Future.Prelude

The prelude module holds proposal-driven extensions to the prelude, including
iterable helpers, option/result types, and attribute binding.

Values

const ZE_007

const ZE_007 = "https://zirric.knabel.dev/proposals/ZE-007-attribute-binding"

ZE-007: Attribute Binding.

const ZE_008

const ZE_008 = "https://zirric.knabel.dev/proposals/ZE-008-error-handling"

ZE-008: Error Handling.

const ZE_009

const ZE_009 = "https://zirric.knabel.dev/proposals/ZE-009-option-values"

ZE-009: Option Values.

const ZE_010

const ZE_010 = "https://zirric.knabel.dev/proposals/ZE-010-iterable"

ZE-010: Iterable.

Attributes

attr Bound

@Proposal(ZE_007)
attr Bound {}

A bound function of an attribute receives the targeted value as first argument.

Example:

attr Error {
  @Bound()
  debug(err) -> String
}

@Error(fn(err) { return err.message })
data MessageError {
  message: String
}

MessageError("msg")[@Error].debug()

attr Countable

@Proposal(ZE_010)
attr Countable {
  length(value: @Countable) -> Int
}

Denotes that a type is countable and has a length.

Members:

• length(value: @Countable) -> Int

attr Iterable

@Proposal(ZE_010)
attr Iterable {
  iterate(value: @Iterable, yield: Func)
}

Marks a type as iterable. This allows using for ... <- ... on the type.

Members:

• iterate(value: @Iterable, yield: Func)

attr Error

@Proposal(ZE_008)
attr Error {
  @Bound()
  debug(err) -> String
}

Marks a type as an error type.

Members:

• @Bound() debug(err) -> String — Returns a debug string representation
  of the error.

attr AnyResult

attr AnyResult {}

Marks a type as a result type. It is expected that types marked with
@AnyResult are unions. Marking a type with @AnyResult enables additional
syntactic sugar for working with result types:

• result!.value resolves to a Result with either Ok(value) or Err(error).
• result !! "default value" resolves to the value of Ok or the provided
  default value if Err.

attr AnyOption

attr AnyOption {}

Marks a type as an option type. It is expected that types marked with
@AnyOption are unions. Marking a type with @AnyOption enables additional
syntactic sugar for working with option types:

• option?.value resolves to an Option with either Some(value) or None.
• option ?? "default value" resolves to the value of Some or the provided
  default value if None.

Data

data Range

@Proposal(ZE_010)
@Countable(_rangeCount)
@Iterable(_rangeIterate)
data Range {
  start: Int
  end: Int
}

Represents an open range of integers from start (inclusive) to end (exclusive).
Can be created using the syntax start..<end.

Fields:

• start: Int
• end: Int

data ClosedRange

@Proposal(ZE_010)
@Countable(_rangeCount)
@Iterable(_rangeIterate)
data ClosedRange {
  start: Int
  end: Int
}

Represents a closed range of integers from start (inclusive) to end (inclusive).
Can be created using the syntax start...end.

Fields:

• start: Int
• end: Int

data Ok

@Proposal(ZE_008)
data Ok {
  value
}

The successful result.

Fields:

• value — The value of the successful result.

data Err

@Proposal(ZE_008)
@Error(fn(err) { return err.error.debug(err.error) })
data Err {
  error: @Error
}

The error result.

Fields:

• error: @Error — The error of the result. Must be a type marked with
  @Error.

data Some

@Proposal(ZE_009)
data Some {
  value
}

The present value.

Fields:

• value — The value that is present.

data None

@Proposal(ZE_009)
data None

The absent value.

Union

union Result

@Proposal(ZE_008)
@AnyResult()
union Result

A result type that can be either Ok or Err. Used for functions that can fail.
The following syntactic sugar exists for working with Result types:

• result!.value
• result !! "default value"
• @String! which is equivalent to @Type(Result) @OkType(String)

Members:

• Ok
• Err

union Option

@Proposal(ZE_009)
union Option

An option type that can be either Some or None. Used for values that may or may
not be present. The following syntactic sugar exists for working with Option
types:

• option?.value
• option ?? "default value"
• @String? which is equivalent to @Type(Option) @SomeType(String)

Members:

• Some
• None

Functions

fn _arrayIterate

fn _arrayIterate(v, yield)

No documentation.

fn _dictIterate

fn _dictIterate(v, yield)

No documentation.

fn _stringIterate

fn _stringIterate(v, yield)

No documentation.

fn _rangeCount

fn _rangeCount(v)

No documentation.

fn _rangeIterate

fn _rangeIterate(v, yield)

No documentation.

fn _closedRangeCount

fn _closedRangeCount(v)

No documentation.

fn _closedRangeIterate

fn _closedRangeIterate(v, yield)

No documentation.