cds-lua-fp

cds.fp: map, filter, reduce, find, find_map, flat_map, filter_map, any,
all, set, unique, keys and each over lists, the function argument last.
cds.result: bind, map, context and traverse over Lua's own error
convention, a value or nil and an error. cds.module: the fallback a
module returns through so a name it does not have fails at the call, in
words. cds.needs: a check a program runs at startup for the functions it
declares. Pure Lua 5.1 and up, with language-server annotations throughout.