Variable declaration in Swift REPL must have initial value

Question

Studying Swift grammar declaration of closure. I'm having a problem with:

let add: (Int, Int) -> Int 
add = { (a: Int, b: Int) -> Int in
    return a + b
}

error:

variables currently must have an initial value when entered at the top level of the REPL var add: (Int, Int) -> Int

Gerriet · Accepted Answer · 2019-01-18 18:09:09Z

1

Swift does not have separate variable declarations without assignments (assigning nil to an optional would be the closest thing), so the easiest fix would be:

let add: (Int, Int) -> Int = { (a: Int, b: Int) -> Int in
   return a + b
}

As correctly pointed out by the commenters and as noted in the error message, my claim is only true at the top level of the Read-Eval-Print-Loop (REPL).

edited Jan 18, 2019 at 18:09

answered Jan 18, 2019 at 6:20

Gerriet

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2 Comments

Sulthan Over a year ago

This is not completely true. Swift does have separate variable declarations without assignment. You just cannot do that at the top level. You could do that without problems in a console application or in a function.

jscs Over a year ago

This applies only to the REPL. Perfectly legal: gist.github.com/woolsweater/503c12cd91b9e9573e0ddadec7b02c0d

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