Anything like C++ std::includes?

General Usage
9

Not sure if you had a and b swapped, and also the possible implementation did not seems to handle the case for the last element of b (first2!=last2) ?.

function includes(a::AbstractVector,b::AbstractVector)
    first2 = firstindex(b)
    last2 = lastindex(b)
    first1 = firstindex(a)
    last1 = lastindex(a)
    
    while first2 != last2
        if (first1 == last1) || (b[first2] < a[first1])
            return false
        else !(a[first1] < b[first2])
            first2 += 1
        end
        first1 += 1
    end
    first2 == last2 && return (b[first2] in a) 
    return true
end

v1 = ['a', 'b', 'c', 'f', 'h', 'x']
v2 = ['a', 'b', 'c']
v3 = ['a', 'c']
v4 = ['a', 'a', 'b']
v5 = ['g']
v6 = ['a', 'c', 'g']
v7 = ['A', 'B', 'C']

"""
$(v1)
includes:
a b c   : $(includes(v1, v2))
a c     : $(includes(v1, v3))
a a b   : $(includes(v1, v4))
g       : $(includes(v1, v5))
a c g   : $(includes(v1, v6))
\$v1     : $(includes(v1, v1))
""" |> print

Produce this, which is closer to the expected behavior.

['a', 'b', 'c', 'f', 'h', 'x']
includes:
a b c   : true
a c     : true
a a b   : false
g       : false
a c g   : false
$v1     : true

Edit:
Should be this instead.
first2 == last2 && return (b[first2] in a[first1:end])

['a', 'b', 'c', 'f', 'h', 'x']
includes:
a b c                : true
a c                  : true
a a b                : false
g                    : false
a c a                : false
a b c g              : false
a b c f h x          : true