaml ([x] C, [x] LLVM have it as of v0.1.83)
[ ] str.startswith(prefix) - C++, C, Rust, Go, Haskell, OCaml ([x] LLVM has it as of v0.1.83)
[ ] str.endswith(suffix) - C++, C, Rust, Go, Haskell, OCaml ([x] LLVM has it as of v0.1.83)

Priority 3: Built-in Functions

[ ] enumerate(iterable) - All except C
[ ] zip(*iterables) - All except C
[ ] sorted(iterable) - All backends

Long Term (v0.3.x+)¶

[ ] Exception handling (try/except)
[ ] Generators and yield
[ ] Context managers (with)
[ ] Advanced slicing
[ ] Set operators (|, &, -)
[ ] Tuple unpacking improvements

Conclusion¶

MultiGen offers 7 production-quality backends with different trade-offs:

Go: Best for cloud/microservices (fast execution, fast compilation)
C++/LLVM: Best for embedded/systems (small binaries)
Rust: Best for safety-critical (memory safety)
C: Best for maximum control (complete runtime)
Haskell/OCaml: Best for functional programming
LLVM: Best for research/experimentation (JIT mode)

Overall Quality: 98% benchmark success rate, 986 tests passing, strict type checking, design pattern implementations achieving 79% complexity reduction.

Maturity Level: 6 backends production-ready (100% benchmarks), 1 functionally complete (86% benchmarks).