F# while loop

In F#, a while loop allows us to execute a block of code repeatedly while a condition is true. The while loop is a fundamental looping structure in F# that allows us to iterate over a block of code based on a condition.

Syntax

The syntax of the while loop in F# is as follows:

while condition do
    // code block
    // this block will be executed repeatedly while the condition is true
done

Here, the condition is the expression that is evaluated at the beginning of each iteration. If the condition is true, the code block following the do keyword will be executed. This process is repeated until the condition becomes false.

Example

let mutable count = 0
while count < 5 do
    printfn "count = %d" count
    count <- count + 1
done

In the above example, we are using a while loop to print the value of count on each iteration. The loop will count up to 5, starting from 0.

Output

count = 0
count = 1
count = 2
count = 3
count = 4

Explanation

In the above example, we have declared a mutable variable count and initialized it with the value of 0. We then use a while loop to check if the value of count is less than 5. If it is, then we print the value of count. We then increment the value of count by 1.

This process continues until the value of count becomes greater than or equal to 5. At this point, the loop exits and the program execution continues.

Use

The while loop can be used in many cases where we need to execute a block of code repeatedly based on a condition. For example, we can use a while loop to read data from a file until the end of the file is reached.

Important Points

• The condition expression in the while loop is evaluated at the beginning of each iteration.
• If the condition is false at the beginning of the loop, the code block will not be executed at all.
• It is important to remember to update the condition inside of the loop, otherwise it may result in an infinite loop.

Summary

In summary, the while loop is a fundamental looping structure in F# that allows us to iterate over a block of code based on a condition. It is useful for repeating a set of statements while a condition is true. When using the while loop, make sure to update the condition inside the loop to avoid an infinite loop.