Cannot specify nil as the desired fetch value from Monadic:Nothing

[pzol]

Cannot specify nil as the desired fetch value from Monadic:Nothing

[paploo]

On second thought, I'm not sure why you'd ever want fetch to return Nothing, since the point of fetch is to unwrap the value in the monad and return to Ruby land. Why not just implement as:

def fetch(default=nil)
  default
end

[SkyWriter]

@paploo have you ever found a sound way to get around this?

[sdbondi]

Hi,

Made a PR for this.
Basically if you don't give an explicit argument it will return Nothing as before.
If you explicitly say "give me nil (or whatever value)" it will for Nothing.

Maybe(nil)._ == Nothing
Maybe(nil)._(nil) == nil
Maybe(nil)._('') == ''

EDIT: Just read @paploo's implementation, had the same idea :)

EDIT2: @paploo the only problem I found with making fetch return the default is the Elvis Operator.

# if:
nil._? == nil
# then we cant do:
nil._?.a.b # will throw undefined method `a' for nil:NilClass
# so the result should stay as it currently is
nil._?.a.b == Nothing

There may be other reasons, but I'm not aware of them