F# Core Types

Besides the primitive types, the F# library includes several core types that will allow you to organize, manipulate and process data

Unit

The unit type is a value signifying nothing of consequence. unit can be thought of as a concrete representation of void and is represented in code via ():

> let x=();; val x : unit=() > x;; val it : unit()

if expres­sions without a matching else must return unit because if they did return a value, what would happen if else was hit?

Also, in F#, every function must return a value, think method in C# and the void return type, so even if the function doesn’t conceptually return any­thing then it should return a unit value.

The ignore function can swallow a function’s return value if you want to return unit:

> let square x=x*x;; val square :int->int > ignore (square 3);; val it : unit=()

Tuple

A tuple (pronounced two-pull) is an ordered collection of data,easy way to

group common pieces of data together. For example, tuples can be used to track

the intermediate results of a computation.

To create an instance of a tuple, separate group of values with comma, and optionally

place them within parentheses. Letz have fullName as an instance of a tuple, while

string * string is the tuples type:

> let fullName = ("ganesan", "senthilvel");; val fullName : string * string = ("ganesan", "senthilvel")

Tuples can contain any number of values of any type. You can have a tuple that

contains other tuples.