Fuzion • Tutorial • Numeric Constants

Numeric Constants

In the Fuzion base module, all numeric types inherit from type numeric. This includes basic types like i32, f64, but also composed types like num.fraction or num.complex.

To simplify numeric operations in code that is type parametric for any numeric type, integer constants can be used as values of a parametric type that is constrained by numeric. The followiwng example shows how this is used to create the constant 23 representation for different numeric types.

Internally, numeric constants are just syntax sugar for a call to from_u32 on the numeric type parameter using the constant as an argument, so the example above is equivalent to

This works not only for numeric types from the Fuzion base module, but as well for user defined numeric types. The following code defines an integer type for modulo 7 arithmetic. It inherits from integer, which itself inherits from numeric:

get23(N type : numeric) N => { 23 }

# type for integer modulo 7 arithmetic
mod7(val u8) : integer
  pre
    0 <= val < 7
is
{
  public redef fixed type.zero mod7 => { mod7(0); }
  public redef fixed type.one  mod7 => { mod7(1); }
  public redef fixed type.lteq(a,b mod7) bool => { a.val <= b.val; }
  public redef fixed infix +  (b   mod7) mod7 => { mod7((val+b.val)%7); }
  public redef fixed infix -  (b   mod7) mod7 => { mod7((val-b.val)%7); }
  public redef fixed infix *  (b   mod7) mod7 => { mod7((val*b.val)%7); }
  public redef fixed infix /  (b   mod7) mod7 => { mod7( val/b.val   ); }
  public redef fixed infix %  (b   mod7) mod7 => { mod7( val%b.val   ); }
  public redef as_string String => { "$val (mod 7)"; }
}

say <| get23(mod7)

What are effects?

last changed: 2025-12-17

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