[ukj]

You are over-complicating this into obscurity.

General case: Validating random data as input into some program.

Particular case: Validating random source code (data) as input into some compiler (program).

Do compilers parse or validate?

"parsing is validation, but validation is not parsing" if that were true then you should be able to give an example of a compiler doing some sort of validation on the random source code (data) that is not parsing.

The very thing which determines the validity of random source code is the compiler's ability to parse it.

[codetrotter]

But I’m not talking about compilers here

[ukj]

Why not?

Compilers are computable functions.

If “Parsing is validation, but validation is not parsing” is true then it is also true about compilers.

[jhgb]

> If “Parsing is validation, but validation is not parsing” is true then it is also true about compilers.

This is a false statement, considering that the cases where something is validation but not parsing may very well lie in the complement of the set of compilers to the set of all computable functions. The converse statement that if this were true about the smaller set (of compilers), it would also be true about the larger set (of all programs) would on the other hand be correct.