message: Expand float printing docs
diff: @@ -18,8 +18,6 @@ The floating point extension adds one new base type:
  Floating point numbers are 64-bit, double-precision [IEEE 754][] values.
  (There is no single-precision type.)
  -Floating point numbers are outputted with 17 decimal points of precision. Positive and negative zeros compare as equal but are distinct values when printed. Nan and Infinity are valid runtime values that are represented as `-Infinity`/`Infinity`/`NaN` respectively.
  -
  [IEEE 754]: https://en.wikipedia.org/wiki/IEEE_754
  Operations
  @@ -41,3 +39,11 @@ There are also comparison operators, which take two `float` values and produce a
  - `fle`
  - `fgt`
  - `fge`
  +
  +Printing
  +--------
  +
  +The [core `print` operation](./core.md#miscellaneous) prints `float` values with 17 decimal digits of precision, including trailing zeros.
  +(This is like using the `%.17lf` format specifier in C's `printf`.)
  +Positive and negative zero, while they are equal according to `feq`, look different when printed.
  +Not-a-number values are printed as `NaN`; infinite values are printed as the strings `Infinity` or `-Infinity`.
  