Semantic Analysis Planning

Currently trying to think about how best to implement semantic analysis. I can’t lie, I am just getting back into this project, so I am rediscovering what I had previously written.I guess I have to start at the beginning. What is semantic analysis?

1. Type Checking   
   • Operations need to be with compatible data types   
   • One note to myself here is that I have reserved functions because it’s Scratch, so those need to have a designed store for their types2. Scope Resolution   
   • Make sure variables and functions are designed in the right parts of code   
   • I think this will cover imports too, but its worth thinking about   
   • Undeclared and redeclared variable checks
2. Function Call Validation   
   • I’ll have to go back and check if I accidentally covered that in the parser, but I believe this should go here
3. Flow Control   
   • Switch case validations, make sure fall through keywords and default cases etc. are all in valid places5. Reserved Keyword   
   • Check if variable and functions defined are conflicting with Katnip’s

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First I’m going to do symbol collection and scope resolution.
One important nuance I discovered was whether or not to enforce scope declaration. Should there be an inferred scope?
In Scratch, this inferred scope is mostly ‘Public’, as variables are shared across sprites. However, I think I am going to flip this, as it feels wrong to teach the user that variables work across sprites.

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Thought dump:

• ‘Private’ kward can’t be used at root level (stage). Can’t be used as modifier for sprite either, tho neither should any modifier.
• Scope-less definitions are okay. Scratch does this, just opposite of me.
• I am going to raise function declarations so that they can be referenced before making. Requires 2 passes, but seems simpler and more intuitive in my opinion.
• I am going to allow function overloading. It seems useful, and I like the way Java does it.