beta.20 — Circom frontend
The headline release: Achronyme compiles .circom files end-to-end with soundness diagnostics circom itself does not provide.
Achronyme 0.1.0-beta.20 ships the Circom frontend: .circom files flow through the same pipeline as native .ach circuits, with compile-time soundness checks the reference circom compiler does not perform. This page is the two-minute version — the full changelog entry lives in the Changelog.
TL;DR
ach circom file.circom --provecompiles and proves a circom circuit end-to-end.- Constraint counts match or beat circom’s most aggressive optimizer (O2) on every benchmarked circomlib template (Num2Bits, LessThan, MiMCSponge, Poseidon, Pedersen, EscalarMulAny, and more).
- E100 + W101 catch under-constrained signals at compile time — the #1 source of ZK bugs, which the circom compiler does not detect.
- Three ways to reach Circom code: full absorption (
import circuit), selective templates (import { T } from), or namespaced library (import ... as P). See Circom Interop Overview. [circom]section inachronyme.tomlcentralizes library search paths — no more-lon every invocation. See Project Configuration.
Why it matters
The vast majority of production ZK applications today depend on circomlib — Poseidon, MiMC, EdDSA, BabyJubjub, Num2Bits, bit comparators. Until beta.20, using any of those from Achronyme meant rewriting them in .ach. Now you import the original .circom source and Achronyme’s pipeline compiles it:
parse → constraint analysis → lower to ProveIR → optimize → R1CS / Plonkish → Groth16The compiled output is snarkjs-compatible (.r1cs + .wtns) and the Solidity verifier generator works for circom-sourced circuits exactly as it does for native Achronyme.
The headline soundness checks
Circom’s own compiler does not flag unconstrained signals. Achronyme does:
- E100 — hard error when a signal assigned with
<--has no===anywhere. This is the classic bug behind virtually every circomlib audit finding: a witness hint without a corresponding constraint lets a malicious prover write anything. - W101 — warning when a
signal input/signal outputnever participates in a constraint. Subtle and very common; often shipped to mainnet. - W102 / W103 — warnings on weaker variants (signal assigned but not verified against an expression).
The full list, with rendered examples, lives in Diagnostics.
Constraint counts vs circom O2
The benchmark is r1cs_optimization_benchmark in circom/tests/e2e.rs. Achronyme’s O1 pass (constant propagation + linear-combination folding + DEDUCE Gaussian elimination) matches or beats circom’s best setting on every template we have E2E-tested:
| Template | Achronyme O1 | circom O2 | Result |
|---|---|---|---|
Num2Bits(8) | 9 | 17 | −8 |
LessThan(8) | 10 | 20 | −10 |
MiMCSponge(2, 220, 1) | 1317 | 1320 | −3 |
IsZero() | 2 | 2 | tie |
Poseidon(2) | 240 | 240 | tie |
Pedersen(8) | 13 | 13 | tie |
EscalarMulFix(253) | 11 | 11 | tie |
EscalarMulAny(254) | 2310 | 2310 | tie |
End-to-end Groth16 proof verification has been done on-chain for Num2Bits, IsZero, LessThan, Poseidon(2), and EscalarMulAny(254). The full compatibility list is in Limitations and Roadmap.
What changed under the hood
- New 11th workspace crate:
circom/— hand-written Pratt parser, constraint analyzer, lowering pipeline (21 modules), witness evaluator, Groth16 E2E. - New diagnostics codes: E100-E102 (constraint soundness), W101-W103 (warning on unverified signals), E200-E211 (lowering), E300-E306 (parser).
- New opcodes / infrastructure:
CallCircomTemplate(VM-mode calls),TAG_CIRCOM_HANDLE,CircomWitnessHandlertrait,CircomLibraryHandletrait,CircomCallabledispatch. - Compile-time arithmetic migrated from
i64to BigVal (256-bit two’s complement), so templates that compute1 << 128(likeCompConstant) work correctly. - Dynamic loop bounds (
for i in 0..n+1), component arrays (component muls[n]), 2-D array variables (var M[t][t]), function-keyword compile-time evaluator. - R1CS optimizer v2: frequency heuristic, tautological linear removal, zero-product handling, plus DEDUCE Gaussian elimination with field-folding constant propagation.
Upgrading from beta.19
No breaking changes for existing .ach code. prove {} blocks still work. Existing .achb bytecode compiled under beta.19 requires a recompile (ProveIR format bumped to v5).
If you were using ach circom in a pre-release branch, [circom].libs now lives in achronyme.toml at the project root and takes relative paths.
Where to go next
- Circom Interop Overview — the why + how, three-minute read.
- Circuit Mode — full-circuit absorption workflow.
- Importing Templates — selective and namespaced imports.
- Diagnostics — every error and warning with rendered output.
- Limitations and Roadmap — what works today, what’s next.
- Changelog — the full, commit-level release notes.