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Proposal: When a type mismatch is inside a record, print where. #4005
Description
Summary
If there is a type mismatch when trying to unify two records, e.g.
{ x: "foo" }
and
{ x: 3 }
the compiler will mention it couldn't match String with Int, but it won't say which label it's under.
Motivation
Less searching required to figure out where exactly the mismatch lies.
Proposal
On error messages which refer to anything inside a label, also mention the label (possibly its full path with nesting).
Examples
Real-world example with the type mismatch being somewhere down the hatches:
Could not match type
Maybe String
with type
String
while trying to match type
( getInputProps :: { _aria :: Object String
, autoComplete :: String
, id :: String
, onBlur :: EffectFn1 SyntheticEvent Unit
, onChange :: EffectFn1 SyntheticEvent Unit
, onKeyDown :: EffectFn1 SyntheticEvent Unit
, value :: String
}
, getItemProps :: { index :: Int
, item :: { value :: String
}
, key :: String
, style :: CSS
}
-> { _aria :: Object String
, id :: String
, role :: String
, style :: CSS
}
, getLabelProps :: { htmlFor :: String
, id :: String
, ref :: Ref (Nullable Node)
}
, getMenuProps :: { _aria :: Object String
, id :: String
, ref :: Ref (Nullable Node)
, role :: String
}
, getRootProps :: { _aria :: Object String
, ref :: Ref (Nullable Node)
, role :: String
}
, inputValue :: Maybe String
, selectedItem :: Maybe
{ value :: String
| t4
}
...
)
with type
( getInputProps :: Record t9
, getItemProps :: { index :: Int
, item :: { value :: String
}
, key :: String
, style :: CSS
}
-> Record t8
, getLabelProps :: Record t7
, getMenuProps :: Record t6
, getRootProps :: Record t5
, inputValue :: String
, selectedItem :: Maybe
{ value :: String
}
...
| t10
)
while solving type class constraint
Prim.Row.Union ( itemToString :: Nullable t1 -> String
, items :: Array t1
, renderChildren :: { getInputProps :: { _aria :: ...
, autoComplete :: String
, id :: String
, onBlur :: ...
, onChange :: ...
, onKeyDown :: ...
, value :: String
}
, getItemProps :: ... -> ...
, getLabelProps :: { htmlFor :: String
, id :: String
, ref :: ...
}
, getMenuProps :: { _aria :: ...
, id :: String
, ref :: ...
, role :: String
}
, getRootProps :: { _aria :: ...
, ref :: ...
, role :: String
}
, highlightedIndex :: Maybe Int
, inputValue :: Maybe String
, isOpen :: Boolean
, selectedItem :: Maybe t1
}
-> JSX
)
t2
( itemToString :: Nullable
{ value :: String
| t4
}
-> String
, onChange :: t3 -> t3
, renderChildren :: { getInputProps :: Record t9
, getItemProps :: ... -> ...
, getLabelProps :: Record t7
, getMenuProps :: Record t6
, getRootProps :: Record t5
, highlightedIndex :: Maybe Int
, inputValue :: String
, isOpen :: Boolean
, selectedItem :: Maybe ...
| t10
}
-> JSX
)
Activity