Fix kernel function parameters

This MR implements equality and hashing for PsSymbol such that the parameters of KernelFunctions are unique.

Also improves some error messages.

requested review from @da15siwa

assigned to @he66coqe

added 1 commit

• f5ef2d89 - fix lint and static type check

Compare with previous version

Content-based equality and hashing for PsSymbol were not implemented intentionally to make sure that for every symbol, only one instance ever exists in the backend, and all symbol instances are known to and managed by the KernelCreationContext.

This is necessary so that changes to a symbol in one place (e.g. setting or updating the data type) are immediately reflected across the AST. If we allow multiple instances of PsSymbol to refer to the same object, the PsSymbol cannot be mutable, and a lot of transformations become harder to implement.

The KernelCreationContext acts as a symbol table; as long as you stick to using its interface (i.e. get_symbol), you should never get symbol duplicates.

Thanks for the explanation. Now I remember reading that in the documentation ^^

closed