gen_element: Choose values or generators

In s7contract: Behavioral Contracts and Generative Laws for 'S7'

Choose values or generators

Description

gen_element() samples one element of a vector or list. gen_choice() samples a generator and draws from it at the current size. All choices are available at size zero. Both shrink toward earlier entries, then gen_choice() shrinks within the selected generator. Zero-weight entries are excluded from both generation and shrinking.

Usage

gen_element(values, prob = NULL)

gen_choice(..., prob = NULL)

Arguments

values	Non-empty atomic vector or list of values.
prob	Optional finite non-negative sampling weights, one per entry, with at least one positive weight.
...	One or more generators, ordered from simpler to more complex.

Value

An S7 generator object. gen_element() preserves an atomic input's element prototype; list inputs use a list prototype. gen_choice() retains a common prototype when all branches agree, otherwise it uses list elements.

Examples

bases <- gen_element(c("A", "C", "G", "T"))
nullable <- gen_choice(gen_constant(NA_integer_), gen_integer(), prob = c(1, 9))
gen_example(gen_vector(bases, min = 4L, max = 4L))

s7contract documentation built on Sept. 10, 2026, 1:09 a.m.