Language reference

Use this reference when you know what you want to write and need its syntax or behavior. For a guided introduction, start with the tutorial. The function library has a separate alphabetical index.

• Tutorial
• Built-in functions

Values and types

Numeric types are int8, int16, int32, int64, uint8, uint16, uint32, uint64, float32 and float64. The aliases int, uint and float mean their 64-bit counterparts on every target. Bool has the values true and false; String holds UTF-8 text. Arrays use [T]; numerical tensors use Tensor[T, dimensions]. A scalar and a rank-zero tensor are different types. Define domain-specific values with records and enums.

• Lexical structure, bindings and expressions
• Numeric types and arithmetic
• String literals and Unicode indexing
• Array values
• Tensor types, shapes and indexing
• Record and enum declarations

Mutation at a glance

Reassignment changes a local binding; an element write changes array storage. These are different operations.

Operation	Rule
Reassign a numeric or Bool scalar	Allowed locally; the type stays fixed
Replace a numeric or Bool CPU array binding	Allowed; existing aliases retain the previous array
Write a numeric or Bool array element	Requires writable storage and no unfinished task readers
Write through an array parameter	The parameter must declare mut
Edit a String or tensor in place	Not supported; construct a new value
Update a record	Use with to construct a new record

• Array access, copying, sorting and shared readers
• Function parameter access contracts

Functions and control flow

Functions return their final expression. A function value can be passed to another function or retain values from its defining scope as a closure. if chooses a branch, while repeats a body, for visits array elements or integer ranges, and match selects a declared enum or error alternative. Conditions and loops support both statement and expression forms; break and continue control the nearest loop. Function signatures record parameter access and any expected-error channel.

• Definitions, function values, closures and recursion
• Conditions, loops, exits and pattern matching
• Error declarations, try, fail and catch
• Imports, exports and re-exports

Tasks and placement

spawn, await, parallel, try and on are language constructs, not ordinary functions. A parallel scope owns its children and settles them before leaving. Device selectors and transfer are documented separately as callable built-ins. A tensor result awaited from a GPU task remains resident until an explicit transfer changes its placement.

• Structured CPU tasks
• GPU placement
• Task and device built-ins

Operators and evaluation

Numeric expressions use +, -, *, / and integer remainder %. String concatenation uses +. Comparison operators are ==, !=, <, <=, > and >=; their accepted operands must have compatible types. Bool expressions use not, and and or. Conditions and Boolean and/or use lazy selection, so an unselected expression does not run. Comparison chaining requires explicit grouping rather than Python-style chained comparisons.

Multiplication, division and remainder bind more tightly than addition and subtraction. The -> pipeline passes its left expression as the first argument of the call on its right. Use parentheses to make the intended grouping explicit, especially when combining a pipeline with arithmetic or comparisons.

Indexes are zero-based. Array and String indexing uses one index; tensor indexing uses one per dimension. Bounds are checked. An indexed expression reads a value. Numeric and Bool CPU arrays also permit checked element assignment when the caller has write access and no unfinished task readers share that storage. Strings and tensors do not support in-place edits.