λ Tony's Blog λ

I have found that...

Posted on March 23, 2010

I have found that many classes are created for the specific purpose of a sequence function in the ((->) t) monad, particularly in Java, C# and Python. Create a class, with a constructor that takes an argument (t) so that one may call many of its methods, each of which has access to t.

sequence :: [m a] -> m [a]
sequence* :: [t -> a] -> t -> [a]

If we consider the type of t which we shall call Swizzle and the created class we shall call SwizzleManager then

// A constructor accepting a Swizzle
SwizzleManager m = new SwizzleManager(t);
// One of the following usually follow:
//   A list constructed by the results of executing several methods on 'm'
List<r> = { m.a(x), m.b(y), m.c(z) }
//   A loop over a list of the results of executing several methods on 'm'
for(R r : { m.a(x), m.b(y), m.c(z) }) {
//   A list of effects to execute using 'm'