Proposal: Distributive Logical Operators

[alrz]

Using #6235 you can match an expression to a set of patterns like,

if(expr is Pattern1 or Pattern2)
if(expr is Pattern1 and Pattern2)

This issue proposes to use same set of operators in the lhs of is operator,

if(expr1 or expr2 is Pattern)
if(expr1 and expr2 is Pattern)

For example,

a or b is 5
a == 5 || b == 5

a and b is 5
a == 5 && b == 5

We can use both at the same time,

a or b is 1 or 5
(a == 1 || a == 5) || (b == 1 || b == 5)

a and b is 1 or 5
(a == 1 || a == 5) && (b == 1 || b == 5)

a and b is T
a is T && b is T

a is T or U
a is T || a is U

If the lhs contains an and operator, you can't use variables in your pattern, e.g.

if(a and b is T x) 

is illegal.