Plain-language glossary#

Use this page when the guide uses an unfamiliar term. Follow a link for the exact rules and examples.

Term	Meaning in this guide
Binding	A name attached to a value. `let` prevents reassignment; `var` allows a replacement value.
Scope	The part of a program where a name is visible. Nested blocks create nested scopes.
Module	One `.ms` source file. It imports and exports individual declarations.
Record	A value with named fields, such as a customer with a name and email.
Nominal type	A type identified by its declaration. Two records with identical fields can still be different types.
Alternative	A type with a fixed set of cases. A value is one case at a time and may carry that case’s data.
Contract / interface	A declared set of operations an implementation must provide.
Generic parameter	A placeholder for a type, such as `T` in `List[T]`.
Bound	A requirement on a type parameter, such as supporting comparison or supplying a particular operation.
Equal	A standard interface for comparing values with `==`, `!=`, or `equals`. Built-in data compares by contents; explicit implementations can select domain identity.
Hashable	A standard interface for computing lookup hashes. Map keys and set elements must also implement Equal.
Intrinsic / prelude	Types and interfaces available without imports, including Optional, Result, Error, and the standard equality interfaces.
Result	Either a success value or an expected error value. Callers can handle or forward the error.
Optional	Either a present value or `none`. Absence does not carry an error explanation.
Fault	A programming failure, such as a violated invariant. It ends the current operation after cleanup.
Closure / capture	A function value that keeps the surrounding values it uses. Captured bindings are snapshots.
Alias	Another reference to the same object. Closing a resource affects every alias.
Resource lifetime	How long a file, connection, or other external resource remains open and usable.
Sharing	Values may be passed between operations. Local mutable queues need explicit synchronization; sharing does not keep resources open.
Capability / authority	A service object that permits external operations, obtained through a host accessor or passed to a helper.
Effect	External behavior reachable from an operation, such as reading, writing, or calling a service.
Operation / group	One invocation started by a concurrency API / the invocations started by one task group.
Join	Wait until every started operation has finished, including its cleanup.
Execution context	Runtime state carrying an operation’s cancellation signal and deadline. The runtime passes it internally.
Cancellation checkpoint	A point where work checks whether it should stop and unwind.
Unwind	Leave active scopes and run their registered cleanup.
Shielded cleanup	Cleanup that can run despite the cancellation or deadline that ended ordinary work.
Host	The runtime entry point that runs a CLI application or handles HTTP requests.
Typed IR	The compiler’s internal program representation after names and types have been checked.
Lowering	Translating checked Manuscript operations into generated Go while preserving their behavior.
Conformance	Tests and evidence that the implementation follows the language’s rules.
Normative	Defines a required rule. Other explanations and examples must agree with it.