Validating Program Symbol Usage
To build an interpreter, compiler, or translator for a programming language such as Cymbol, weâd need to verify that Cymbol programs used symbols (identifiers) properly. In this section, weâre going to build a Cymbol validator that checks the following conditions:
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Variable references have corresponding definitions that are visible to them (in scope).
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Function references have corresponding definitions (functions can appear in any order).
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Variables are not used as functions.
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Functions are not used as variables.
To check all these conditions, we have a bit of work to do, so this example is going to take a little bit longer than the others to absorb. But, our reward will be a great base from which to build ...
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