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Range `for`

The general declaration of a for loop in C like for (init; condition; step) will be removed. Instead, for loops shall only (ONLY!) be used for range based loops:


    NAL:
    for (i in myArray) {...}
    for (i in [5 .. n]) {...}


    C:
    for (size_t i = 0; i < _nalArraySize(myArray); ++i) {...}
    for (size_t i = 5; i < n; ++i) {...}

Discussion

Syntax is similar to other languages like Python
Maybe even the round parantheses () can be removed? This is how it looks: for i in myArray {...}
i is always an index. If an actual value of an array needs to be addressed, one still needs to call the array operator (or however it is called).
More complex loops have to be programmed with while.

What is the type of the index variable?

While in C, the type size_t is commonly used, a keyword without underscore is preferred explicitely providing functionality for index counting. Proposition: idx, [], counter, sizet, tick

That type shall provide functionality to define an undefined index, like an over- and underflow. How is not yet solved.

Using the index variable outside of the loop

The index variable is always defined inside the loop. But sometimes, one wants to know the resulting index for use after the loop. In such a case, the retulting index will be returned from the for-loop like so:


    NAL:
    i32 lastIndex = for (i in [5 .. n]) {...}


    C:
    i32 lastIndex = 5;
    for (size_t i = 5; i < n; ++i) {
      ...
      lastIndex = (i32)i;
    }

If the break statement is used, the current value of the index variable will be returned:


    NAL:
    i32 lastIndex = for (i in [5 .. n]) {
      ...
      if(i == 20) { break; }
    }


    C:
    i32 lastIndex = 5;
    for (size_t i = 5; i < n; ++i) {
      ...
      if(i == 20) {
        lastIndex = (i32)i;
        break;
      }
      lastIndex = (i32)i;
    }

If desired, with a break statement, the programmer may return a custom index like so:


    NAL:
    i32 lastIndex = for (i in [5 .. n]) {
      ...
      if(i == 20) { break 111; }
    }


    C:
    i32 lastIndex = 5;
    for (size_t i = 5; i < n; ++i) {
      ...
      if(i == 20) {
        lastIndex = (i32)111;
        break;
      }
      lastIndex = (i32)i;
    }

Range for

Discussion

What is the type of the index variable?

Using the index variable outside of the loop

Range `for`