Usage of `:` in different contexts may be confusing

[fridis]

Problem

Fuzion uses : for a number of very different purposes:

1. to separate a feature signature from its inheritance calls f32(public val f32) : float is
2. to create anonymous features ref : Any ...
3. to define a constraint on a type parameter f(T type : numeric)
4. as the implies operation in bool.infix :
5. to construct a simple list h : tail
6. to separate the middle and the last argument in the ternary operator ? :

This might confuse the user since a : b could mean completely different things.

Other languages

What are the alternatives? Here is what I found in other languages

1. inheritance:
   • C++: class child : parent { ...
   • Java: class child extends parent { ...
   • Eiffel: class child inherit parent ...
2. anonymous features
   • Java: nothing: new Object() { }
3. type parameter constraint
   • Java uses T extends Comparable<? super T>
4. boolean implies
   • C, Java, C++, Python: use !a || b
5. add element to head of list
   • Haskell: x : xs
   • Ocaml: x :: xs
6. ternary operator
   • C, Java, C++: a ? b : c
   • Python: b if a else c

Possible alternatives

1. stick with : or use inherits
2. require is as in Any is ...
3. stick with : or use f(T type inherits numeric) or f(T inherits numeric)
4. unicode U+21D2: debug ⇒ 0 <= i < size
5. use Ocaml's h :: tail, but what about Fuzion's 1 :: +1?
6. unify ternary operator and match expression using a ? b | c.

Any commens, suggestions?

[michaellilltokiwa]

I very much agree with the problem. I don't see an issue with having a keyword inherits and don't mind the additional typing in this case. So this is what I would prefer currently.

[maxteufel]

I personally don't mind any of this, and don't find it confusing. There are features in the base library that I mix up more often than this.

[simonvonhackewitz]

I personally don't like alternative 4, using ⇒ for the pre-/postcondition qualifiers, because it looks similar to a feature declaration and can not simply be typed on the keyboard. Other than that I have no strong opinion on this.