lispsyntax-acset

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)