floats and range

[data-man]

const std = @import("std");
const it = @import("ziter.zig");

fn add(a: f32, b: f32) f32 { return a + b; }

test "f32, 0, 1, 0.1" {
	const result = it.range_ex(f32, 0, 1, 0.1)
	.call(it.fold, .{@as(f32, 0), add});
	std.debug.print("result = {}\n", .{result});
}

test "f32, 0, 1, 0.3" {
	const result = it.range_ex(f32, 0, 1, 0.3)
	.call(it.fold, .{@as(f32, 0), add});
	std.debug.print("result = {}\n", .{result});
}

test "f32, 0, 1, 0.1"... result = 4.5e+00 //correct test "f32, 0, 1, 0.3"... result = 1.80000007e+00 //incorrect

[Hejsil]

Ops, looked at this but forgot to respond. Isn't this just quirk of floating point numbers. Not really much this lib can do about that.

[data-man]

Is it possible to: not provide len_hint if a given type is some float?

And the related proposal: make range inclusive, like C++ std::iota.

[Hejsil]

Is it possible to: not provide len_hint if a given type is some float?

Not sure what you mean. Do you mean that range should not provide len_hint for floats?

And the related proposal: make range inclusive, like C++ std::iota.

I made it exclusive as it follows how slicing works in zig, so zig programmers are familiar with it.

[data-man]

Do you mean that range should not provide len_hint for floats?

Yes.

I made it exclusive as it follows how slicing works in zig

Ok. What about new pub fn range_i? (or similar name)

[Hejsil]

I see. Yea, both of these sounds good to be :+1:

[data-man]

Or to add new parameter to range_ex: comptime inclusive: bool?

[Hejsil]

Hmmmmm. How about:

pub fn range(comptime T: type, start: T, end: T, opts: struct { inclusive: bool = false, step: T = 1 }) Range(T) {
    return .{ .start = start, .end = end + (opt.step * @boolToInt(opt.inclusive)), .step = opt.step };
}
...

range(u8, 0, 6, .{});
range(u8, 0, 6, .{ .step = 2 });

Basically, having and options argument with all fields having default values.

[data-man]

How about:

Looks good! :+1:

range(u8, 0, 6, .{ .step = 2 });

What will happen for range(u8, 0, 255, .{ .step = 2 });?

[Hejsil]

What will happen for range(u8, 0, 255, .{ .step = 2 });?

Well, that would overflow with the current behavior. We could have an implementation that handles this, which might be nice, but it probably has a cost.

[Hejsil]

As of 0c2a668c31b20ffefcaa8e59f70f85b8df94eccb, ziter.range no longer supports floats and step has been removed in favor of:

ziter.range(u8, 0, 10)
    .step_by(2)