CODEWITHSUNDEEP
scala
Priyan Chandrapala
Priyan Chandrapala

Reputation: 83

Multiple inserts to the same instance of an immutable data structure in Scala

I have a data type called Fork which is immutable. A Fork instance can include one or many instances of another data type Body. I want to insert a list of Body instances into the same Fork instance one by one. After each insertion of a Body, a new instance of Fork will be returned.

I have tried the following code but it gives an error. 

bodies: Seq[Body] // this is from the constructor 
val fk = Fork(nw, ne, sw, se) // new instance of a Fork is created 
val fkl = bodies.map(b => { val fk: Fork = fk.insert(b) }) // trying to 
// insert a list of Body instances to the same instance of Fork

Error:(131, 46) forward reference extends over definition of value fk
        val fkl=bodies2.map(b=>{ val fk:Fork=fk.insert(b)})

Upvotes: 1

Views: 41

Answers (1)

Nazarii Bardiuk
Nazarii Bardiuk

Reputation: 4342

You could use foldLeft

val fkl = bodies.foldLeft(fk)((f,b) => f.insert(b))

it will start with original fk instance and then for each body b will insert body into fork and return updated fork

Upvotes: 4

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