keep: Filter a series by keeping results that fulfill a predicate
In michaelquinn32/generators: Generators: Iterable functions

Filter a series by keeping results that fulfill a predicate

1	keep(.generator, .keep)

`.generator`	A function with the class `generator`
`.keep`	A predicate function, returning `TRUE` or `FALSE`

# Generate even numbers
counter <- generator(0, ~ state + 1)
counter %>%
  keep(~ state %% 3 == 0) %>% take(5)

# Combine a wrap and a counter
squares <- function(state) state ^ 2
counter %>%
  wrap(squares) %>%
  keep(~ state %% 3 == 0) %>%
  take(5)