Module CCRandom

return x is the generator that always returns x. Example: let random_int = return 4 (* fair dice roll *).

flat_map f g st is f (g st) st.

Monadic bind.

map f g st is f (g st).

Delay evaluation. Useful for side-effectful generators that need some code to run for every call. Example:

      let gensym = let r = ref 0 in fun () -> incr r; !r ;;

      delay (fun () ->
        let name = gensym() in
        small_int >>= fun i -> return (name,i)
      )

• Since: 0.4

Choose a generator within the list.

Like choose but without option.

• Raises Invalid_argument: if the list is empty.

Choose a generator within the array.

Choose among the list.

• Raises Invalid_argument: if the list is empty.

replicate n g makes a list of n elements which are all generated randomly using g.

sample_without_replacement n g makes a list of n elements which are all generated randomly using g with the added constraint that none of the generated random values are equal.

• Raises Invalid_argument: if n <= 0.
• Since: 0.15

Build random lists from lists of random generators.

• Since: 0.4

Pick an element at random from the list.

• Raises Pick_from_empty: if the list is empty.
• Since: 0.16

Pick an element at random from the array.

• Raises Pick_from_empty: if the array is empty.
• Since: 0.16

A small int (100).

Random int within the given range.

Inclusive range.

A reasonably small float (100.0).

• Since: 0.6.1

Random float within the given range.

• Since: 0.6.1

Inclusive range. float_range a b assumes a < b.

• Since: 0.6.1

Split a positive value n into n1,n2 where n = n1 + n2.

• Returns None if the value is too small.

Split a value n into a list of values whose sum is n and whose length is length. The list is never empty and does not contain 0.

• Raises Invalid_argument: if len <= 1.
• Returns None if the value is too small.

retry g calls g until it returns some value, or until the maximum number of retries was reached. If g fails, then it counts for one iteration, and the generator retries.

• Parameter max: : maximum number of retries. Default 10.

try_successively l tries each generator of l, one after the other. If some generator succeeds its result is returned, else the next generator is tried.

a <?> b is a choice operator. It first tries a, and returns its result if successful. If a fails, then b is returned.

Recursion combinators, for building recursive values. The integer generator is used to provide fuel. The sub_ generators should use their arguments only once!

• Parameter sub1: cases that recurse on one value.
• Parameter sub2: cases that use the recursive gen twice.
• Parameter subn: cases that use a list of recursive cases.

Using a random state (possibly the one in argument) run a generator.