motoko (moc)

• Emit new ICP metadata custom section 'motoko:compiler' with compiler release or revision in UTF8 (e.g. "0.6.21"). Default is icp:private (#3091).
• Generalized import supporting pattern matching and selective field imports (#3076).
• Fix: insert critical overflow checks preventing rare heap corruptions
  in out-of-memory allocation and stable variable serialization (#3077).
• Implement support for 128-bit Cycles-API (#3042).

motoko-base

• ExperimentalInternetComputer library, exposing low-level, binary call function (a.k.a. "raw calls") (dfinity/motoko-base#334, Motoko #3806).
• Principal.fromBlob added (dfinity/motoko-base#331).

motoko

• Implement support for heartbeat system methods (thanks to ninegua) (#2971)

motoko-base

• Add Iter.filter : <A>(Iter<A>, A -> Bool) -> Iter<A> (thanks to jzxchiang1) (dfinity/motoko-base#328).

motoko-base

• Fixed a bug in the RBTree.size() method.

moc

• Add runtime support for low-level, direct access to 64-bit IC stable memory, including documentation.
• Add compiler flag --max-stable-pages <n> to cap any use of ExperimentalStableMemory.mo (see below), while reserving space for stable variables.
  Defaults to 65536 (4GiB).

motoko-base

• (Officially) add ExperimentalStableMemory.mo library, exposing 64-bit IC stable memory

BREAKING CHANGE (Minor):
The previously available (but unadvertised) ExperimentalStableMemory.mo used
Nat32 offsets. This one uses Nat64 offsets to (eventually) provide access to more address space.

The compiler now embeds the existing Candid interface and new
stable signature of a canister in additional Wasm custom sections,
to be selectively exposed by the IC, and to be used by tools such as dfx
to verify upgrade compatibility (see extended documentation).

New compiler options:

• --public-metadata <name>: emit ICP custom section <name> (candid:args or candid:service or motoko:stable-types) as public (default is private)
• --stable-types: emit signature of stable types to .most file
• --stable-compatible <pre> <post>: test upgrade compatibility between stable-type signatures <pre> and <post>

A Motoko canister upgrade is safe provided:

• the canister's Candid interface evolves to a Candid subtype; and
• the canister's Motoko stable signature evolves to a stable-compatible one.

(Candid subtyping can be verified using tool didc available at:
https://github.com/dfinity/candid.)

BREAKING CHANGE (Minor):
Tightened typing for type-annotated patterns (including function parameters)
to prevent some cases of unintended and counter-intuitive type propagation.

This may break some rare programs that were accidentally relying on that
propagation. For example, the indexing xs[i] in the following snippet
happend to type-check before, because i was given the more precise
type Nat (inferred from run's parameter type), regardless of the
overly liberal declaration as an Int:

func run(f : Nat -> Text) {...};
let xs = ["a", "b", "c"];
run(func(i : Int) { xs[i] });

This no longer works, i has to be declared as Nat (or the type omitted).

If you encounter such cases, please adjust the type annotation.

Improved garbage collection scheduling

Miscellaneous performance improvements

• code generation for for-loops over arrays has improved
• slightly sped up Int equality comparisons

for loops over arrays are now converted to more efficient
index-based iteration (#2831). This can result in significant cycle
savings for tight loops, as well as slightly less memory usage.

Add type union and intersection. The type expression

T and U

produces the greatest lower bound of types T and U, that is,
the greatest type that is a subtype of both. Dually,

T or U

produces the least upper bound of types T and U, that is,
the smallest type that is a supertype of both.

One use case of the former is "extending" an existing object type:

type Person = {name : Text; address : Text};
type Manager = Person and {underlings : [Person]};

Similarly, the latter can be used to "extend" a variant type:

type Workday = {#mon; #tue; #wed; #thu; #fri};
type Weekday = Workday or {#sat; #sun};