Prim.TypeError
The Prim.TypeError module is embedded in the PureScript compiler. Unlike Prim
, it is not imported implicitly. It contains type classes that provide custom type error and warning functionality.
#Warn
class Warn (message :: Doc)
The Warn type class allows a custom compiler warning to be displayed.
For more information, see the Custom Type Errors guide.
#Fail
class Fail (message :: Doc)
The Fail type class is part of the custom type errors feature. To provide a custom type error when someone tries to use a particular instance, write that instance out with a Fail constraint.
For more information, see the Custom Type Errors guide.
#Doc
data Doc :: Type
Doc
is the kind of type-level documents.
This kind is used with the Fail
and Warn
type classes.
Build up a Doc
with Text
, Quote
, QuoteLabel
, Beside
, and Above
.
#Text
data Text :: Symbol -> Doc
The Text type constructor makes a Doc from a Symbol to be used in a custom type error.
For more information, see the Custom Type Errors guide.
#Quote
data Quote :: Type -> Doc
The Quote type constructor renders any concrete type as a Doc to be used in a custom type error.
For more information, see the Custom Type Errors guide.
#QuoteLabel
data QuoteLabel :: Symbol -> Doc
The QuoteLabel
type constructor will produce a Doc
when given a Symbol
. When the resulting Doc
is rendered
for a Warn
or Fail
constraint, a syntactically valid label will be produced, escaping with quotes as needed.
For more information, see the Custom Type Errors guide.
#Beside
data Beside :: Doc -> Doc -> Doc
The Beside type constructor combines two Docs horizontally to be used in a custom type error.
For more information, see the Custom Type Errors guide.
#Above
data Above :: Doc -> Doc -> Doc
The Above type constructor combines two Docs vertically in a custom type error.
For more information, see the Custom Type Errors guide.