Swift Compiler performance

Question

I got this statement in Swift code which produces an error when executing in playground:

let colors: [String: [Float]] = ["skyBlue" : [240.0/255.0, 248.0/255.0, 255.0/255.0,1.0], 
"cWhite" : [250.0/255.0, 250.0/255.0, 250.0/255.0, 1.0]]

The error is : expression was too complex to be solved in reasonable time; consider breaking up the expression into distinct sub-expressions

Then I changed the arrays element type to Double which just works fine.

However I am asking myself why this happens ? As I said using Double it works just fine. So my guess is that Swift tries to guess the type and therefore Double works better in this example than Float.

Answer 1

Similar issues have been reported before, and (as I understand it) the problem is the automatic type inference for "complicated" expressions. You should file a bug report at Apple.

It compiles with a dictionary of one color, but not with two.

In this concrete case, you can work around it by converting each number in the array to a Float explicitly:

let colors = [
    "skyBlue" : [Float(240.0/255.0), Float(248.0/255.0), Float(255.0/255.0),Float(1.0)], 
    "cWhite" : [Float(250.0/255.0), Float(250.0/255.0), Float(250.0/255.0), Float(1.0)]
]