Old, Discarded Ideas

For several topics there are alternative ideas, that were discarded but are still worth mentioning.

Trailing Semicolons

• We could keep the trailing semicolons for now.
• Disadvantages of not having trailing semicolons:
  • Errors are less easily recognized. (Walter Bright / D: „Redundancy helps“)
  • Probably a completely new parser must be written, as the one from clang (for C++) no longer fits at all.
• Implicitly/clever multiline expressions as in Swift, Kotlin and JavaScript?
  (Actually I don’t know / remember the rules anymore.)

Better Readable Keywords

• Instead of class ... : ... Cilia could have
  • class ... extends ...
    • good for extending base classes
  • class ... implements ...
    • good fit for implementing pure abstract base classes (like interfaces)
• But then we would have two different keywords. And what about mixed cases, i.e. abstract classes with partly function implementation? (Probably best to use implements then, but still not nice.)

Basic / Arithmetic Types

• Float could be 32-bit float: Float == Float32,
  • like in C++.
  • Then Float == Float32 on all platforms.

Variable Declaration

• Very short variable declaration:
  • Maybe possible to simply write i = 3?
  • Maybe i := 3?
• let i = 0 instead of const i = 0
  • similar to Swift and Carbon.
  • In Rust let mut is used for variables,
  • in JavaScript let and const are very similar with slight differences.
• Always starting with keyword var
  • Examples:
    • var Int i
    • var i : Int
  • In case func for function declaration, but not var for variable declaration, is still not clear enough.
  • Swift, Kotlin and Circle always start variable declarations with var.
  • Not starting with var could be especially problematic in connection with omitting the trailing semicolons.

Bitfields

One could define the order of bits in a bitfield.

• MSB (Most Significant Bit) first.
  • This way you can use

    class Float32Equivalent {
        UInt32:1  signIsNegative
        UInt32:8  exponent
        UInt32:23 significand // AKA mantissa
    }
    

    to read/interpret Float32,

  • and with

    class SignBitOfInt64 {
        UInt64:1 signIsNegative
    }
    

    signIsNegative is true for negative Int64.

  • Bits are left-aligned, so the first element always covers the most-significant bit:

    class MostSignificantThreeBits {
        UInt8:1 bit7
        UInt8:1 bit6
        UInt8:1 bit5
        // ...
    }
    

  • This is what typical “MSB-first” C++ compilers do (on big-endian PowerPC, MIPS, SPARC).
    • CiliaC may have to reverse the order of bit field elements and add some padding UInt32:... __filler_for_right_alignment (when using typical “LSB-first” C++ compilers like GCC x86).
  • Add your own filler (padding bits) to shift field elements/members on demand, e.g.

    class Sign {
        UInt32:1  filler
        UInt32:31 bit0
    }
    

Functions

• Function declarations could start with the keyword
  • fn (Rust, Carbon, New Circle),
  • fun (Kotlin), or
  • function (Julia)
• Extension methods
  • Possible, alternative syntax:
    func toString (Int this) -> String
• Function pointers
  • Possible, alternative syntax variants:
  • Variant B:
    • func((Int, Int) -> Int)* pointerToFunctionOfIntAndIntToInt // Closer to the function declaration but (too) many brackets
  • Variant C:
    • (Int, Int -> Int) [Functions are only available as pointers, so you can omit “*”?]
  • Variant D:
    • func*(Int->Int) pointerToFunctionOfIntAndIntToInt
    • func*(Int) pointerToFunctionOfInt
  • Variant E:
    • func*(Int, Int)->Int pointerToFunctionOfIntAndIntToInt
    • (func*(Int, Int)->Int)[] arrayOfPointersToFunctionOfIntAndIntToInt

Function/Loop Parameter Passing

• If you want even the basic type to be different, we could write:
  • for Double d in [1, 2, 3] { ... }
    • d is const Double
  • for String str in ["a", "b", "c"] { ... }
    • str is const String (not const StringView&)
    • str is const String& (not const StringView&)
      • TODO This doesn’t actually make sense here; you cannot get a (const) reference to a string when the underlying array is in fact a StringView[].
  • for inout String str in ["a", "b", "c"] { ... }
    • str is String&
    • TODO This doesn’t actually make sense here; you cannot get a (mutable/non-const) reference to a string when the underlying array is in fact a StringView[].
  • for copy String str in ["a", "b", "c"] { ... }
    • str is String

Switch/Case

• Old behavior with implicit fallthrough on demand.

  switch i fallthrough {
  case 1:
  case 2:
  case 3:
  case 4:
  case 5:
      print("1, 2, 3, 4, or 5")
      break
    
  default:
      print("default")
  }
  

Literals

• true, false are Bool
• Null could be the null pointer, and NullType its type.
  • Shorter and more similar to NULL in C.

Signed Size

• UInt as type for *.size() (i.e. still unsigned)
  but with new rules for mixed integer arithmetic:
  • Unsigned +-*/ Signed -> Signed.
    • Signed is therefore considered the “larger” type compared to unsigned
    • 1 is Int (signed)
      • 1u is UInt (unsigned)
    • Therefore if aUInt - 1 >= 0 is a useful expression (as 1 is signed, aUInt - 1 is signed, too)
    • But then also aUInt + 1 == anInt
• Or
  • Size - Size -> SSize
    • Problem: - results in SSize, but + results in Size?!
  • The conversion of a negative number into Size leads to an error instead of delivering a HUGE size.
• Note: In the end this just didn’t work out.

Operators

• Possible, alternative syntax for pow(a, x):
  a**x (as Python did)
• Some more kinds of range literals could be useful:
  • 8>..0:-1 – 7, 6, 5, 4, 3, 2, 1, 0
    • RangeExclusiveStartByStep(8, 0, -1)
  • 8>..0:-3 – 7, 4, 1
    • RangeExclusiveStartByStep(8, 0, -3)
  • 8..>0:-1 – 8, 7, 6, 5, 4, 3, 2, 1
    • RangeExclusiveEndByStep(8, 0, -1)
  • 8..>0:-1 – 8, 7, 6, 5, 4, 3, 2, 1
    • RangeDownwardsExclusiveEndByStep(8, 0, -1)
  • Incomplete ranges
    • 0<.. – RangeFromExclusiveStart(0)
  • Incomplete range with step
    • 8>..:-1 – RangeFromExclusiveStartByStep(8, -1)
    • 8>..:-2 – RangeFromExclusiveStartByStep(8, -2)
  • 0<..2 – RangeExclusiveStart(0, 2)
  • Range with negative step used for downwards iterating ranges:
    • 2..0:-1 – RangeWithStep(2, 0, -1)
    • 3>..0:-1 – RangeExclusiveStartWithStep(3, 0, -1)
    • Incomplete ranges with negative step:
      • ..1:-1 – RangeToWithStep(1, -1)
      • 2..:-1 – RangeFromWithStep(2, -1)
      • 3>..:-1 – RangeFromExclusiveStartWithStep(3, -1)
      • ..:-1 – RangeFullWithStep(-1)
  • Note: Too complicated for too little benefit.
• Maybe remove ++i, --i, i++, i--?
  • as Python
  • only offer/allow i += 1, i -= 1
    or even only i = i + 1, i = i - 1
  • Note: No, Cilia is a C++ descendant after all.

Templates

• Class templates
  • Partial template specialization could be written

    class<type T, Int N> MyUniquePtr<T[N]> {
        ... destructor calls delete[] ...
    }
    

• Function templates
  • Explicit function templates could be written as: func<Number T> add(T x, y) -> T { return x + y }
  • Extension function templates could be written as
    • template<type T, Int N> func T[N]::size() -> Int { return N }
    • template<type T, Int N> func T[N]::convertTo<type TOut>() -> TOut[N] { ... }
• Template type alias could be written as:
  • template<type T> using T::InArgumentType = const T&

Cilia Standard Library

• “Alias” for
  • member variables could be written as
    alias x = data[0],
  • member functions could use perfect forwarding,
    • see stackoverflow.com/a/9864472
    • but that would not work for virtual functions.

String, Char & Unicode

• Code points could be represented by UInt32 or by a distinct type CodePoint (== UInt32).
  • Would it be useful?
• WideChar could be useful for portable code (Linux UInt32 <-> Windows UInt16)
  • But you may use wchar_t then.
• Alternative names/syntax to iterate over strings:
  • for codeUnit in "abc 🥸👮🏻".asCodeUnits() (a bit more explicit/clear than .asArray())
  • Is byWord() (like in “word by word”) a better naming?
    • for graphemeCluster in text.byGraphemeCluster()
    • for codePoint in text.byCodePoint()
    • for codeUnit in text.byCodeUnit()
    • for codeUnit in text.byChar()
    • for word in text.byWord()
    • for line in text.byLine()
    • for sentence in text.bySentence()

Arrays & ArrayViews

• Int[] dynamicArrayOfIntegers
  • Also the syntax [T] arr, as in Swift or Rust, has some merits.
    And [3 T] arr for fixed sized arrays would be fine for me (I don’t like [T;3] arr), but I’ll stick with the more traditional T[] arr (like C# and Java).
  • May be confusing because it is so similar to fixed-size arrays,
    but IMHO the inconsistency is already in C/C++:
    • in function declarations
      • int[] and int* are actually the same,
    • but for local variables
      • int[] and int* mean different things:
        • int array[3] and int array[] = { 1, 2, 3 } are used for in-place arrays,
        • int* array = new int[3] is used for an int-array of unknown size.
• Mixed forms of static and dynamic array may be useful:
  • Int[3,,]
  • Int[3,4,]

(Smart) Pointers

• We may use some more (or just other) characters for the “special” pointers
  • ASCII
    • Type> pointer (very difficult to read with template types, e.g. Matrix<Float64>> matrix)
    • Type~ pointer (also used for binary not and destructor syntax)
    • Type# pointer
    • Type% pointer
    • Type§ pointer
    • Type$ pointer
    • Type' pointer
    • Type. pointer
  • More exotic characters
    • (But a character that is difficult to find on the keyboard would not actually encourage people to use this syntax.)
    • Latin-1
      • Type° pointer
      • Type¹ pointer
      • Type• pointer
      • Type› pointer
    • Unicode variants of T*
      • Type*̂ pointer
      • Type*̄ pointer
      • Type*̇ pointer
      • (easy to confuse with T*)
  • * plus other character(s)
    • (a bit long)
    • Type*^ pointer
    • Type*+ pointer
    • Type*. pointer
    • Type*° pointer
    • Type*¹ pointer
    • Type*+ pointer
    • Type*> pointer
    • Type*1> pointer
    • Type*¹> pointer
    • I don’t like this:
      • Type^* pointer
      • Type+* pointer
      • Type.* pointer

is, as, Casting

• Automatic casts
  • As multiple inheritance is problematic here:
    • In Cilia/C++, an object can be an instance of several base classes at once, whereby the pointer (sometimes) changes during casting.
    • What if you still want/need to access the functions for a Type obj after if obj is ParentA?
    • Therefore maybe better: if obj is String str ...
      • as in C#

C++ Compatibility / Interoperability

The compiler recognizes the language (C, C++, or Cilia) by marked blocks:

• lang "C++" { ... }
• lang "Cilia" { ... }
• lang "C" { ... }
• Could be lLimited to top level.
• Could be extended to other languages as well, but technically this is limited to languages where the scope is marked with { }.

Versioning

Versioning of the Cilia source code could alternatively be done

• via file “.cilia_version” in a (project) directory,
• via file extension:
  • “*.cilia2024” – Version from the year 2024
  • “*.cilia2024b” – Second version from the year 2024
  • “*.cilia_2024” – Version from the year 2024
  • “*.cilia_2024b” – Second version from the year 2024
  • “*.ciliaA”
  • “*.ciliaB”