Status quo: We have `force$Type` and `eval$Type`, both which first
produce a value and then do a type check. The type checking logic is not
consistently implemented, with lots of code duplication.
This change does:
- Introduce new `check*` functions which unify the logic (the error
handling unfortunately still needs some duplication for now)
- Make both `force*` and `eval*` use the `check*` function for the
actual type checking
- Inline and dismantle the `eval*` functions for being of little use and
little used. This makes the `ExprOp*::eval` implementations for binary
logic operators more verbose, but IMO that's a good thing: The
implementation now needs to be a lot more explicit about the
short-circuiting semantics, something which was previously hidden behind
the short-circuiting semantics of the C++ language, in a way that could
easily be overlooked and lead to confusion, which is something that
happened to me twice in a year.
- Changes `forceAttrs` and `forceList` to include the context in case
`forceValue` fails (compared to only when the type check fails). This
was done for code consistency, because I could not find any reason why
list and attrs had different semantics here than int, float and bool. So
far the visible change is minimal (see the diff on the err.exp), however
this needs vetting for potential performance regressions.
Change-Id: I33e5c706d46850c9e1126293ee01dab85ba07587