feat: Single-word `Array` abstraction #2203

mmagician · 2025-12-19T15:31:51Z

We eventually want to have double-word arrays & double-word queues. Once we agreed on the structure and where the files live, it's going to be trivial to extend to double-word array. A queue will require an extra storage slot to hold the metadata, though.

Features:

add a simple wrapper over storage map, s.t. the map keys are [index, 0, 0, 0]
export procedures set(slot_id_prefix: felt, slot_id_suffix: felt, index: Felt, VALUE: Word) -> OLD_VALUE: Word & get(slot_id_prefix: felt, slot_id_suffix: felt, index: Felt) -> VALUE: Word
tests that show how other account components have an easy interface for operating on the array

Usage:

use miden::core::word
use miden::standards::data_structures::array

const ARRAY_SLOT = word("test::array::data")

#! Wrapper for array::get that uses exec internally.
#! Inputs:  [index, pad(15)]
#! Outputs: [VALUE, pad(12)]
pub proc test_get
    push.ARRAY_SLOT[0..2]
    exec.array::get
end

#! Wrapper for array::set that uses exec internally.
#! Inputs:  [index, VALUE, pad(11)]
#! Outputs: [OLD_VALUE, pad(12)]
pub proc test_set
    push.ARRAY_SLOT[0..2]
    exec.array::set
end

let data_slot = StorageSlotName::new("test::array::data").unwrap();

// Create the wrapper account component
let wrapper_component = AccountComponent::new(
    wrapper_library.clone(),
    vec![StorageSlot::with_map(
        data_slot.clone(),
        StorageMap::with_entries([(
            Word::from([Felt::ZERO, Felt::ZERO, Felt::ZERO, Felt::ZERO]),
            Word::from([42u32, 42, 42, 42]),
        )])?,
    )],
)?
.with_supports_all_types();

mmagician · 2025-12-19T17:18:43Z

@copilot add change log entry for this PR 2203

Copilot · 2025-12-19T17:18:56Z

@mmagician I've opened a new pull request, #2204, to work on those changes. Once the pull request is ready, I'll request review from you.

Copilot

Pull request overview

This PR introduces a single-word Array account component that provides a simple, reusable array data structure for Miden accounts. The implementation wraps a StorageMap where array indices are mapped to keys of the form [index, 0, 0, 0].

Key changes:

Added Array struct with methods for creating arrays with initial elements or from slices
Implemented MASM procedures (get and set) for array access with configurable storage slots
Added comprehensive unit tests and integration tests demonstrating the component's usage

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
`crates/miden-standards/src/account/array.rs`	Core implementation of the Array component with constructors, MASM generation, and conversion to AccountComponent
`crates/miden-standards/asm/account_components/array.masm`	MASM template defining `get` and `set` procedures for array operations
`crates/miden-standards/src/account/mod.rs`	Adds array module to the account components public API
`crates/miden-testing/src/kernel_tests/tx/test_array.rs`	Integration test verifying get/set operations work correctly in transaction context
`crates/miden-testing/src/kernel_tests/tx/mod.rs`	Includes the new test module
`CHANGELOG.md`	Documents the addition of the Array component

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crates/miden-standards/asm/account_components/array.masm

crates/miden-standards/src/account/array.rs

Copilot

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

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crates/miden-standards/asm/account_components/array.masm

crates/miden-standards/asm/standards/data_structures/array.masm

crates/miden-standards/asm/account_components/array.masm

partylikeits1983 · 2026-01-05T15:31:15Z

Looks great! This is a great feature!

When reviewing the implementation, it reminded me of this issue for KEY => vec![] issue I opened: #2085

crates/miden-standards/asm/account_components/array.masm

Fumuran

Looks good! Aside from the decision of whether we need to make this component a utility, I have just a small style nit inline.

crates/miden-standards/asm/standards/data_structures/array.masm

chore: simplify test chore: be explicit about padding

* Initial plan * chore: add changelog entry for PR 2203 Co-authored-by: mmagician <8402446+mmagician@users.noreply.github.com> --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: mmagician <8402446+mmagician@users.noreply.github.com>

Co-authored-by: Andrey Khmuro <andrey@polygon.technology>

chore: remove component code

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

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crates/miden-testing/src/kernel_tests/tx/test_array.rs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

PhilippGackstatter

Looks good to me! Sorry for the late review, it slipped through my notifications.

PhilippGackstatter · 2026-01-22T08:22:07Z

crates/miden-testing/src/kernel_tests/tx/test_array.rs

+    let wrapper_component_code = format!(
+        r#"
+        use miden::core::word
+        use miden::standards::data_structures::array


If we end up introducing a "storage array" (#2176 or #383) next to the "storage map", naming this "array" may be confusing. First question is whether we would keep this data structure if we'd add a protocol-level "array" and if so, maybe it should be called smt_array or something to differentiate it from "storage array".

Nit: I think miden::standards::(smt_)array would also be sufficient (motivation).

First question is whether we would keep this data structure if we'd add a protocol-level "array"

no, probably we'd not keep both around, but for now we need an array concept (really the double-word array) for the AggLayer integration.

I would avoid smt_array, because the underlying data structure should not matter to the user (as long as this is the only array impl. we have).

So I'd leave this as-if for now, and remove if/when storage arrays land. Do you think we could merge with the current naming & module placement?

mmagician force-pushed the mmagician-array-via-map branch from 505aa25 to 5479b77 Compare December 19, 2025 15:35

Copilot AI mentioned this pull request Dec 19, 2025

chore: add changelog entry for Array component #2204

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mmagician mentioned this pull request Jan 14, 2026

AggLayer: implement verify_leaf #2277

Open

mmagician and others added 8 commits January 17, 2026 10:02

feat: working array

6f03672

chore: simplify test chore: be explicit about padding

fix: set_map_item no longer returns old root

c1c788d

chore: change Try to TryFrom for AccountComponent

05b5234

chore: correct the docs

aa50de3

chore: masm doc corrections

d04e396

chore: use BeWord instead of Word

17d96bf

chore: adjust masm comment about max len

2d34da0

mmagician and others added 2 commits January 17, 2026 10:04

Update crates/miden-standards/asm/account_components/array.masm

cff5982

Co-authored-by: Andrey Khmuro <andrey@polygon.technology>

chore: turn array into utility

6bd6069

chore: remove component code

mmagician force-pushed the mmagician-array-via-map branch from 34ccf83 to 6bd6069 Compare January 17, 2026 10:04

mmagician added 3 commits January 17, 2026 10:23

chore: lint, simplify test & comments

3ff3c49

chore: remove unnecessary comments

0c37ba3

chore: remove duplicated changelog entry

ab2ca4d

mmagician changed the title ~~feat: Single-word Array component~~ feat: Single-word Array abstraction Jan 17, 2026

mmagician requested a review from bobbinth January 17, 2026 10:53

mmagician mentioned this pull request Jan 17, 2026

feat: double-word Array abstraction #2299

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partylikeits1983 approved these changes Jan 21, 2026

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feat: Single-word Array abstraction #2203

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feat: Single-word `Array` abstraction #2203

feat: Single-word `Array` abstraction #2203

mmagician commented Dec 19, 2025 •

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