​​Module system examples

​​futures-rs

• ​​Public surface

• ​​Several submodules, no nesting within them

• ​​Several type definitions and re-exports

• ​​Internal surface

• ​​many nested modules for file organization and namespacing

• ​​generally each provides one or two definitions that are re-exported by the parent

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​​regex

• ​​Public surface

• ​​Almost entirely flat, except bytes submodule (which is like an entire alternative API surface)

• ​​Internal surface

• ​​flat

• ​​seemingly mostly for file organization

• ​​some use of privacy

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​​rayon

• ​​Public surface

• ​​Quite a few submodules, with further nesting within them

• ​​The nested submodules are very small — most define Iter and IntoIter for particular types

• ​​These definitions would not need to be exposed if we had impl Trait in trait impls

• ​​Could also just re-organize these into a single submodule

• ​​Several functions and types defined at top level

• ​​Internal surface

• ​​Many public submodules are just files

• ​​These are mixed with files that do not define public submodules, making it difficult to discern the module structure

• ​​This seems to come down to the impl Trait issue above

• ​​test.rs at root level

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​​log

• ​​Public surface

• ​​No submodules

• ​​Internal surface

• ​​Just one file

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​​openssl

• ​​Public surface

• ​​Many submodules at root, no nesting

• ​​Only one function at top level

• ​​Internal surface

• ​​Mostly flat list of files

• ​​Most correspond to public submodules, but some do not

​​

​​flate2

• ​​Public surface

• ​​A few submodules, each of which contains a bunch of types

• ​​Several definitions at top level

• ​​Internal surface

• ​​Directory/file structure doesn’t match public API surface at all