Add from-optional function #1327
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Jason94
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| @@ -23,6 +24,13 @@ | |||
| ;; Optional | |||
| ;; | |||
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| (declare from-optional (:a -> (Optional :a) -> :a)) | |||
| (define (from-optional def opt) | |||
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Personally I think maybe the variable should be 'default' for clarity
| (declare from-optional (:a -> (Optional :a) -> :a)) | ||
| (define (from-optional def opt) | ||
| "Get the value of OPT, or return DEF if OPT is None." | ||
| (match opt |
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This function has some overlap with 'unwrap-or-else', though I think that this may be a better syntax if you're not applying anything to the unwrapped element.
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It may be worth abstracting this so it could work for Result too, maybe make a function 'unwrap-or-default' that work for anything satisfying the 'unwrappable' class.
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Actually that abstraction already exists:
Line 321 in 19965eb
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Ah! Drat - I was afraid this was already covered by something I couldn't find. This PR probably adds no value then.
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Yeah, I'm going to go ahead and close. Thanks!
Adds a small utility function to
optional.lispto get the value from an option or a default value ifNone. Shamelessly stolen fromfromMaybefrom Haskell.