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 the generator for fields of type [t] with listOf' arbitrary instead of listOf arbitrary (i.e., arbitrary for lists).

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 the generator for fields of type [t] with listOf' arbitrary instead of listOf arbitrary (i.e., arbitrary for lists).

Equivalent to genericArbitrary' uniform.

genericArbitraryU' :: Gen a

N.B.: This replaces the generator for fields of type [t] with listOf' arbitrary instead of listOf arbitrary (i.e., arbitrary for lists).

genericArbitrary with explicit generators.

Example

genericArbitraryG customGens (17 % 19 % ())

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

customGens :: Gen String :+ Gen Int customGens = (filter (/= '\NUL') <$> arbitrary) :+ (getNonNegative <$> arbitrary) 

Note on multiple matches

If the list contains multiple matching types for a field x of type a (i.e., either Gen a or FieldGen "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.

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") % ()) 

Note: these annotations are only checked on GHC 8.0 or newer. They are ignored on older GHCs.

A binary constructor for building up trees of weights.

Uniform distribution.

Heterogeneous list of generators.

Custom generator for record fields named s.

Available only for base >= 4.9 (GHC >= 8.0.1).

FieldGen constructor with the field name given via a proxy.

Custom generator for the i-th field of the constructor named c.

Available only for base >= 4.9 (GHC >= 8.0.1).

ConstrGen constructor with the constructor name given via a proxy.

Custom generators for "containers" of kind Type -> Type, parameterized by the generator for "contained elements".

A custom generator Gen1 f will be used for any field whose type has the form f x, requiring a generator of x.

Custom generators for unary type constructors that are not "containers", i.e., which don't require a generator of a to generate an f a.

A custom generator Gen1_ f will be used for any field whose type has the form f x.

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.

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.

Type-level options for GArbitrary.

General generic generator with custom options.

Whether to decrease the size parameter before generating fields.

Default options for sized generators.

Default options overriding the list generator using listOf'.

Default options for unsized generators.

Generic Arbitrary

Derived uniform distribution of constructors for a.