What is the OCaml idiom equivalent to Python's range function?
There is no idiom that I know of, but here is a fairly natural definition using an infix operator:
# let (--) i j = let rec aux n acc = if n < i then acc else aux (n-1) (n :: acc) in aux j [] ;;val ( -- ) : int -> int -> int list = <fun># 1--2;;- : int list = [1; 2]# 1--5;;- : int list = [1; 2; 3; 4; 5]# 5--10;;- : int list = [5; 6; 7; 8; 9; 10]Alternatively, the comprehensions syntax extension (which gives the syntax [i .. j] for the above) is likely to be included in a future release of the "community version" of OCaml, so that may become idiomatic. I don't recommend you start playing with syntax extensions if you are new to the language, though.
With Batteries Included, you can write
let nums = List.of_enum (1--10);;The -- operator generates an enumeration from the first value to the second. The --^ operator is similar, but enumerates a half-open interval (1--^10 will enumerate from 1 through 9).