How to initialize Swift array with nil -

i trying have nil zeroth index element , rest have value of generic type t comparable.

so when initialise nil works expected

struct container<t: comparable> {     var container = [t?]()      init() {         container.append(nil)     } } 

but when integer 0, ambiguous reference

struct container<t: comparable> {     var container = [t?]()      init() {         container.append(0)     } }   playground execution failed: error: algorithms.playground:7:9: error: ambiguous reference member 'append'         container.append(0)         ^~~~~~~~~ 

i want understand why error occurring?

t can any comparable type (string, custom type, ...), , initializing 0 not possible.

you require t can created integer literal, covers integer , floating point types:

struct container<t: comparable> t: expressiblebyintegerliteral {     var container = [t?]()      init() {         container.append(0)     } }  

or provide separate append() method:

struct container<t: comparable> {     var container = [t?]()      init() {         container.append(nil)     }      mutating func append(_ newelement: t) {         container.append(newelement)     } }   var c = container<int>() c.append(0)