Add Enumerable#find_value
#14893
Add Enumerable#find_value
#14893
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Co-authored-by: Sijawusz Pur Rahnama <sija@sija.pl>
| # [1, 2, 3, 4].find_value { |i| i > 8 } # => nil | ||
| # [1, 2, 3, 4].find_value(-1) { |i| i > 8 } # => -1 | ||
| # ``` | ||
| def find_value(if_none = nil, & : T ->) |
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I think it would be of some benefit to have the method strictly typed rather than leaving the compiler to infer everything. We had a discussion in the Discord server and concluded it would mean having an overload specifically for a nil/no-default case, but I think that would be better overall:
def find_value(if_none : U, & : T -> V) : V forall U, V
def find_value(& : T -> U) : U? forall UThere was a problem hiding this comment.
I'm a fan of explicit types, but this is still type inference. What benefit are you seeing here that I'm not seeing?
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I find that the explicitness of method signatures are more useful even if there is no real difference between them. It's also clear what the return type of the method is as both I and another Crystal user initially misinterpreted the return type as being the value of the enumerable type (i.e. T). When taking into account Enumerable#find which has an identical signature, it makes sense to be explicit here to reduce confusion.
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I agree that it's more explicit, but I don't know if I agree that it reduces confusion. To my eyes, it just looks like a jumble of type placeholders.
Does the doc comment provide insufficient disambiguation between it and find?
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I think type restrictions are always helpful as they document the expectations of input and ouput types. Even if it's a bit complicated to express.
IMO we should ideally always write down all type restrictions as part of the API documentation.
As a comment on the suggested format, different names T -> V and T -> U are confusing. They're doing the same thing, so both proc types should use the same name for their output type.
Fixes #14879