all2 : : ('a -> 'b -> bool) -> 'a list -> 'b list -> bool

SYNOPSIS

Tests whether a predicate holds pairwise throughout two lists.

DESCRIBE

all2 P [x1,...,xn] [y1,...,yn] equals P x1 y1 andalso .... andalso P xn yn. all2 P [] [] yields true.

FAILURE

If P x0,...,P x(j-1} all evaluate to true and P xj raises an exception e, then all2 P [x0,...,x(j-1),xj,...,xn] raises e. An invocation all2 P l1 l2 will also raise an exception if the length of l1 is not equal to the length of l2.

EXAMPLE

    - all2 equal [1,2,3] [1,2,3];
    > val it = true : bool

    - all2 equal [1,2,3] [1,2,3,4] handle e => Raise e;

    Exception raised at Lib.all2:
    different length lists
    ! Uncaught exception: 
    ! HOL_ERR

    - all2 (fn _ => fn _ => raise Fail "") [] [];
    > val it = true : bool

    - all2 (fn _ => fn _ => raise Fail "") [1] [1];
    ! Uncaught exception: 
    ! Fail  ""

SEEALSO  Lib,   all