Pick a constructor with a given distribution, and fill its fields with recursive calls to arbitrary.

Example

genericArbitrary (2 % 3 % 5 % ()) :: Gen a

Picks the first constructor with probability 2/10, the second with probability 3/10, the third with probability 5/10.

Pick every constructor with equal probability. Equivalent to genericArbitrary uniform.

genericArbitraryU :: Gen a

arbitrary for types with one constructor. Equivalent to genericArbitraryU, with a stricter type.

genericArbitrarySingle :: Gen a

Decrease size at every recursive call, but don't do anything different at size 0.

genericArbitraryRec (7 % 11 % 13 % ()) :: Gen a

N.B.: This replaces fields of type [t] with listOf' arbitrary.

Decrease size to ensure termination for recursive types, looking for base cases once the size reaches 0.

genericArbitrary' (17 % 19 % 23 % ()) :: Gen a

N.B.: This replaces fields of type [t] with listOf' arbitrary.

Equivalent to genericArbitrary' uniform.

genericArbitraryU :: Gen a

N.B.: This replaces fields of type [t] with listOf' arbitrary.

genericArbitrary with explicit generators.

Example

genericArbitraryG customGens (17 % 19 % ())

where, for example to override generators for String and Int fields,

customGens :: GenList '[String, Int]
customGens =
  (filter (/= '\NUL') <$> arbitrary) :@
  (getNonNegative <$> arbitrary) :@
  Nil

Note on multiple matches

If the list contains multiple matching types for a field x of type a (i.e., either a or Field "x" a), the generator for the first match will be picked.

genericArbitraryU with explicit generators. See also genericArbitraryG.

genericArbitrarySingle with explicit generators. See also genericArbitraryG.

genericArbitraryRec with explicit generators. See also genericArbitraryG.

General generic generator with custom options.

Run the first generator if the size is positive. Run the second if the size is zero.

defaultGen `withBaseCase` baseCaseGen

Custom instances can override the default behavior.

Trees of weights assigned to constructors of type a, rescaled to obtain a probability distribution.

Two ways of constructing them.

(x1 % x2 % ... % xn % ()) :: Weights a
uniform :: Weights a

Using (%), there must be exactly as many weights as there are constructors.

uniform is equivalent to (1 % ... % 1 % ()) (automatically fills out the right number of 1s).

Type of a single weight, tagged with the name of the associated constructor for additional compile-time checking.

((9 :: W "Leaf") % (8 :: W "Node") % ())

A binary constructor for building up trees of weights.

Uniform distribution.

Type-level options for GArbitrary.

Default options for sized generators.

Default options overriding the list generator using listOf'.

Default options for unsized generators.

Whether to decrease the size parameter before generating fields.

Heterogeneous list of generators.

A generator which overrides a specific field named s.

Available only for base >= 4.9.

Field constructor with the field name given via a proxy.

Generators for containers of kind * -> *, parameterized by the generator for each element.

Generators for unary type constructors that are not containers.

Generic Arbitrary

Derived uniform distribution of constructors for a.

An alternative to listOf that divides the size parameter by the length of the list. The length follows a geometric distribution of parameter 1/(sqrt size + 1).

An alternative to listOf1 (nonempty lists) that divides the size parameter by the length of the list. The length (minus one) follows a geometric distribution of parameter 1/(sqrt size + 1).

An alternative to vectorOf that divides the size parameter by the length of the list.