Number text

import std.number_text. The numbers std.io prints have an overload each. These do not, and this module is what prints them: an integer wider than 64 bits, and the four floats other than Float.

Integers wider than 64 bits

print, println, toString, as String and string interpolation ("${x}") accept an Int<N> or UInt<N> of any width once the file imports this module. Up to 64 bits they need no import, since the value converts to I64 or U64 first.

import std.io
import std.number_text

fn main() -> Int {
    let min: Int<128> = -170141183460469231731687303715884105728
    let top: UInt<256> = 1
    println(min)
    println(top << 255)
    return 0
}

-170141183460469231731687303715884105728
57896044618658097711785492504343953926634992332820282019728792003956564819968

toString(radix) is not available past 64 bits. The call is rewritten to intText(value, bits, signed), a generic function that takes the value apart in 32-bit digits and divides by 10^9, so nothing here needs a 128-bit division from the platform's runtime. It is quadratic in the width.

F16, F32, BF16 and F128

print, println, toString() and toString(decimals) are overloaded for each.

toString() and print write the fewest digits that read back as the same number in the same type. An F32 written 0.1 prints 0.1; printing its widening to a double would show 0.10000000149011612, digits the type never had. F16 needs at most 5 digits, BF16 4 and F32 9.

import std.io
import std.number_text

fn main() -> Int {
    let third: F32 = 1.0
    println(third / 3.0)
    let h: F16 = 60000.0
    println(h * 2.0)
    return 0
}

0.33333334
inf

toString(decimals) formats a fixed-point column, after widening to a Float. An F128 prints as the Float nearest it, so a value that needs more than 17 digits is shown to 17.

Why a separate import

A call into a module is allowed only from a file that imports it, and these types are used by few programs. The overloads belong beside Float's in std.io and std.string, and move there once the bootstrap seed can read the type names; until then this module carries them.