Changelog.md

Motoko compiler changelog

0.13.3 (2024-11-13)

• motoko (moc)

  • typing: suggest conversions between primitive types from imported libraries and, with --ai-errors, all available package libraries (#4747).

• motoko-base

  • Add modules OrderedMap and OrderedSet to replace RBTree with improved functionality, performance and ergonomics avoiding the need for preupgrade hooks (thanks to Serokell) (#662).

0.13.2 (2024-10-18)

• motoko (moc)

  • Made the actor's self identifier available in the toplevel block. This also allows using functions that refer to self from the initialiser (e.g. calls to setTimer) (#4720).

  • bugfix: actor <exp> now correctly performs definedness tracking (#4731).

0.13.1 (2024-10-07)

• motoko (moc)

  • Improved error messages for unbound identifiers and fields that avoid reporting large types and use an edit-distance based metric to suggest alternatives (#4720).

  • Flag --ai-errors to tailor error messages to AI clients (#4720).

  • Compilation units containing leading type definitions are now rejected with an improved error message (#4714).

  • bugfix: floatToInt64 now behaves correctly in the interpreter too (#4712).

0.13.0 (2024-09-17)

• motoko (moc)

  • Added a new primitive cyclesBurn : <system> Nat -> Nat for burning the canister's cycles programmatically (#4690).

  • For beta testing: Support enhanced orthogonal persistence, enabled with new moc flag --enhanced-orthogonal-persistence (#4193).

    This implements scalable and efficient orthogonal persistence (stable variables) for Motoko:

    • The Wasm main memory (heap) is retained on upgrade with new program versions directly picking up this state.
    • The Wasm main memory has been extended to 64-bit to scale as large as stable memory in the future.
    • The runtime system checks that data changes of new program versions are compatible with the old state.

    Implications:

    • Upgrades become extremely fast, only depending on the number of types, not on the number of heap objects.
    • Upgrades will no longer hit the IC instruction limit, even for maximum heap usage.
    • The change to 64-bit increases the memory demand on the heap, in worst case by a factor of two.
    • For step-wise release handling, the IC initially only offers a limited capacity of the 64-bit space (e.g. 4GB or 6GB), that will be gradually increased in future to the capacity of stable memory.
    • There is moderate performance regression of around 10% for normal execution due to combined related features (precise tagging, change to incremental GC, and handling of compile-time-known data).
    • The garbage collector is fixed to incremental GC and cannot be chosen.
    • Float.format(#hex prec, x) is no longer supported (expected to be very rarely used in practice).
    • The debug print format of NaN changes (originally nan).

    To activate enhanced orthogonal persistence under dfx, the following command-line argument needs to be specified in dfx.json:

    ...
      "type" : "motoko"
      ...
      "args" : "--enhanced-orthogonal-persistence"
    ...
    

    BREAKING CHANGE (Minor): changes some aspects of Float formatting.

    For more information, see:

    • The Motoko design documentation design/OrthogonalPersistence.md
    • The Motoko user documentation doc/md/canister-maintenance/upgrades.md.

  • Candid decoding: impose an upper limit on the number of values decoded or skipped in a single candid payload, as a linear function, max_values, of binary payload size.

      max_values(blob) = (blob.size() * numerator)/denominator + bias
    

    The current default settings are {numerator = 1; denominator = 1; bias = 1024 }, allowing a maximum of 1024 values plus one additional value per byte in the payload.

    While hopefully not required, the constant factors can be read/modified using system functions:

    • Prim.setCandidLimits: <system>{numerator : Nat32; denominator : Nat32; bias : Nat32 } -> ()
    • Prim.getCandidLimits: <system>() -> {numerator : Nat32; denominator : Nat32; bias : Nat32 }

0.12.1 (2024-08-08)

• motoko (moc)

  • Added a new command-line flag --print-source-on-error to print source code context on error (#4650).

  • debugging: __motoko_runtime_information() as privileged query for runtime statistics (#4635).

    Exposing a privileged system-level query function __motoko_runtime_information() that reports the current runtime statistics of the canister, such as the heap size, the total number of allocated objects, the total amount of reclaimed memory and more. This is useful because several statistics of the reported information cannot be inspected on the IC replica dashboard as they are internal to the Motoko runtime system. This query is only authorized to the canister controllers and self-calls of the canister.

    __motoko_runtime_information : () -> {
        compilerVersion : Text;
        rtsVersion : Text;
        garbageCollector : Text;
        sanityChecks : Nat;
        memorySize : Nat;
        heapSize : Nat;
        totalAllocation : Nat;
        reclaimed : Nat;
        maxLiveSize : Nat;
        stableMemorySize : Nat;
        logicalStableMemorySize : Nat;
        maxStackSize : Nat;
        callbackTableCount : Nat;
        callbackTableSize : Nat;
    }

• motoko-base

  • Added Iter.concat function (thanks to AndyGura) (dfinity/motoko-base⁠#650).

0.12.0 (2024-07-26)

• motoko (moc)

  • feat: finally clauses for try expressions (#4507).

    A trailing finally clause to try/catch expressions facilitates structured resource deallocation (e.g. acquired locks, etc.) and similar cleanups in the presence of control-flow expressions (return, break, continue, throw). Additionally, in presence of finally the catch clause becomes optional and and any uncaught error from the try block will be propagated, after executing the finally block.

    Note: finally-expressions that are in scope will be executed even if an execution path following an await-expression traps. This feature, formerly not available in Motoko, allows programmers to implement cleanups even in the presence of traps. For trapping execution paths prior to any await, the replica-provided state roll-back mechanism ensures that no cleanup is required.

    The relevant security best practices are accessible at https://internetcomputer.org/docs/current/developer-docs/security/security-best-practices/inter-canister-calls#recommendation

    BREAKING CHANGE (Minor): finally is now a reserved keyword, programs using this identifier will break.

  • bugfix: mo-doc will now generate correct entries for public variables (#4626).

0.11.3 (2024-07-16)

• motoko (moc)

  • feat: motoko-san contributions by Serokell. Now able to verify some simple but non-trivial actors (thanks to the entire Serokell team) (#4500).

  • bugfix: Corrects the interpreter (and compiler) to recognise certain type parameters as callable function types (#4617).

0.11.2 (2024-07-06)

• motoko (moc)

  • deprecation: Deprecate the use of base library's ExperimentalStableMemory (ESM) (#4573). New moc flag --experimental-stable-memory <n> controls the level of deprecation:

    • n < 0: error on use of stable memory primitives.
    • n = 0: warn on use of stable memory primitives.
    • n > 1: warning-less use of stable memory primitives (for legacy applications). Users of ESM should consider migrating their code to use isolated regions (library Region.mo) instead.

  • bugfix: Fix the detection of unused declarations in switch and catch alternatives (#4560).

  • improvement: Only warn on unused identifiers if type checking is error-free (#4561).

0.11.1 (2024-03-15)

• motoko (moc)

  • feat: Custom error message for unused, punned field bindings (#4454).

  • feat: Don't report top-level identifiers as unused (#4452).

  • bugfix: Declaring <system, ...> capability on a class enables system capabilities in its body (#4449).

  • bugfix: Fix crash compiling actor reference containing an await (#4418, #4450).

  • bugfix: Fix crash when compiling with flag --experimental-rtti (#4434).

0.11.0 (2024-03-05)

• motoko (moc)

  • Warn on detection of unused identifiers (code M0194) (#4377).

    • By design, warnings are not emitted for code imported from a package.
    • A warning can be suppressed by replacing the identifier entirely by a wildcard _, or by prefixing it with an _, e.g. replace x by _x.

    Limitations: recursive and mutually recursive definitions are considered used, even if never referenced outside the recursive definition.

  • Remove __get_candid_interface_tmp_hack endpoint. Candid interface is already stored as canister metadata, this temporary endpoint is redundant, thus removed. (#4386)

  • Improved capability system, introducing a synchronous (system) capability (#4406).

    actor initialisation body, pre/postupgrade hooks, async function bodies (and blocks) possess this capability. Functions (and classes) can demand it by prepending system to the type argument list. The capability can be forwarded in calls by mentioning <system, …> in the instantiation parameter list.

    BREAKING CHANGE (Minor): A few built-in functions have been marked with demand for the system capability. In order to call these, the full call hierarchy needs to be adapted to pass the system capability.

  • Introduced the feature for precise tagging of scalar values (#4369).

    Controlled by flag --experimental-rtti (off by default). Minor performance changes for arithmetic expected. We advise to only turn on the feature for testing, as currently no productive upsides exist (though future improvements will depend on it), and performance of arithmetic will degrade somewhat. See the PR for the whole picture.

• motoko-base

  • Added Option.equal function (thanks to ByronBecker) (dfinity/motoko-base⁠#615).

0.10.4 (2024-01-10)

• motoko (moc)

  • Officializing the new incremental garbage collector after a successful beta testing phase. The incremental GC can be enabled by the moc flag --incremental-gc (#3837) and is designed to scale for large program heap sizes.

    Note: While resolving scalability issues with regard to the instruction limit of the GC work, it is now possible to hit other scalability limits:

    • Out of memory: A program can run out of memory if it fills the entire memory space with live objects.
    • Upgrade limits: When using stable variables, the current mechanism of serialization and deserialization to and from stable memory can exceed the instruction limit or run out of memory.

    Recommendations:

    • Test the upgrade: Thoroughly test the upgrade mechanism for different data volumes and heap sizes and conservatively determine the amount of stable data that is supported when upgrading the program.
    • Monitor the heap size: Monitor the memory and heap size (Prim.rts_memory_size() and Prim.rts_heap_size()) of the application in production.
    • Limit the heap size: Implement a custom limit in the application to keep the heap size and data volume below the scalability limit that has been determined during testing, in particular for the upgrade mechanism.
    • Avoid large allocations per message: Avoid large allocations of 100 MB or more per message, but rather distribute larger allocations across multiple messages. Large allocations per message extend the duration of the GC increment. Moreover, memory pressure may occur because the GC has a higher reclamation latency than a classical stop-the-world collector.
    • Consider a backup query function: Depending on the application case, it can be beneficial to offer an privileged query function to extract the critical canister state in several chunks. The runtime system maintains an extra memory reserve for query functions. Of course, such a function has to be implemented with a check that restricts it to authorized callers only. It is also important to test this function well.
    • Last resort if memory would be full: Assuming the memory is full with objects that have shortly become garbage before the memory space has been exhausted, the canister owner or controllers can call the system-level function __motoko_gc_trigger() multiple times to run extra GC increments and complete a GC run, for collecting the latest garbage in a full heap. Up to 100 calls of this function may be needed to complete a GC run in a 4GB memory space. The GC keeps an specific memory reserve to be able to perform its work even if the application has exhausted the memory. Usually, this functionality is not needed in practice but is only useful in such exceptional cases.

  • Allow type annotations on free-standing object/module/actor blocks, in order to perform a conformity check with an interface type (#4324).

0.10.3 (2023-12-20)

• motoko (moc)

  • Include doc comments to Candid interfaces generated via the --idl flag (#4334).

  • bugfix: fix broken implementations of Region.loadNat32, Region.storeNat32, Region.loadInt32, Region.storeInt32 (#4335). Values previously stored with the broken 32-bit operations must be loaded with care. If bit 0 is clear, the original value can be obtained by an arithmetic shift right by 1 bit. If bit 0 is set, the value cannot be trusted and should be ignored (it encodes some transient address of a boxed value).

• motoko-base

  • Added ExperimentalInternetComputer.performanceCounter function to get the raw performance counters (dfinity/motoko-base⁠#600).

  • Added Array.take function to get some prefix of an array (dfinity/motoko-base⁠#587).

  • Deprecated TrieSet.mem in favor of TrieSet.has (dfinity/motoko-base⁠#576).

  • bugfix: Array.chain(as, f) was incorrectly trapping when f(a) was an empty array (dfinity/motoko-base⁠#599).

0.10.2 (2023-11-12)

• motoko (moc)

  • bugfix: separate tag from underscore in coverage warnings (#4274).

  • Code compiled for targets WASI (-wasi-system-api) and pure Wasm (-no-system-api) can now use up to 4GB of (efficiently emulated) stable memory, enabling more offline testing of, for example, stable data structures built using libraries Regions.mo and ExperimentalStableMemory.mo. Note that any Wasm engine (such as wasmtime), used to execute such binaries, must support and enable Wasm features multi-memory and bulk-memory (as well as the standard NaN canonicalization) (#4256).

  • bugfix: fully implement Region.loadXXX/storeXXX for Int8, Int16 and Float (#4270).

  • BREAKING CHANGE (Minor): values of type Principal are now constrained to contain at most 29 bytes, matching the IC's notion of principal (#4268).

    In particular:

    • An actor import will be statically rejected if the binary representation of the (aliased) textually encoded principal contains strictly more than 29 bytes.

    • Principal.fromBlob(b) will trap if b contains strictly more than 29 bytes.

    • The actor literal, actor <exp>, will trap if the binary representation of of the textually encoded principal <exp> contains strictly more than 29 bytes.

• motoko-base

  • bugfix: fix Array.tabulateVar to avoid repeated side-effects (dfinity/motoko-base⁠#596)

0.10.1 (2023-10-16)

• motoko (moc)

  • bugfix: fix assertion failure renaming or-patterns (#4236, #4224).

  • bugfix: unsuccessful Candid decoding of an optional array now defaults to null instead of crashing (#4240).

  • bugfix: Candid decoding of an optional, unknown variant with a payload now succeeds instead of crashing (#4238).

  • Implement Prim.textLowercase and Prim.textUppercase (via Rust) (#4216).

  • perf: inline sharable low-level functions in generated coded, trading code size for reduced cycle count (#4212). Controlled by flags:

    • -fno-shared-code (default)
    • -fshared-code (legacy) (Helps mitigate the effect of the IC's new cost model, that increases the cost of function calls).

• motoko-base

  • Added Principal.toLedgerAccount (dfinity/motoko-base⁠#582).

  • Added Text.toLowercase and Text.toUppercase (dfinity/motoko-base⁠#590).

0.10.0 (2023-09-11)

• motoko (moc)

  • Added a new stable Region type of dynamically allocated, independently growable and isolated regions of IC stable memory (#3768). See documentation. BREAKING CHANGE: stable memory changes may occur that can prevent returning to previous moc versions.

  • Added doc comments in generated Candid files (#4178).

• motoko-base

  • Exposed conversions between adjacent fixed-width types (dfinity/motoko-base⁠#585).

  • Added library Region.mo offering isolated regions of IC stable memory (dfinity/motoko-base⁠#580).

0.9.8 (2023-08-11)

• motoko (moc)

  • Added numerical type conversions between adjacent fixed-width types (#4139).

  • Administrative: legacy-named release artefacts are no longer created (#4111).

0.9.7 (2023-07-18)

• motoko (moc)

  • Performance improvement: lower the default allocation for bignums (#4102).

  • Performance improvement: generate better code for pattern matches on some small variants (#4093).

  • bugfix: don't crash on import of Candid composite queries (#4128).

0.9.6 (2023-07-07)

• motoko (moc)

  • Allow canister controllers to call the __motoko_stable_var_info query endpoint (#4103). (Previously only self-queries were permitted.)

  • Performance improvement: reduced cycle consumption for allocating objects (#4095).

  • bugfix: reduced memory consumption in the Motoko Playground (#4106).

0.9.5 (2023-07-05)

• motoko (moc)

  • Allow identifiers in or-patterns (#3807). Bindings in alternatives must mention the same identifiers and have compatible types:

    let verbose = switch result {
      case (#ok) "All is good!";
      case (#warning why or #error why) "There is some problem: " # why;
    }

  • Performance improvement: improved cycle consumption allocating fixed-size objects (#4064). Benchmarks indicate up to 10% less cycles burned for allocation-heavy code, and 2.5% savings in realistic applications.

  • Administrative: binary build artefacts are now available according to standard naming conventions (thanks to EnzoPlayer0ne) (#3997). Please consider transitioning to downloading binaries following the new scheme, as legacy naming will be discontinued at some point in the future.

0.9.4 (2023-07-01)

• motoko (moc)

  • Allow multiline text literals (#3995). For example,

    "A horse walks into a bar.
    The barman says: `Why the long face?`"
    

    parses as:

    "A horse walks into a bar.\nThe barman says: `Why the long face?`"
    

  • Added pipe operator <exp1> |> <exp2> and placeholder expression _ (#3987). For example:

    Iter.range(0, 10) |>
      Iter.toList _ |>
        List.filter<Nat>(_, func n { n % 3 == 0 }) |>
          { multiples = _ };

    may, according to taste, be a more readable rendition of:

    { multiples =
       List.filter<Nat>(
         Iter.toList(Iter.range(0, 10)),
           func n { n % 3 == 0 }) };

    However, beware the change of evaluation order for code with side-effects.

  • BREAKING CHANGE (Minor):

    New keyword composite allows one to declare Internet Computer composite queries (#4003).

    For example,

    public shared composite query func sum(counters : [Counter]) : async Nat {
      var sum = 0;
      for (counter in counters.vals())  {
        sum += await counter.peek();
      };
      sum
    }

    has type:

    shared composite query [Counter] -> async Nat

    and can call both query and other composite query functions.

    See the documentation for full details.

  • Allow canister imports of Candid service constructors, ignoring the service arguments to import the instantiated service instead (with a warning) (#4041).

  • Allow optional terminal semicolons in Candid imports (#4042).

  • bugfix: allow signed float literals as static expressions in modules (#4063).

  • bugfix: improved reporting of patterns with record types in error messages (#4002).

• motoko-base

  • Added more Array (and Text) utility functions (thanks to roman-kashitsyn) (dfinity/motoko-base⁠#564).

0.9.3 (2023-06-19)

• motoko (moc)

  • Added fields sender_canister_version for actor class version tracking (#4036).

0.9.2 (2023-06-10)

• motoko (moc)

  • BREAKING CHANGE (Minor):

    or-patterns in function definitions cannot be inferred any more. The new error message suggests to add a type annotation instead. This became necessary in order to avoid potentially unsound types (#4012).

  • Added implementation for ic0.canister_version as a primitive (#4027).

  • Added a more efficient Prim.blobCompare (thanks to nomeata) (#4009).

  • bugfix: minor error in grammar for async* expressions (#4005).

• motoko-base

  • Add Principal.isController function (dfinity/motoko-base#558).

0.9.1 (2023-05-15)

• motoko (moc)

  • Added implementation for ic0.is_controller as a primitive (#3935).

  • Added ability to enable the new incremental GC in the Motoko Playground (#3976).

0.9.0 (2023-05-12)

• motoko (moc)

  • For beta testing: Add a new incremental GC, enabled with new moc flag --incremental-gc (#3837). The incremental garbage collector is designed to scale for large program heap sizes.

    The GC distributes its workload across multiple steps, called increments, that each pause the mutator (user's program) for only a limited amount of time. As a result, the GC work can fit within the instruction-limited IC messages, regardless of the heap size and the object structures.

    According to GC benchmark measurements, the incremental GC is more efficient than the existing copying, compacting, and generational GC in the following regards:

    • Scalability: Able to use the full heap space, 3x more object allocations on average.
    • Shorter interruptions: The GC pause has a maximum limit that is up to 10x shorter.
    • Lower runtimes: The number of executed instructions is reduced by 10% on average (compared to the copying GC).
    • Less GC overhead: The amount of GC work in proportion to the user's program work drops by 10-16%.

    The GC incurs a moderate memory overhead: The allocated WASM memory has been measured to be 9% higher on average compared to the copying GC, which is the current default GC.

    To activate the incremental GC under dfx, the following command-line argument needs to be specified in dfx.json:

    ...
      "type" : "motoko"
      ...
      "args" : "--incremental-gc"
    ...
    

  • bugfix: array.vals() now returns a working iterator for mutable arrays (#3497, #3967).

0.8.8 (2023-05-02)

• motoko (moc)

  • Performance improvement: optimised code generation for pattern matching that cannot fail (#3957).

0.8.7 (2023-04-06)

• motoko (moc)

  • Added ability to mo-doc for rendering documentation of nested modules (#3918).

  • bugfix: when re-adding recurrent timers, skip over past expirations (#3871).

  • bugfix: eliminated crash compiling local async functions that pattern match on arguments (#3910, #3916).

0.8.6 (2023-04-01)

• motoko (moc)

  • bugfix: avoid compiler crash (regression) when let-matching on constant variants (#3901, #3903).

  • Performance improvement: improved cycle usage when receiving messages (#3893).

0.8.5 (2023-03-20)

• motoko (moc)

  • Performance improvement: Values of variant type that are compile-time known are relegated to the static heap now and don't get allocated each time (#3878).

  • bugfix: the global timer expiration callback was called unnecessarily in the default mechanism (#3883).

0.8.4 (2023-03-11)

• motoko (moc)

  • Performance improvement: UTF-8 coding and validation is now properly tail recursive (#3842).

  • Performance improvement: eliminated bounds checking for certain array accesses (thanks to nomeata) (#3853).

  • Performance improvement: optimized {array, blob, text}.size() operations (thanks to nomeata) (#3863).

  • Performance improvement: efficient tuple results in switch statements (thanks to nomeata) (#3865).

  • Performance improvement: more efficient untagging operation (#3873).

  • bugfix: restored a grammar regression caused by let-else (#3869).

• motoko-base

  • Add Array.subArray function (dfinity/motoko-base#445).

  • BREAKING CHANGE (Minor)

    Optimized AssocList.{replace, find} to avoid unnecessary allocation (dfinity/motoko-base#535, dfinity/motoko-base#539). Note: this subtly changes the order in which the key-value pairs occur after replacement. May affect other containers that use AssocList.

  • Performance improvement: Optimized deletion for Trie/TrieMap (dfinity/motoko-base#525).

0.8.3 (2023-02-24)

• motoko (moc)

  • new 'let-else' construct for handling pattern-match failure (#3836). This is a frequently asked-for feature that allows to change the control-flow of programs when pattern-match failure occurs, thus providing a means against the famous "pyramid of doom" issue. A common example is look-ups:

    shared func getUser(user : Text) : async Id {
      let ?id = Map.get(users, user) else { throw Error.reject("no such user") };
      id
    }

    Similarly, an expression like

    (label v : Bool { let <pat> = <exp> else break v false; true })

    evaluates to a Bool, signifying whether <pat> matches <exp>.

  • Improve recursive deserialization capacity to match recursive serialization capacity by reducing Wasm stack consumption (#3809). Because of the bounds on recursion depth imposed by fixed-size stack, the advice remains the same: avoid deeply nested recursive data structures. Think "shallow trees good, very long lists bad".

  • bugfix: stack overflow in UTF-8 encode/decode for moc.js (#3825).

• motoko-base

  • add missing unshare : Tree<K, V> -> () method to class RBTree<K, V> to restore objects from saved state (dfinity/motoko-base#532).

0.8.2 (2023-02-17)

• motoko (moc)

  • Add compiler flag --rts-stack-pages <n> to override default number of pages dedicated to fixed runtime system stack. Now defaults to 32 pages (2MiB) (up from previous 2 pages/128KiB) (#3782). In emergencies, increasing this setting may improve your ability to deserialize deeply nested Candid or stable variable data.

  • Add stack overflow detection utilising reserved page (#3793).

  • Performance improvement: heap allocator speedup (#3090, #3790).

  • bugfix: avoid more heap-out-bounds errors during deserialization of stable variables by increasing default runtime system stack from 128KiB to 2MiB (#3782). Note: this is a partial fix, as issues with stack growth remain.

• motoko-base

  • bugfix: non-leaky deletion for RBTree (dfinity/motoko-base#524).

0.8.1 (2023-02-03)

• motoko (moc)

  • Performance improvement: faster heap allocation (#3765).

  • bugfix: async returns involving abbreviated tuple types no longer crash the compiler (#3740, #3741).

  • bugfix: avoid quadratic code expansion due to imported, but unused, actor classes (#3758).

0.8.0 (2023-01-27)

• motoko (moc)

  • BREAKING CHANGE

    Motoko now implements Candid 1.4 (dfinity/candid#311).

    In particular, when deserializing an actor or function reference, Motoko will now first check that the type of the deserialized reference is a subtype of the expected type and act accordingly.

    Very few users should be affected by this change in behaviour.

  • BREAKING CHANGE

    Failure to send a message no longer traps but, instead, throws a catchable Error with new error code #call_error (#3630).

    On the IC, the act of making a call to a canister function can fail, so that the call cannot (and will not be) performed. This can happen due to a lack of canister resources, typically because the local message queue for the destination canister is full, or because performing the call would reduce the current cycle balance of the calling canister to a level below its freezing threshold. Such call failures are now reported by throwing an Error with new ErrorCode #call_error { err_code = n }, where n is the non-zero err_code value returned by the IC. Like other errors, call errors can be caught and handled using try ... catch ... expressions, if desired.

    The constructs that now throw call errors, instead of trapping as with previous version of Motoko are:

    • calls to shared functions (including oneway functions that return ()). These involve sending a message to another canister, and can fail when the queue for the destination canister is full.
    • calls to local functions with return type async. These involve sending a message to self, and can fail when the local queue for sends to self is full.
    • async expressions. These involve sending a message to self, and can fail when the local queue for sends to self is full.
    • await expressions. These can fail on awaiting an already completed future, which requires sending a message to self to suspend and commit state.

    (On the other hand, async* (being delayed) cannot throw, and evaluating await* will at most propagate an error from its argument but not, in itself, throw.)

    Note that exiting a function call via an uncaught throw, rather than a trap, will commit any state changes and currently queued messages. The previous behaviour of trapping would, instead, discard, such changes.

    To appreciate the change in semantics, consider the following example:

    actor {
      var count = 0;
      public func inc() : async () {
        count += 1;
      };
      public func repeat() : async () {
        loop {
          ignore inc();
        }
      };
      public func repeatUntil() : async () {
        try {
          loop {
           ignore inc();
          }
        } catch (e) {
        }
      };
    }

    In previous releases of Motoko, calling repeat() and repeatUntil() would trap, leaving count at 0, because each infinite loop would eventually exhaust the message queue and issue a trap, rolling back the effects of each call. With this release of Motoko, calling repeat() will enqueue several inc() messages (around 500), then throw an Error and exit with the error result, incrementing the count several times (asynchronously). Calling repeatUntil() will also enqueue several inc() messages (around 500) but the error is caught so the call returns, still incrementing count several times (asynchronously).

    The previous semantics of trapping on call errors can be enabled with compiler option --trap-on-call-error, if desired, or selectively emulated by forcing a trap (e.g. assert false) when an error is caught.

    For example,

      public func allOrNothing() : async () {
        try {
          loop {
           ignore inc();
          }
        } catch (e) {
          assert false; // trap!
        }
      };

    Calling allOrNothing() will not send any messages: the loop exits with an error on queue full, the error is caught, but assert false traps so all queued inc() messages are aborted.

  • bugfix: system method inspect involving message with single tuple argument no longer crashes the compiler (#3732, #3733).

0.7.6 (2023-01-20)

• motoko (moc)

  • Added support for ManagementCanister.raw_rand in interpreters (#3693).

  • Added preliminary Viper support for old expressions in specifications and calls to private methods (#3675).

  • bugfix: in the default timer mechanism cancelTimer sometimes wouldn't actually stop a recurring timer (#3695).

  • bugfix: zero negation for floating point numbers in compiled code (#3676).

• motoko-base

  • Add user-facing timer functionality (dfinity/motoko-base#474).

  • Add Array.size (dfinity/motoko-base#486, dfinity/motoko-base#494).

  • Add TrieSet methods isEmpty, isSubset (dfinity/motoko-base#503).

  • BREAKING CHANGES (Minor):

    • renamed Float.neq to Float.neg (this was a misspelling)
    • renamed Nat.neq to Nat.neg (this was a misspelling)
    • removed second argument from bitnot (this was an oversight)

  • bugfix: Random.Finite.coin didn't use entropy correctly (dfinity/motoko-base#500).

  • bugfix: Trie.mergeDisjoint (dfinity/motoko-base#505).

  • bugfix: TrieSet.equals (dfinity/motoko-base#503).

  • Various documentation fixes and API usage examples.

0.7.5 (2022-12-23)

• motoko (moc)

  • Add new primitives for a default timer mechanism (#3542). These are

    setTimer : (delayNanos : Nat64, recurring : Bool, job : () -> async ()) -> (id : Nat)
    cancelTimer : (id : Nat) -> ()

    By defining a system func timer the default mechanism can now be overridden by a custom implementation. Additionally by supplying the command-line flag -no-timer all aspects of timers can be suppressed, e.g. for space- or security-sensitive purposes, thus effectively reverting canisters to the pre-timers era.

  • bugfix: silence bogus cascading errors in stable compatibility check (#3645).

0.7.4 (2022-12-07)

• motoko (moc)

  • Add new keywords async* and await* (note the *) for efficient abstraction of asynchronous code (#3609).

      <typ> ::= ...
        async* <typ>             delayed, asynchronous computation
      <exp> ::= ...
        async* <block-or-exp>    delay an asynchronous computation
        await* <block-or-exp>    execute a delayed computation (only in async, async*)
    

    This avoids the resource consumption and latency of async/await by only committing state and suspending execution when necessary in the await*-ed computation, not necessarily at the await* itself.

    WARNING: Unlike async/await:

    • an async* value has no effect unless await*-ed;
    • each await* of the same async* value repeats its effects.

    This feature is experimental and may evolve in future. Use with discretion. See the manual for details.

  • Suppress GC during IC canister_heartbeat, deferring any GC to the scheduled Motoko heartbeat system method (#3623). This is a temporary workaround, to be removed once DTS is supported for canister_heartbeat itself (#3622).

  • Add a new generational GC, enabled with new moc flag --generational-gc (#3495). The generational garbage collector optimizes for fast reclamation of short-lived objects. New objects are allocated in a young generation that is more frequently collected than the older objects that have already survived a GC run.

    For many cases, the generational GC is more efficient than the existing compacting GC and copying GCs:

    • Lower runtimes: Less number of executed instructions on average.
    • Shorter interruptions: Young generation collection entails shorter program interruptions.

    To activate the generational GC under dfx, the following command-line argument needs to be specified in dfx.json:

    ...
      "type" : "motoko"
      ...
      "args" : "--generational-gc"
    ...
    

  • moc.js : add trampoline and step limiter to interpreter, avoiding (some) stackoverflows and hangs (#3618, #3541). Enables execution of larger examples on web pages.

  • BREAKING CHANGE (Minor):

    Consider records with mutable fields as non-static (#3586). Consequently, an imported library declaring a mutable record is now rejected, not accepted, to be consistent with the declarations of mutable fields and mutable objects.

  • Experimental Viper integration by compiling a very narrow subset of Motoko to the verification intermediate language. See src/viper/README.md and the PR for details. (#3477).

• motoko-base

  • Unit tests for Trie and fix for disj (dfinity/motoko-base#438).

  • Respect Trie structure in filter (dfinity/motoko-base#431, dfinity/motoko-base#438).

  • Array module reimplementation, tests and documentation (dfinity/motoko-base#425,dfinity/motoko-base#432).

0.7.3 (2022-11-01)

• motoko (moc)

  • Statically reject shared functions and function types with type parameters (#3519, #3522).

  • Performance improvement: Array.init and Array.tabulate (#3526).

• motoko-base

  • Add some examples to Buffer library documentation (dfinity/motoko-base#420).

  • Fix another bug in Buffer library affecting filterEntries (dfinity/motoko-base#422).

0.7.2 (2022-10-25)

• motoko-base

  • Fix bugs in Buffer library affecting remove and filterEntries (dfinity/motoko-base#419).

0.7.1 (2022-10-24)

• motoko (moc)

  • Halve (default ir-checking) compilation times by optimizing type comparison and hashing (#3463)

  • Add support for type components in object type syntax (#3457, also fixes #3449)

    type Record = { type T = Nat; x : Nat};

  is now legal. Note the definition of T is neither recursive, nor bound in x : Nat, but can refer to an existing recursive type declared in an outer scope.

• motoko-base

  • Optimized and extended Buffer library (dfinity/motoko-base#417).

0.7.0 (2022-08-25)

• motoko (moc)

  • BREAKING CHANGE (Minor): Adds new syntax for merging records (objects) and adding/overwriting fields. The expression

    { baseA and baseB with field1 = val1; field2 = val2 }

    creates a new record by joining all (statically known) fields from baseA/B and the explicitly specified field1/2. This is a breaking change, as a new keyword with has been added. Restrictions for ambiguous and var fields from bases apply. (#3084)

  • Add new support for installing actor class instances on the IC, enabling specification of canister settings, install, upgrade and reinstall. (#3386)

    A new expression

      (system <exp> . <id>)
    

    where <exp> is an imported library and <id> is the name of an actor class, accesses a secondary constructor of the class that takes an additional argument controlling the installation.

    For example,

      await (system Lib.Node)(#upgrade a)(i);

    upgrades actor a with the code for a new instance of class Lib.Node, passing constructor argument (i).

  • Performance improvements for assigment-heavy code (thanks to nomeata) (#3406)

0.6.30 (2022-08-11)

• motoko (moc)

  • add primitives

    shiftLeft : (Nat, Nat32) -> Nat
    shiftRight : (Nat, Nat32) -> Nat

    for efficiently multiplying/dividing a Nat by a power of 2 (#3112)

  • add primitives

    rts_mutator_instructions : () -> Nat
    rts_collector_instructions : () -> Nat

    to report approximate IC instruction costs of the last message due to mutation (computation) and collection (GC), respectively (#3381)

• motoko-base

  • Add

    Buffer.fromArray
    Buffer.fromVarArray

    for efficiently adding an array to a Buffer (dfinity/motoko-base#389)

  • Add

    Iter.sort : (xs : Iter<A>, compare : (A, A) -> Order) : Iter<A>

    for sorting an Iter given a comparison function (dfinity/motoko-base#406)

  • Performance: HashMap now avoids re-computing hashes on resize (dfinity/motoko-base#394)

0.6.29 (2022-06-10)

• motoko (moc)

  • The language server now supports explicit symbol imports (thanks to rvanasa) (#3282)
  • The language server now has improved support for navigating to definitions in external modules (thanks to rvanasa) (#3263)
  • Added a primitive textCompare allowing more efficient three-way Text comparisons (#3298)
  • Fixed a typing bug with annotated, recursive records (#3268)

• motoko-base

  • Add

    ExperimentalInternetComputer.countInstruction : (comp : () -> ()) -> Nat64

    to count the Wasm instructions performed during execution of comp() (dfinity/motoko-base#381)

  • Add

    ExperimentalStableMemory.stableVarQuery : () -> (shared query () -> async {size : Nat64})

    for estimating stable variable storage requirements during upgrade (dfinity/motoko-base#365)

  • Performance improvement to Text.compare (dfinity/motoko-base#382)

0.6.28 (2022-05-19)

• motoko (moc)

  • Add to_candid, from_candid language constructs for Candid serialization to/from Blobs (#3155)
  • New system field 'inspect' for accepting/declining canister ingress messages (see doc) (#3210)

0.6.27 (2022-05-04)

• motoko (moc)

  • Importing modules by relative path is now more robust (#3215).
  • Performance: persisting stable variables to stable memory is now performed in streaming fashion, reducing heap consumption and copying during an upgrade (#3149).
  • Performance: local 32- and 64-bit numeric values are now stored in using unboxed form when possible (thanks to nomeata) (#3207).

• motoko-base

  • Fixed a bug in Trie.filter (and Trie.mapFilter) which could lead to missing matches in some cases (dfinity/motoko-base#371).

0.6.26 (2022-04-20)

• motoko (moc)

  • Performance: inline prim-wrapping functions (thanks to nomeata) (#3159)
  • Improve type pretty printer to mirror type parser (avoids producing unparseable stable variable signatures) (#3190)
  • Adds new flag --omit-metadata to omit certain metadata sections from actor (and actor class) Wasm (#3164)
  • Performance: avoid redundant heap allocation when deserializing compact Candid int and nat values (#3173)
  • Added a primitive to obtain stable variable memory footprint (#3049)

• motoko-base

  • Fixed the 32-bit range limitation of Hash.hash: Nat -> Nat32 and deprecate most functions in Hash (dfinity/motoko-base#366).
  • Add List.toIter (thanks to hoosan) (dfinity/motoko-base#336).

0.6.25 (2022-03-07)

• motoko (moc)

  • bugfix: fix bogus elision of type constructors sharing names with primitive types in --stable-types section and .most file (#3140)

0.6.24 (2022-03-06)

• motoko (moc)

  • bugfix: fix bogus identification of distinct type constructors in --stable-types section and .most file (#3140)

0.6.23 (2022-03-05)

• motoko (moc)

  • bugfix: fix pretty printing of (stable) types and #3128 (#3130)

    • Collect constructors transitively before emitting a .most file.
    • Modifies type pretty printer to produce well-formed types and stable type signatures.

0.6.22 (2022-02-24)

• motoko (moc)

  • Fix: remove bogus error when transitively importing module with selective field imports (#3121)
  • Fix: Treating eponymous types from separate candid files (#3103)

• Various reports from CI are now pushed to https://dfinity.github.io/motoko (#3113)

0.6.21 (2022-01-31)

• 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).

0.6.20 (2022-01-11)

• 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).

0.6.19 (2022-01-05)

• motoko-base

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

0.6.18 (2021-12-20)

• 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.

0.6.17 (2021-12-10)

• Improved handling of one-shot messages facilitating zero-downtime upgrades (#2938).
• Further performance improvements to the mark-compact garbage collector (#2952, #2973).
• Stable variable checking for moc.js (#2969).
• A bug was fixed in the scoping checker (#2977).

0.6.16 (2021-12-03)

• Minor performance improvement to the mark-compact garbage collector

0.6.15 (2021-11-26)

• Fixes crash when (ill-typed) switch expression on non-variant value has variant alternatives (#2934)

0.6.14 (2021-11-19)

• 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

0.6.13 (2021-11-19)

Pulled

0.6.12 (2021-10-22)

• 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};

0.6.11 (2021-10-08)

• Assertion error messages are now reproducible (#2821)

0.6.10 (2021-09-23)

• moc

  • documentation changes

• motoko-base

  • documentation changes

0.6.9 (2021-09-15)

• motoko-base

  • add Debug.trap : Text -> None (dfinity/motoko-base#288)

0.6.8 (2021-09-06)

• Introduce primitives for Int ⇔ Float conversions (#2733)
• Bump LLVM toolchain to version 12 (#2542)
• Support extended name linker sections (#2760)
• Fix crashing bug for formatting huge floats (#2737)

0.6.7 (2021-08-16)

• moc

  • Optimize field access by exploiting field ordering (#2708)
  • Fix handling of self references in mark-compact GC (#2721)
  • Restore CI reporting of perf-regressions (#2643)

• motoko-base:

  • Fix bug in AssocList.diff (dfinity/motoko-base#277)
  • Deprecate unsafe or redundant functions in library Option ( unwrap, assertSome, assertNull) (#275)

0.6.6 (2021-07-30)

• Vastly improved garbage collection scheduling: previously Motoko runtime would do GC after every update message. We now schedule a GC when

  1. Heap grows more than 50% and 10 MiB since the last GC, or
  2. Heap size is more than 3 GiB

  (1) is to make sure we don't do GC on tiny heaps or after only small amounts of allocation. (2) is to make sure that on large heaps we will have enough allocation space during the next message.

  This scheduling reduces cycles substantially, but may moderately increase memory usage.

  New flag --force-gc restores the old behavior.

• Fix bug in compacting gc causing unnecessary memory growth (#2673)

• Trap on attempt to upgrade when canister not stopped and there are outstanding callbacks. (This failure mode can be avoided by stopping the canister before upgrade.)

• Fix issue #2640 (leaked ClosureTable entry when awaiting futures fails).

0.6.5 (2021-07-08)

• Add alternative, compacting gc, enabled with new moc flag --compacting-gc. The compacting gc supports larger heap sizes than the default, 2-space copying collector.

  NOTE: Dfx 0.7.6 adds optional field "args" to dfx.json files, so Motoko canisters can specify moc command-line arguments. E.g.,

  ...
     "type" : "motoko"
     ...
     "args" : "--compacting-gc"
  ...

• Documentation fixes.

• Command line tools: --help option provides better documentation of command line options that have arguments.

• Fix issue #2319 (crash on import of Candid class).

0.6.4 (2021-06-12)

• For release builds, the banner (moc --version) now includes the release version.

• Fix MacOS release builds (the 0.6.3 tarball for MacOS contained the linux binaries)

0.6.3 (2021-06-10)

• Motoko is now open source!

• Better internal consistency checking of the intermediate representation

0.6.2 (2021-05-24)

• motoko-base:

  • reformat to style guidelines
  • add type bindings Nat.Nat, Nat8.Nat8 etc. to libraries for primitive types.

• Bugfix: generation of candid from Motoko:

  • no longer confused by distinct, but eponymous, type definitions (Bug: #2529);
  • numbers eponymous types and specializations from 1 (not 2);
  • avoids long chains of type equalities by normalizing before translation.

0.6.1 (2021-04-30)

• Internal: Update to IC interface spec 0.17 (adapt to breaking change to signature of create_canister)

0.6.0 (2021-04-16)

• BREAKING CHANGE: The old-style object and block syntax deprecated in 0.5.0 is finally removed.

• Record punning: As already supported in patterns, short object syntax in expressions now allows omitting the right-hand side if it is an identifier of the same name as the label. That is,

  {a; b = 1; var c}

  is short for

  {a = a; b = 1; var c = c}

  assuming respective variables are in scope.

• BREAKING CHANGE: The types Word8, Word16, Word32 and Word64 have been removed. This also removed the blob.bytes() iterator.

  Motoko base also dropped the Word8, Word16, Word32 and Word64 modules.

  This concludes the transition to the other fixed-width types that began with version 0.5.8

• BREAKING CHANGE (Minor): await on a completed future now also commits state and suspends computation, to ensure every await, regardless of its future's state, is a commit point for state changes and tentative message sends.

  (Previously, only awaits on pending futures would force a commit and suspend, while awaits on completed futures would continue execution without an incremental commit, trading safety for speed.)

• motoko-base: fixed bug in Text.compareWith.

0.5.15 (2021-04-13)

• Bugfix: Blob.toArray was broken.

0.5.14 (2021-04-09)

• BREAKING CHANGE (Minor): Type parameter inference will no longer default under-constrained type parameters that are invariant in the result, but require an explicit type argument. This is to avoid confusing the user by inferring non-principal types.

  For example, given (invariant) class Box<A>:

    class Box<A>(a : A) { public var value = a; };

  the code

    let box = Box(0); // rejected

  is rejected as ambiguous and requires an instantiation, type annotation or expected type. For example:

    let box1 = Box<Int>(0); // accepted
    let box2 : Box<Nat> = Box(0); // accepted

  Note that types Box<Int> and Box<Nat> are unrelated by subtyping, so neither is best (or principal) in the ambiguous, rejected case.

• Bugfix: Type components in objects/actors/modules correctly ignored when involved in serialization, equality and debug_show, preventing the compiler from crashing.

• motoko-base: The Text.hash function was changed to a better one. If you stored hashes as stable values (which you really shouldn't!) you must rehash after upgrading.

• motoko-base: Conversion functions between Blob and [Nat8] are provided.

• When the compiler itself crashes, it will now ask the user to report the backtrace at the DFINITY forum

0.5.13 (2021-03-25)

• The moc interpreter now pretty-prints values (as well as types) in the repl, producing more readable output for larger values.

• The family of Word types are deprecated, and mentioning them produces a warning. These type will be removed completely in a subsequent release. See the user’s guide, section “Word types”, for a migration guide.

• motoko base: because of this deprecation, the Char.from/toWord32() functions are removed. Migrate away from Word types, or use Word32.from/ToChar for now.

0.5.12 (2021-03-23)

• The moc compiler now pretty-prints types in error messages and the repl, producing more readable output for larger types.

• motoko base: fixed bug in Text.mo affecting partial matches in, for example, Text.replace (GH issue #234).

0.5.11 (2021-03-12)

• The moc compiler no longer rejects occurrences of private or local type definitions in public interfaces.

  For example,

  module {
    type List = ?(Nat, List); // private
    public func cons(n : Nat, l : List) : List { ?(n , l) };
  }

  is now accepted, despite List being private and appearing in the type of public member cons.

• Type propagation for binary operators has been improved. If the type of one of the operands can be determined locally, then the other operand is checked against that expected type. This should help avoiding tedious type annotations in many cases of literals, e.g., x == 0 or 2 * x, when x has a special type like Nat8.

• The moc compiler now rejects type definitions that are non-productive (to ensure termination).

  For example, problematic types such as:

  type C = C;
  type D<T, U> = D<U, T>;
  type E<T> = F<T>;
  type F<T> = E<T>;
  type G<T> = Fst<G<T>, Any>;

  are now rejected.

• motoko base: Text now contains decodeUtf8 and encodeUtf8.

0.5.10 (2021-03-02)

• User defined deprecations

  Declarations in modules can now be annotated with a deprecation comment, which make the compiler emit warnings on usage.

  This lets library authors warn about future breaking changes:

  As an example:

  module {
    /// @deprecated Use `bar` instead
    public func foo() {}
  
    public func bar() {}
  }

  will emit a warning whenever foo is used.

• The moc compiler now rejects type definitions that are expansive, to help ensure termination. For example, problematic types such as type Seq<T> = ?(T, Seq<[T]>) are rejected.

• motoko base: Time.Time is now public

0.5.9 (2021-02-19)

• The moc compiler now accepts the -Werror flag to turn warnings into errors.

• The language server now returns documentation comments alongside completions and hover notifications

0.5.8 (2021-02-12)

• Wrapping arithmetic and bit-wise operations on NatN and IntN

  The conventional arithmetic operators on NatN and IntN trap on overflow. If wrap-around semantics is desired, the operators +%, -%, *% and **% can be used. The corresponding assignment operators (+%= etc.) are also available.

  Likewise, the bit fiddling operators (&, |, ^, <<, >>, <<>, <>> etc.) are now also available on NatN and IntN. The right shift operator (>>) is an unsigned right shift on NatN and a signed right shift on IntN; the +>> operator is not available on these types.

  The motivation for this change is to eventually deprecate and remove the WordN types.

  Therefore, the wrapping arithmetic operations on WordN are deprecated and their use will print a warning. See the user’s guide, section “Word types”, for a migration guide.

• For values x of type Blob, an iterator over the elements of the blob x.vals() is introduced. It works like x.bytes(), but returns the elements as type Nat8.

• mo-doc now generates cross-references for types in signatures in both the Html as well as the Asciidoc output. So a signature like fromIter : I.Iter<Nat> -> List.List<Nat> will now let you click on I.Iter or List.List and take you to their definitions.

• Bugfix: Certain ill-typed object literals are now prevented by the type checker.

• Bugfix: Avoid compiler aborting when object literals have more fields than their type expects.

0.5.7 (2021-02-05)

• The type checker now exploits the expected type, if any, when typing object literal expressions. So { x = 0 } : { x : Nat8 } now works as expected instead of requiring an additional type annotation on 0.

0.5.6 (2021-01-22)

• The compiler now reports errors and warnings with an additional error code This code can be used to look up a more detailed description for a given error by passing the --explain flag with a code to the compiler. As of now this isn't going to work for most codes because the detailed descriptions still have to be written.
• Internal: The parts of the RTS that were written in C have been ported to Rust.

0.5.5 (2021-01-15)

• new moc command-line arguments --args <file> and --args0 <file> for reading newline/NUL terminated arguments from <file>.
• motoko base: documentation examples are executable in the browser

0.5.4 (2021-01-07)

• Option blocks do ? <block> and option checks <exp> !. Inside an option block, an option check validates that its operand expression is not null. If it is, the entire option block is aborted and evaluates to null. This simplifies consecutive null handling by avoiding verbose switch expressions.

  For example, the expression do? { f(x!, y!) + z!.a } evaluates to null if either x, y or z is null; otherwise, it takes the options' contents and ultimately returns ?r, where r is the result of the addition.

• BREAKING CHANGE (Minor): The light-weight do <exp> form of the recently added, more general do <block-or-exp> form, is no longer legal syntax. That is, the argument to a do or do ? expression must be a block { ... }, never a simple expression.

0.5.3 (2020-12-10)

• Nothing new, just release moc.js to CDN

0.5.2 (2020-12-04)

• Bugfix: gracefully handle importing ill-typed actor classes

0.5.1 (2020-11-27)

• BREAKING CHANGE: Simple object literals of the form {a = foo(); b = bar()} no longer bind the field names locally. This enables writing expressions like func foo(a : Nat) { return {x = x} }.

  However, this breaks expressions like {a = 1; b = a + 1}. Such object shorthands now have to be written differently, e.g., with an auxiliary declaration, as in let a = 1; {a = a; b = a + 1}, or by using the "long" object syntax object {public let a = 1; public let b = a + 1}.

0.5.0 (2020-11-27)

• BREAKING CHANGE: Free-standing blocks are disallowed

  Blocks are only allowed as sub-expressions of control flow expressions like if, loop, case, etc. In all other places, braces are always considered to start an object literal.

  To use blocks in other positions, the new do <block> expression can be used.

  The more liberal syntax is still allowed for now but deprecated, i.e., produces a warning.

• BREAKING CHANGE: actor creation is regarded as asynchronous:

  • Actor declarations are asynchronous and can only be used in asynchronous contexts.
  • The return type of an actor class, if specified, must be an async actor type.
  • To support actor declaration, the top-level context of an interpreted program is an asynchronous context, allowing implicit and explicit await expressions.

  (Though breaking, this change mostly affects interpreted programs and compiled programs with explicate actor class return types)

• Candid support is updated to latest changes of the Candid spec, in particular the ability to extend function with optional parameters in a backward compatible way.

  Motoko passes the official Candid compliance test suite.

• RTS: Injecting a value into an option type (? <exp>) no longer requires heap allocation in most cases. This removes the memory-tax of using iterators.

• Bugfix: Passing cycles to the instantiation of an actor class works now.

• Various bug fixes and documentation improvements.

0.4.6 (2020-11-13)

• Significant documentation improvements
• Various bugfixes
• Improved error messages
• Initial DWARF support
• Candid compliance improvements:
  • Strict checking of utf8 strings
  • More liberal parsing of leb128-encoded numbers
• New motoko-base:
  • The Random library is added

0.4.5 (2020-10-06)

• BREAKING CHANGE: a library containing a single actor class is imported as a module, providing access to both the class type and class constructor function as module components. Restores the invariant that imported libraries are modules.
• Backend: Compile captured actor class parameters statically (#2022)
• flip the default for -g (#1546)
• Bug fix: reject array indexing as non-static (could trap) (#2011)
• Initialize tuple length fields (#1992)
• Warns for structural equality on abstract types (#1972)
• Funds Imperative API (#1922)
• Restrict subtyping (#1970)
• Continue labels always have unit codomain (#1975)
• Compile.ml: target and use new builder call pattern (#1974)
• fix scope var bugs (#1973)

0.4.4 (2020-09-21)

• Actor class export
• Accept unit installation args for actors
• Reject platform actor (class) programs with additional decs
• Handle IO exceptions at the top-level
• RTS: Remove duplicate array and blob allocation code
• RTS: Fix pointer arithmetic in BigInt collection function

0.4.3 (2020-09-14)

• Preliminary support for actor class import and dynamic canister installation. Surface syntax may change in future.
• BREAKING CHANGE: a compilation unit/file defining an actor or actor class may only have leading import declarations; other leading declarations (e.g. let or type) are no longer supported.
• Rust GC

0.4.2 (2020-08-18)

• Polymorphic equality. == and != now work on all shareable types.

0.4.1 (2020-08-13)

• Switching to bumping the third component of the version number
• Bugfix: clashing declarations via function and class caught (#1756)
• Bugfix: Candid bool decoding rejects invalid input (#1783)
• Canisters can take installation arguments (#1809) NB: Communicating the type of the canister installation methods is still missing.
• Optimization: Handling of Bool in the backend.

0.4 (2020-08-03)

• Candid pretty printer to use shorthand when possible (#1774)
• fix candid import to use the new id format (#1787)

0.3 (2020-07-31)

• Fixes an issue with boolean encoding to Candid
• Converts the style guide to asciidocs

0.2 (2020-07-30)

• The Blob type round-trips through candid type export/import (#1744)
• Allow actor classes to know the caller of their constructor (#1737)
• Internals: Prim.time() provided (#1747)
• Performance: More dead code removal (#1752)
• Performance: More efficient arithmetic with unboxed values (#1693, #1757)
• Canister references are now parsed and printed according to the new base32-based textual format (#1732).
• The runtime is now embedded into moc and need not be distributed separately (#1772)

0.1 (2020-07-20)

• Beginning of the changelog. Released with dfx-0.6.0.