Allow explicitly casting arrays to logicals

[szhorvat]

MCell can be used to explicitly cast an expression to a cell, i.e. force interpretation as a cell.

MFunction["class"][Range[5]]
"double"

MFunction["class"][MCell@Range[5]]
"cell"

It would be useful to add support to cast to logical arrays explicitly, i.e. MFunction["class"][MLogical@UnitStep@Range[-5,5]] should return "logical".

This is because some functions only take logical arrays. An example is bwdistgeodesic. Large logical arrays, e.g. ones that represent binary images, are just not practical to be represented as arrays of True and False. A packed integer array is much better.

It's been a long time. What do you think?

[rsmenon]

Yeah, this is definitely a good idea. Heh, we put it down as a todo but forgot :) (and seems like it wasn't missed much).

Since we're talking about large multidimensional arrays, perhaps we should avoid having to do ArrayQ[arr, testIfZeroOneIntegers] in the definition? I'm not sure if this would unpack. Perhaps something like MLogical[..., "Integer" -> True] and then we don't do Boole@ on it?

Either way, definitely a +1.