Range Types

Why This Matters

Ranges are Arden's core numeric iteration primitive. You use them in loops, manual iteration, and simple numeric traversal without building lists first.

Quick Mental Model

range(start, end) -> values from start up to end (end-exclusive)
optional third arg is step
works with Integer and Float
step must be non-zero

Constructing Ranges

import std.io.*;

function main(): None {
    r1: Range<Integer> = range(0, 5);
    r2: Range<Integer> = range(0, 10, 2);
    rf: Range<Float> = range(0.0, 1.0, 0.25);
    println("constructed ranges");
    return None;
}

Manual Iteration (Runnable)

import std.io.*;

function main(): None {
    r: Range<Integer> = range(0, 5);
    while (r.has_next()) {
        value: Integer = r.next();
        println("value={value}");
    }
    return None;
}

Iteration contract:

has_next() tells you whether the current position is within configured bounds
next() advances and returns current value
next() itself does not enforce bounds; calling it after has_next() == false continues arithmetic progression

Example behavior:

range(0, 1) then repeated next() yields 0, 1, 2, ...
therefore, always gate next() with has_next() in bounded loops

In `for` Loops

import std.io.*;

function main(): None {
    for (i in 5) {
        println("i={i}");
    }
    return None;
}

for (i in 5) is shorthand numeric iteration and is often the cleanest option.

Descending numeric traversal:

import std.io.*;

function main(): None {
    r: Range<Integer> = range(10, 0, -2);
    while (r.has_next()) {
        println("v={r.next()}");
    }
    return None;
}

Common Mistakes

assuming end is included (it is excluded)
using zero step (range(0, 10, 0)) which is invalid
mismatching numeric kinds across arguments
using wrong step direction (range(0, 10, -1) starts with has_next=false)
calling next() after has_next() is already false

Control Flow
Example: 25_range_types