Add a class to create Foreign types #42
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Allows specifying the exact format of JavaScript values for FFI code:
data A = A (Maybe String) (Maybe String)
instance aAsForeign :: AsForeign A where
write (A x y) = writeObject [ "x" .= Null x
, "y" .= Null y
]
foreign import data B :: *
foreign import convertImpl :: Foreign -> B
convert :: A -> B
convert = convertImpl <<< asForeign
Fixes purescript#31
| readArray value | isArray value = pure $ unsafeFromForeign value | ||
| readArray value = Left (TypeMismatch "array" (tagOf value)) | ||
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| newtype Prop = Prop { key :: String, value :: Foreign } |
Member
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It might be better to use a non-record type here, as data constructors with multiple fields perform better than records in most JS VMs (cheaper to construct due to the "hidden class" optimisation). Maybe just a type Prop = Tuple String Foreign even?
edit: as pointed out on IRC, Prop is destined for the FFI, so a record works better here.
Contributor
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Can this and/or writeObject get comments (ideally with an example) please?
Member
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Ping @paf31. Any comments here or shall I merge this? |
| instance intAsForeign :: AsForeign Int where | ||
| write = toForeign | ||
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| instance arrayAsForeign :: (AsForeign a) => AsForeign (Array a) where |
Contributor
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Looks great 👍 |
Member
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Sorry about the delay in merging @puffnfresh, it's out now as 1.1.0. |
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Allows specifying the exact format of JavaScript values for FFI code:
Fixes #31