Loops

Condition loop

The basic precondition loop is declared using the while keyword:

var a = 0
while a < 10 do
    println "{0}..." a
    a = a + 1

Iterator loop

To iterate over a list of values one can use the for loop:

let data = new [1; 2; 3; 4; 5]
for i in data do
    print "the value is {0}!" i

The same keyword can also be used to define a classic index loop:

for i in 1 .. 5 do
    print i

If the second boundary of the loop is smaller than the first, the index will gradually decrement instead of incrementing. The step is always equal to 1. To use a different step one might use the to extension method to construct a custom range of values.

Exiting the loop

Unlike many languages, LENS does not have break or continue keywords. There is no way to exit a loop prematurely or skip an iteration.

Return value

The loop can be used as an expression if passed to a function, placed at the right side of an assignment statement or as the last statement of a function. The result is the value of the loop's last line. If the loop has not run a single iteration, the default value is returned.

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• Conditions