This PR "monomorphizes" the structure `Std.PRange shape α`, replacing it
with nine distinct structures `Std.Rcc`, `Std.Rco`, `Std.Rci` etc., one
for each possible shape of a range's bounds. This change was necessary
because the shape polymorphism is detrimental to attempts of automation.
**BREAKING CHANGE:** While range/slice notation itself is unchanged,
this essentially breaks the entire remaining (polymorphic) range and
slice API except for the dot-notation(`toList`, `iter`, ...). It is not
possible to deprecate old declarations that were formulated in a
shape-polymorphic way that is not available anymore.
This PR fixes a panic in the delaborator for `Std.PRange`. It also
modifies the delaborators for both `Std.Range` and `Std.PRange` to not
use `let_expr`, which cleans up annotations and metadata, since
delaborators must follow the structures of expressions. It adds support
for `pp.notation` and `pp.explicit` options. It also adds tests for
these delaborators.
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Co-authored-by: Kim Morrison <kim@tqft.net>
Co-authored-by: Kyle Miller <kmill31415@gmail.com>
