@swift-ci create

This is a well-known type checker performance issue. If you wait long enough, you'll get this error: error: the compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions

As the error message states, the workaround is to break up the sequence of literals and operators into smaller expressions, which will be type checked separately:

var eq2 = 1.0 - 1/3.0 + 1/5.0
var eq3 = eq2 - 1/7.0

You could also help the type checker out by adding more explicit types into the source code. For example, this code:

var eq3 = 1.0 - Double(1/3.0) + Double(1/5.0) - Double(1/7.0)

compiles just fine.