Change the support code for directory creation so that it sets all
permission bits (ugo=rwx). The process's currently active umask will be
subtracted from these permissions, which leads to the result that (for a
standard umask of "022") directories are created with a mode of "0755".
So by default, directories created with `prim__createDir` are now also
group-executable and other-executable by default.
Previous behaviour was to create the directories readable for group and
other, but not executable (mode "744"), and thus inaccessible to anyone
except the owner.
Snoc add an element at the end of the vector. The main use case
for such a function is to get the expected type signature
Vect n a -> a -> Vect (S n) a instead of
Vect n a -> a -> Vect (n + 1) a which you get by using `++ [x]`
Snoc gets is name from `cons` by reversin each letter, indicating
tacking on the element at the end rather than the begining.
`append` would also be a suitable name.
This is a first attempt so I've probably got something wrong...
In theory, it ought to be possible to skip the tests for the previous
version. All we're interested in here is whether it builds successfully,
to check that we haven't broken any APIs and not noticed.
Local hints need to reduce (just like global hints do) so we expand
their definition to the lifted name before applying them.
We're identifying the global hints by knowing that the binder name is a
nested function name. This is a bit of hack, and it'd probably be better
to record that information in the binder instead, but that's a more
substantial change than I want to do right now.
This gives us the ability to define and use implementations locally, in
where clauses/local let bindings, as well as flag local definitions as
hints.
It's not yet quite equivalent to global hints, however, since it translated
the hint to a local let binding, which doesn't reduce, so if something
relies on the reduction behaviour of the hint, it won't work. This
refinement is coming later
