Casts: Value / Numeric Types
There are basically two kinds of type casts. First, those that change the
static type of an expression or reference type but do not change the value itself
only the way it is handled by the compiler.
(In Java the are implemented by the
checkcast bytecode with
the possibility to throw a runtime exception.)
Second, type conversions such as
(float) Math.PI that may
change the value they operate on (as to a lower precision value in this case).
Casts in other Languages
Scala has implicit conversion functions: Scala Implicit Conversions.
Java has implicit conversions for numeric types, requires explicit conversions if precision could get lost. No other implicit or explicit conversions are supported, these must be done via dedicated methods.
Go? Rust? Python?
Casting Values in Fuzion
Idea: use a postfix operation
as type as follows
i i32 := 1234567890 l i64 := i as i64 f f32 := i as f32 d f64 := i as f64 s i16 := i as i16
and implement them in the corresponding features, in this case in
i32 is [..] native as i16 auto native as i64 auto native as f64 [etc.]
For casts that do not lose information such as
f64, a modifier
auto indicates that the compiler
can call these automatically to make sure values are assignable, i.e., the
example above can be simplified as follows
i i32 := 1234567890 l i64 := i // i32.as i64 implicitly called f f32 := i as f32 d f64 := i // i32.as f64 implicitly called s i16 := i as i16
TBW: What syntax is used in Python/F#/Nim/etc.?