Tracks
/
Standard ML
Standard ML
/
Exercises
/
Flatten Array
Flatten Array

Flatten Array

Easy

Instructions

Take a nested list and return a single flattened list with all values except nil/null.

The challenge is to write a function that accepts an arbitrarily-deep nested list-like structure and returns a flattened structure without any nil/null values.

For Example

input: [1,[2,3,null,4],[null],5]

output: [1,2,3,4,5]

You can think of this data structure as a Rose Tree. You are given a data type 'a tree that represents this data structure.

Notes

  • For this exercise Empty represents null
  • The nested list is represented by List [...].
  • The input example is represented by List [Elem 1, List [Elem 2, Elem 3, Empty, Elem 4], List [Empty], Elem 5]
Last updated 29 June 2022
Edit via GitHub The link opens in a new window or tab
Standard ML Exercism

Ready to start Flatten Array?

Sign up to Exercism to learn and master Standard ML with 28 exercises, and real human mentoring, all for free.