Documentation

System built-ins

Flux contains many preassigned values. These preassigned values are defined in the source files for the various built-in packages.

When a built-in value is not expressible in Flux, its value may be defined by the hosting environment. All such values must have a corresponding builtin statement to declare the existence and type of the built-in value.

BuiltinStatement = "builtin" identifier ":" TypeExpression .
TypeExpression   = MonoType ["where" Constraints] .

MonoType     = Tvar | BasicType | ArrayType | StreamType | VectorType | RecordType | FunctionType .
Tvar         = "A"  "Z" .
BasicType    = "int" | "uint" | "float" | "string" | "bool" | "time" | "duration" | "bytes" | "regexp" .
ArrayType    = "[" MonoType "]" .
StreamType   = "stream" "[" MonoType "]" .
VectorType   = "vector" "[" MonoType "]" .
RecordType   = ( "{" [RecordTypeProperties] "}" ) | ( "{" Tvar "with" RecordTypeProperties "}" ) .
FunctionType = "(" [FunctionTypeParameters] ")" "=>" MonoType .

RecordTypeProperties = RecordTypeProperty { "," RecordTypeProperty } .
RecordTypeProperty   = Label ":" MonoType .
Label = identifier | string_lit

FunctionTypeParameters = FunctionTypeParameter { "," FunctionTypeParameter } .
FunctionTypeParameter = [ "<-" | "?" ] identifier ":" MonoType .

Constraints = Constraint { "," Constraint } .
Constraint  = Tvar ":" Kinds .
Kinds       = identifier { "+" identifier } .
Example
builtin filter : (<-tables: stream[T], fn: (r: T) => bool) => stream[T]

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The future of Flux

Flux is going into maintenance mode. You can continue using it as you currently are without any changes to your code.

Flux is going into maintenance mode and will not be supported in InfluxDB 3.0. This was a decision based on the broad demand for SQL and the continued growth and adoption of InfluxQL. We are continuing to support Flux for users in 1.x and 2.x so you can continue using it with no changes to your code. If you are interested in transitioning to InfluxDB 3.0 and want to future-proof your code, we suggest using InfluxQL.

For information about the future of Flux, see the following: