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» ConstList

…is a experimental compile-time functional-style list library written in C++.

The MIT licensed implementation may be found on Github or cgit.

It was written as a experiment in how far one could take the optional compile-time executability offered by constexpr specifically and the C++ template metaprogramming facilities in general. While basic Cons structures and appropriate accessor functions turned out to be quite straight forward to implement, the current problem is the absence of workable arbitrary value comparison in a templated context if one doesn’t want to be limited to values that can be used as template parameters such as integers. This means that it is currently impossible to e.g. filter a list using foldr.

Note that these restrictions were overcome in my second attempt at this problem which follows the concept of viewing types as values and templates as functions.

Current features

• Cons class template for representing constant list structures at compile time
• make method template for easily constructing Cons structures
• list constructors such as make and concatenate
• basic list accessors such as size, head, tail, nth and take
• higher order list operators such as foldr, foldl and map
• higher order list queries such as any, all, none and count
• special purpose methods such as reverse
• test cases for all of the above
• MIT license

Usage example

const int sum{
    ConstList::foldr(
        ConstList::make(1, 2, 3, 4, 5),
        [](const int& x, const int& y) {
            return x + y;
        },
        0
    )
}; // => 15