lispsyntax-acset

Bidirectional S-expression ↔ ACSet conversion inspired by OCaml's ppx_sexp_conv

Version: 1.1.0 Trit: 0 (Ergodic - coordinates data serialization) Bundle: serialization Dynamic Sufficiency: ✅ VERIFIED (2025-12-22) - handles ACSets of arbitrary complexity

Overview

This skill bridges LispSyntax.jl (Lisp-like syntax in Julia) with ACSets.jl (algebraic databases) using the pattern established by OCaml's ppx_sexp_conv library. It enables:

1. S-expression parsing: parse_sexp("(+ 1 2)") → Sexp
2. ACSet serialization: sexp_of_acset(graph) → Sexp
3. ACSet deserialization: acset_of_sexp(GraphType, sexp) → Graph
4. Colored S-expressions: Gay.jl deterministic coloring via SplitMix64

OCaml Inspiration

(* OCaml pattern *)
type color = Red | Blue | Green [@@deriving sexp]
(* generates: sexp_of_color and color_of_sexp *)

# Julia equivalent for ACSets
sexp_of_acset(acs::ACSet) → Sexp
acset_of_sexp(::Type{T}, ::Sexp) → T where T <: ACSet

Core API

Sexp Type (matches OCaml)

abstract type Sexp end
struct Atom <: Sexp
    value::String
end
struct SList <: Sexp
    children::Vector{Sexp}
end

Parsing & Serialization

# String → Sexp (like OCaml's Sexp.of_string)
sexp = parse_sexp("(define (square x) (* x x))")

# Sexp → String (like OCaml's Sexp.to_string)
str = to_string(sexp)

# Roundtrip verification
@assert verify_parse_roundtrip("(a (b c) d)")

Primitive Converters (like Sexplib.Std)

# To S-expression
sexp_of_int(42)           # → Atom("42")
sexp_of_float(3.14)       # → Atom("3.14")
sexp_of_string("hello")   # → Atom("hello")
sexp_of_list(sexp_of_int, [1,2,3])  # → SList([1, 2, 3])

# From S-expression
int_of_sexp(Atom("42"))   # → 42
list_of_sexp(int_of_sexp, SList([...]))  # → [1, 2, 3]

ACSet Conversion

# ACSet → Sexp
# Produces: (TypeName (Ob1 ((id1 attrs...) ...)) (hom1 ((src tgt) ...)) ...)
sexp = sexp_of_acset(my_graph)

# Sexp → ACSet
graph = acset_of_sexp(GraphType, sexp)

# Verify roundtrip
@assert verify_roundtrip(original_graph)

Colored S-expressions (Gay.jl)

# Colorize with deterministic seed
colored = colorize(sexp, seed=0x598F318E2B9E884)
# ColoredSexp with LCH color from SplitMix64

Output Format

ACSet to S-expression produces structured output:

(Graph
  (V ((1) (2) (3)))           ; Vertices (object parts)
  (E ((1) (2)))               ; Edges (object parts)
  (src ((1 1) (2 2)))         ; Source morphism (id → target)
  (tgt ((1 2) (2 3))))        ; Target morphism (id → target)

GF(3) Triad Integration

Trit	Skill	Role
-1	slime-lisp	Validates Lisp syntax
0	lispsyntax-acset	Coordinates serialization
+1	cider-clojure	Generates Clojure interop

Conservation: (-1) + (0) + (+1) = 0 ✓

Integration with Existing Skills

thread_relational_hyjax.hy

;; Hy uses same sexp concepts
(defclass ColoredSExpr []
  "S-expression with semantic color annotations")
  
(defn acset-to-colored-sexpr [acset]
  "Convert ThreadACSet to Colored S-expression tree")

colored_sexp_acset.jl

# Inverse operation: Sexp → ACSet graph
function sexp_to_graph(sexp::ColoredSexp)::ColoredSexpData
    data = ColoredSexpData()
    _add_sexp!(data, sexp, nothing, 0)
    data
end

Justfile Recipes

# Run demo
lispsyntax-demo:
    julia --project=. -e 'include("lib/lispsyntax_acset_bridge.jl"); LispSyntaxAcsetBridge.demo()'

# Test roundtrip parsing
lispsyntax-test:
    julia --project=. -e '
    include("lib/lispsyntax_acset_bridge.jl")
    using .LispSyntaxAcsetBridge
    @assert verify_parse_roundtrip("(a (b c) d)")
    println("✓ Parse roundtrip OK")
    '

File Locations

• Bridge implementation: lib/lispsyntax_acset_bridge.jl
• Colored ACSet: lib/colored_sexp_acset.jl
• Hy integration: lib/thread_relational_hyjax.hy
• Clojure integration: src/sicp/colored-sexp.clj

Specter-Style Navigation (Zero-Overhead)

NEW 2025-12-22: Integrated Specter-style bidirectional navigation with Julia-specific optimizations achieving 93-113x speedup over CPS-based implementation.

Benchmark Results (Chairmarks)

Operation	Hand-Written	Original CPS	Optimized	Ratio
Select evens (n=1000)	423.8 ns	52.58 μs	561.6 ns	1.3x
Transform evens	354.9 ns	40.04 μs	354.2 ns	1.0x
comp_navs allocation	-	7.8 ns	0.5 ns	15.7x

Key Optimizations

1. Tuple paths vs Vector{Navigator} → type stability, 0 allocs
2. Functor structs vs closures → no capture, fully inlinable
3. @inline annotations → aggressive hot path inlining
4. Fused ALL+pred → single traversal for filter operations

Correct-by-Construction via 3-MATCH

Path caching follows 3-MATCH gadget principles:

• Local constraint: Path types correct at compile time
• Global correctness: Cached paths guaranteed correct
• GF(3) conservation: Tuple → TupleNav → Result preserves sum

# Correct-by-construction path caching
compiled_path = TupleNav((ALL, pred(iseven)))  # Type-stable, 0 allocs
result = nav_select(compiled_path, data, IDENTITY)  # Guaranteed correct

Files

• lib/specter_optimized.jl - Zero-overhead implementation
• lib/specter_chairmarks_world.jl - Chairmarks benchmarks
• SPECTER_OPTIMIZATION_RESULTS.md - Full benchmark report

See Also

• LispSyntax.jl - Clojure-like Lisp in Julia
• ppx_sexp_conv - OCaml S-expression PPX
• sexplib - OCaml S-expression library
• acsets-algebraic-databases skill - ACSet foundations
• gay-mcp skill - Deterministic coloring
• three-match skill - Correct-by-construction caching