Optimize Effect Schema and add experimental JIT and AOT compilers

[gcanti]

Summary

Optimizes the Effect Schema interpreter and adds experimental JIT and AOT compilers. All three modes use the existing SchemaParser APIs and remain composable.

Usage

Enable lazy JIT compilation for the application:

import "effect/unstable/schema/SchemaJITCompiler/enable"

Or enable one AST and its dependencies:

import * as SchemaJITCompiler from "effect/unstable/schema/SchemaJITCompiler"

SchemaJITCompiler.enable(User.ast)

Generate and install AOT decoders:

import * as SchemaAOTCompilerBuild from "effect/unstable/schema/SchemaAOTCompiler/Build"

SchemaAOTCompilerBuild.build({
  modules: import.meta.glob("./schemas/*.ts"),
  baseUrl: import.meta.url,
  outFile: "./generated/schema-aot.js"
})

Import the generated module at application startup. Decoding is included by default; encode, is, and make roots are opt-in. SchemaAOTCompiler.compile(targets) provides the lower-level source-generation API.

Design

The interpreter, JIT, AOT, and manually installed decoders share one registry keyed by AST identity. JIT compiles lazily and falls back to the interpreter when dynamic function construction is unavailable or compilation fails. AOT uses the same code generator without new Function, emits only the requested operations and their transitive dependencies, and shares decoder factories that generate identical code. Transformations and middleware run once.

Performance

Median time per operation on Node 24.12.0, V8 13.6, Apple M3. Measurements use five isolated rounds, 100 ms warmup, 300 ms measurement, and shared batch sizes. Effect uses public SchemaParser APIs. Valibot 1.5.0 uses parse and is. Zod 4.6.2 uses parse and validate with { jitless: true }, or z.compile(schema, { strict: true }). Lower is better. Bold values are within 5% of the fastest result in each row.

Interpreted

Case	Main interpreter	Branch interpreter	Valibot	Zod jitless
Moltar parseSafe, valid	363.9 ns	326.3 ns	353.7 ns	400.3 ns
Moltar parseSafe, invalid	3.05 µs	3.06 µs	3.51 µs	4.79 µs
Moltar assertLoose, valid	332.3 ns	326.8 ns	427.3 ns	469.9 ns
Moltar assertLoose, invalid	129.2 ns	118.4 ns	57.7 ns	96.3 ns
Array of 32 Structs	3.15 µs	3.11 µs	3.16 µs	3.79 µs
Record of 32 Structs	3.81 µs	3.81 µs	3.81 µs	5.83 µs
Discriminated Union, 8 members	91.7 ns	93.8 ns	397.4 ns	1.29 µs
Struct with 32 transformations	2.00 µs	1.52 µs	1.52 µs	1.77 µs
Construct 32 defaulted fields	2.17 µs	868.1 ns	1.06 µs	1.48 µs
Construct Array of 32 Structs	3.15 µs	3.11 µs	2.99 µs	3.73 µs

Compiled

Case	JIT	AOT	Zod compile
Moltar parseSafe, valid	5.55 ns	5.51 ns	5.33 ns
Moltar parseSafe, invalid	3.39 µs	3.44 µs	4.42 µs
Moltar assertLoose, valid	2.95 ns	2.93 ns	3.46 ns
Moltar assertLoose, invalid	1.04 ns	1.04 ns	1.34 ns
Array of 32 Structs	132.6 ns	129.9 ns	127.6 ns
Record of 32 Structs	594.2 ns	594.3 ns	1.51 µs
Discriminated Union, 8 members	15.5 ns	15.7 ns	29.6 ns
Struct with 32 transformations	154.2 ns	155.4 ns	204.3 ns
Construct 32 defaulted fields	356.8 ns	358.1 ns	481.8 ns
Construct Array of 32 Structs	133.9 ns	145.0 ns	128.6 ns

Paired runs against main found no interpreter regressions. The 32-field transformation improved by 19.5%, and the invalid Moltar guard improved by 8%.

The construction rows are reference comparisons. Effect uses SchemaParser.make, while Valibot and Zod parse equivalent schemas because they have no separate construction API.

Zod compilation has no comparable result for trailing-rest tuples, strict oneOf, middleware, or recursive schemas.

Resource costs

Incremental costs are median per-schema slopes between 100 and 500 distinct schemas across five fresh-process rounds. Lower is better. Retained heap includes schemas, public parsers, and their runtime state. Fixed module imports and fixture inputs are excluded. Importing the JIT compiler retains about 118 KiB of additional fixed heap in this source-tree setup.

Preparation CPU includes adapter creation and the first call. AOT also includes importing and installing the generated module, but excludes build-time generation. Generated AOT source is operation-specific: 2.07 KiB/schema for Struct decode, 0.62 KiB/schema for guards, 2.90 KiB/schema for an Array of 32 Structs, 28.24 KiB/schema for 32 transformations, and 11.67 KiB/schema for 32-default construction. Sharing identical decoder factories and omitting unused dependency fast paths reduce an eight-member discriminated Union from 17.72 to 5.46 KiB/schema.

Retained JavaScript heap

Case	Effect JIT	Effect AOT	Zod compile
Struct	5.33 KiB/schema	7.90 KiB/schema	9.37 KiB/schema
Struct invalid	10.66 KiB/schema	11.63 KiB/schema	16.25 KiB/schema
Struct guard	5.00 KiB/schema	5.59 KiB/schema	9.13 KiB/schema
Array of 32 Structs	9.82 KiB/schema	14.47 KiB/schema	12.01 KiB/schema
Discriminated Union	27.90 KiB/schema	38.54 KiB/schema	47.97 KiB/schema
32 transformations	81.56 KiB/schema	81.11 KiB/schema	101.37 KiB/schema
Construct 32 defaults	72.00 KiB/schema	73.96 KiB/schema	123.30 KiB/schema

Runtime preparation CPU

Case	Effect JIT	Effect AOT	Zod compile
Struct	31.7 µs/schema	39.2 µs/schema	55.6 µs/schema
Struct invalid	103.4 µs/schema	83.4 µs/schema	156.9 µs/schema
Struct guard	28.0 µs/schema	24.1 µs/schema	52.2 µs/schema
Array of 32 Structs	66.2 µs/schema	82.9 µs/schema	88.6 µs/schema
Discriminated Union	96.1 µs/schema	126.2 µs/schema	234.1 µs/schema
32 transformations	940.0 µs/schema	760.8 µs/schema	371.0 µs/schema
Construct 32 defaults	404.3 µs/schema	373.0 µs/schema	654.9 µs/schema

Bundle size

Consumer	Minified + gzip	Delta
Main, no compiler	17.55 KB	baseline
Branch, no compiler	17.84 KB	+0.29 KB
Branch with JIT	23.85 KB	+6.01 KB
Branch with AOT	19.77 KB	+1.93 KB

Across 15 stable Schema fixtures, the branch adds 0.25 to 0.44 KB gzip, averaging 0.33 KB.

Constraints

• Install JIT or AOT before the first parser execution that should use it.
• Rebuild AOT output after changing Schema definitions or the Effect version.
• AOT generation loads the selected application modules at build time.

Detailed architecture, compatibility, memory, and benchmark notes are in packages/effect/SCHEMA.md.

Verification

• Full Schema suite
• JIT and AOT integration tests
• AOT execution without dynamic function construction
• AOT builder output through public SchemaParser APIs
• Typecheck, compiler type tests, lint, and circular-dependency checks

[changeset-bot]

🦋 Changeset detected

Latest commit: 3cb8c6c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 30 packages

Name	Type
effect	Patch
@effect/opentelemetry	Patch
@effect/vitest	Patch
@effect/ai-anthropic	Patch
@effect/ai-openai-compat	Patch
@effect/ai-openai	Patch
@effect/ai-openrouter	Patch
@effect/atom-react	Patch
@effect/atom-solid	Patch
@effect/atom-vue	Patch
@effect/platform-browser	Patch
@effect/platform-bun	Patch
@effect/platform-deno	Patch
@effect/platform-node-shared	Patch
@effect/platform-node	Patch
@effect/sql-clickhouse	Patch
@effect/sql-d1	Patch
@effect/sql-libsql	Patch
@effect/sql-mssql	Patch
@effect/sql-mysql2	Patch
@effect/sql-pg	Patch
@effect/sql-pglite	Patch
@effect/sql-sqlite-bun	Patch
@effect/sql-sqlite-do	Patch
@effect/sql-sqlite-node	Patch
@effect/sql-sqlite-react-native	Patch
@effect/sql-sqlite-wasm	Patch
@effect/docgen	Patch
@effect/doctest	Patch
@effect/openapi-generator	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

Bundle Size Analysis

Generated from PR build output; treat the content below as untrusted.

File Name	Current Size	Previous Size	Difference
arbitrary-combinators.ts	35.00 KB	34.58 KB	+0.42 KB (+1.21%)
basic.ts	6.87 KB	6.87 KB	0.00 KB (0.00%)
batching.ts	9.95 KB	9.95 KB	0.00 KB (0.00%)
brand.ts	6.45 KB	6.45 KB	0.00 KB (0.00%)
cache.ts	10.77 KB	10.77 KB	0.00 KB (0.00%)
config.ts	21.83 KB	21.51 KB	+0.32 KB (+1.50%)
differ.ts	20.67 KB	20.32 KB	+0.35 KB (+1.72%)
http-client.ts	21.93 KB	21.93 KB	0.00 KB (0.00%)
http-router.ts	36.92 KB	36.92 KB	0.00 KB (0.00%)
logger.ts	10.88 KB	10.88 KB	0.00 KB (0.00%)
metric.ts	9.02 KB	9.02 KB	0.00 KB (0.00%)
optic.ts	6.70 KB	6.70 KB	0.00 KB (0.00%)
pubsub.ts	15.10 KB	15.10 KB	0.00 KB (0.00%)
queue.ts	11.85 KB	11.85 KB	0.00 KB (0.00%)
schedule.ts	10.96 KB	10.96 KB	0.00 KB (0.00%)
schema-binary.ts	39.82 KB	39.51 KB	+0.31 KB (+0.78%)
schema-class.ts	20.38 KB	20.06 KB	+0.32 KB (+1.61%)
schema-fromJsonSchemaDocument.ts	31.18 KB	30.93 KB	+0.25 KB (+0.80%)
schema-representation-roundtrip.ts	26.60 KB	26.34 KB	+0.26 KB (+0.98%)
schema-string-transformation.ts	13.94 KB	13.63 KB	+0.31 KB (+2.26%)
schema-string.ts	11.55 KB	11.12 KB	+0.43 KB (+3.89%)
schema-template-literal.ts	15.69 KB	15.41 KB	+0.27 KB (+1.78%)
schema-toArbitrary.ts	34.55 KB	34.10 KB	+0.44 KB (+1.30%)
schema-toCodeDocument.ts	24.84 KB	24.56 KB	+0.28 KB (+1.14%)
schema-toCodecJson.ts	19.61 KB	19.27 KB	+0.34 KB (+1.76%)
schema-toEquivalence.ts	19.75 KB	19.38 KB	+0.37 KB (+1.92%)
schema-toFormatter.ts	19.85 KB	19.49 KB	+0.36 KB (+1.85%)
schema-toJsonSchemaDocument.ts	24.15 KB	23.77 KB	+0.38 KB (+1.59%)
schema-toRepresentation.ts	19.89 KB	19.54 KB	+0.35 KB (+1.80%)
schema.ts	19.59 KB	19.27 KB	+0.32 KB (+1.66%)
stm.ts	12.80 KB	12.80 KB	0.00 KB (0.00%)
stream.ts	9.83 KB	9.83 KB	0.00 KB (0.00%)