Traits for transforming bits of IR.
pub use self::shift::Shift; |
| shift | Shifting of debruijn indices
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| Subst | Substitution used during folding
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| Fold | Applies the given Folder to a value, producing a folded result
of type Self::Result. The result type is typically the same as
the source type, but in some cases we convert from borrowed
to owned as well (e.g., the folder for &T will fold to a fresh
T; well, actually T::Result).
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| Folder | A "folder" is a transformer that can be used to make a copy of
some term -- that is, some bit of IR, such as a Goal -- with
certain changes applied. The idea is that it contains methods that
let you swap types/lifetimes for new types/lifetimes; meanwhile,
each bit of IR implements the Fold trait which, given a
Folder, will reconstruct itself, invoking the folder's methods
to transform each of the types/lifetimes embedded within.
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| SuperFold | For types where "fold" invokes a callback on the Folder, the
SuperFold trait captures the recursive behavior that folds all
the contents of the type.
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