Randomness

[Source]

Draw methods are non-partial. During replay, if the recorded choice sequence is exhausted or a type mismatch is detected, draw methods fall back to fresh generation and the runner detects it.

Integer methods generate values in the closed interval [min, max]. Floating-point methods scale onto [min, max]; min is always reachable, max is an approximate upper bound due to floating-point rounding.

class ref Randomness

Constructors

create

[Source]

new ref create(
  seed1: U64 val = 42,
  seed2: U64 val = 0)
: Randomness ref^

Parameters

• seed1: U64 val = 42
• seed2: U64 val = 0

Returns

• Randomness ref^

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Public Functions

u8

[Source]

Generate a U8 in closed interval [min, max].

fun ref u8(
  min: U8 val = U8.min_value(),
  max: U8 val = U8.max_value())
: U8 val

Parameters

• min: U8 val = U8.min_value()
• max: U8 val = U8.max_value()

Returns

• U8 val

---

u16

[Source]

Generate a U16 in closed interval [min, max].

fun ref u16(
  min: U16 val = U16.min_value(),
  max: U16 val = U16.max_value())
: U16 val

Parameters

• min: U16 val = U16.min_value()
• max: U16 val = U16.max_value()

Returns

• U16 val

---

u32

[Source]

Generate a U32 in closed interval [min, max].

fun ref u32(
  min: U32 val = U32.min_value(),
  max: U32 val = U32.max_value())
: U32 val

Parameters

• min: U32 val = U32.min_value()
• max: U32 val = U32.max_value()

Returns

• U32 val

---

u64

[Source]

Generate a U64 in closed interval [min, max].

fun ref u64(
  min: U64 val = U64.min_value(),
  max: U64 val = U64.max_value())
: U64 val

Parameters

• min: U64 val = U64.min_value()
• max: U64 val = U64.max_value()

Returns

• U64 val

---

u128

[Source]

Generate a U128 in closed interval [min, max].

fun ref u128(
  min: U128 val = U128.min_value(),
  max: U128 val = U128.max_value())
: U128 val

Parameters

• min: U128 val = U128.min_value()
• max: U128 val = U128.max_value()

Returns

• U128 val

---

ulong

[Source]

Generate a ULong in closed interval [min, max].

fun ref ulong(
  min: ULong val = ULong.min_value(),
  max: ULong val = ULong.max_value())
: ULong val

Parameters

• min: ULong val = ULong.min_value()
• max: ULong val = ULong.max_value()

Returns

• ULong val

---

usize

[Source]

Generate a USize in closed interval [min, max].

fun ref usize(
  min: USize val = USize.min_value(),
  max: USize val = USize.max_value())
: USize val

Parameters

• min: USize val = USize.min_value()
• max: USize val = USize.max_value()

Returns

• USize val

---

i8

[Source]

Generate an I8 in closed interval [min, max].

fun ref i8(
  min: I8 val = I8.min_value(),
  max: I8 val = I8.max_value())
: I8 val

Parameters

• min: I8 val = I8.min_value()
• max: I8 val = I8.max_value()

Returns

• I8 val

---

i16

[Source]

Generate an I16 in closed interval [min, max].

fun ref i16(
  min: I16 val = I16.min_value(),
  max: I16 val = I16.max_value())
: I16 val

Parameters

• min: I16 val = I16.min_value()
• max: I16 val = I16.max_value()

Returns

• I16 val

---

i32

[Source]

Generate an I32 in closed interval [min, max].

fun ref i32(
  min: I32 val = I32.min_value(),
  max: I32 val = I32.max_value())
: I32 val

Parameters

• min: I32 val = I32.min_value()
• max: I32 val = I32.max_value()

Returns

• I32 val

---

i64

[Source]

Generate an I64 in closed interval [min, max].

fun ref i64(
  min: I64 val = I64.min_value(),
  max: I64 val = I64.max_value())
: I64 val

Parameters

• min: I64 val = I64.min_value()
• max: I64 val = I64.max_value()

Returns

• I64 val

---

i128

[Source]

Generate an I128 in closed interval [min, max].

fun ref i128(
  min: I128 val = I128.min_value(),
  max: I128 val = I128.max_value())
: I128 val

Parameters

• min: I128 val = I128.min_value()
• max: I128 val = I128.max_value()

Returns

• I128 val

---

ilong

[Source]

Generate an ILong in closed interval [min, max].

fun ref ilong(
  min: ILong val = ILong.min_value(),
  max: ILong val = ILong.max_value())
: ILong val

Parameters

• min: ILong val = ILong.min_value()
• max: ILong val = ILong.max_value()

Returns

• ILong val

---

isize

[Source]

Generate an ISize in closed interval [min, max].

fun ref isize(
  min: ISize val = ISize.min_value(),
  max: ISize val = ISize.max_value())
: ISize val

Parameters

• min: ISize val = ISize.min_value()
• max: ISize val = ISize.max_value()

Returns

• ISize val

---

f32

[Source]

Generate an F32 in the range from min to max.

fun ref f32(
  min: F32 val = 0.0,
  max: F32 val = 1.0)
: F32 val

Parameters

• min: F32 val = 0.0
• max: F32 val = 1.0

Returns

• F32 val

---

f64

[Source]

Generate an F64 in the range from min to max.

fun ref f64(
  min: F64 val = 0.0,
  max: F64 val = 1.0)
: F64 val

Parameters

• min: F64 val = 0.0
• max: F64 val = 1.0

Returns

• F64 val

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bool

[Source]

Generate a random Bool value.

fun ref bool()
: Bool val

Returns

• Bool val

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forced_bool

[Source]

Record a predetermined Bool. This choice is excluded from shrinking. Use when the outcome is fixed by the generator's structure (e.g., elements below a collection minimum).

fun ref forced_bool(
  value: Bool val)
: Bool val

Parameters

• value: Bool val

Returns

• Bool val

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shuffle[T: T]

[Source]

Shuffle the array in place using Fisher-Yates, recording one integer choice per element as the swap index.

fun ref shuffle[T: T](
  array: Array[T] ref)
: None val ?

Parameters

• array: Array[T] ref

Returns

• None val ?

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start_span

[Source]

Mark the beginning of a structural span in the choice sequence. Spans let the shrinker understand generator structure — for example, which choices belong to a single collection element.

fun ref start_span(
  label: SpanLabel)
: None val

Parameters

• label: SpanLabel

Returns

• None val

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end_span

[Source]

Close the most recently opened span. If discard is true, the span is marked as discarded (e.g., a filter rejection).

Errors if no span is open (mismatched start_span/end_span calls).

fun ref end_span(
  discard: Bool val = false)
: None val ?

Parameters

• discard: Bool val = false

Returns

• None val ?

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