Option

Option -- the class of all pairs x => y.

Such pairs are used as optional arguments for functions. There is also a way to make new hash tables with new by providing a list of option pairs.

     i1 = a => 5
     
     o1 = a => 5
     
     o1 : Option

     i2 = peek (a => 5)
     
     Option{a,5}

     i3 = new HashTable from {a => 5, b => 7}
     
     o3 = HashTable{a => 5}
                    b => 7
     
     o3 : HashTable

These pairs are implemented as lists, so that if z is x => y , then x is z#0 and y is z#1 .