purescript-0.15.15: src/Language/PureScript/Docs/Prim.hs
-- | This module provides documentation for the builtin Prim modules.
module Language.PureScript.Docs.Prim
( primDocsModule
, primRowDocsModule
, primTypeErrorDocsModule
, primModules
) where
import Prelude hiding (fail)
import Data.Functor (($>))
import Data.Text (Text)
import Data.Text qualified as T
import Data.Map qualified as Map
import Language.PureScript.Docs.Types (Declaration(..), DeclarationInfo(..), Module(..), Type', convertFundepsToStrings)
import Language.PureScript.Constants.Prim qualified as P
import Language.PureScript.Crash qualified as P
import Language.PureScript.Environment qualified as P
import Language.PureScript.Names qualified as P
primModules :: [Module]
primModules =
[ primDocsModule
, primBooleanDocsModule
, primCoerceDocsModule
, primOrderingDocsModule
, primRowDocsModule
, primRowListDocsModule
, primSymbolDocsModule
, primIntDocsModule
, primTypeErrorDocsModule
]
primDocsModule :: Module
primDocsModule = Module
{ modName = P.moduleNameFromString "Prim"
, modComments = Just $ T.unlines
[ "The `Prim` module is embedded in the PureScript compiler in order to provide compiler support for certain types — for example, value literals, or syntax sugar. It is implicitly imported unqualified in every module except those that list it as a qualified import."
, ""
, "`Prim` does not include additional built-in types and kinds that are defined deeper in the compiler such as Type wildcards (e.g. `f :: _ -> Int`) and Quantified Types. Rather, these are documented in [the PureScript language reference](https://github.com/purescript/documentation/blob/master/language/Types.md)."
]
, modDeclarations =
[ function
, array
, record
, number
, int
, string
, char
, boolean
, partial
, kindType
, kindConstraint
, kindSymbol
, kindRow
]
, modReExports = []
}
primBooleanDocsModule :: Module
primBooleanDocsModule = Module
{ modName = P.moduleNameFromString "Prim.Boolean"
, modComments = Just "The Prim.Boolean module is embedded in the PureScript compiler. Unlike `Prim`, it is not imported implicitly. It contains a type level `Boolean` data structure."
, modDeclarations =
[ booleanTrue
, booleanFalse
]
, modReExports = []
}
primCoerceDocsModule :: Module
primCoerceDocsModule = Module
{ modName = P.moduleNameFromString "Prim.Coerce"
, modComments = Just "The Prim.Coerce module is embedded in the PureScript compiler. Unlike `Prim`, it is not imported implicitly. It contains an automatically solved type class for coercing types that have provably-identical runtime representations with [purescript-safe-coerce](https://pursuit.purescript.org/packages/purescript-safe-coerce)."
, modDeclarations =
[ coercible
]
, modReExports = []
}
primOrderingDocsModule :: Module
primOrderingDocsModule = Module
{ modName = P.moduleNameFromString "Prim.Ordering"
, modComments = Just "The Prim.Ordering module is embedded in the PureScript compiler. Unlike `Prim`, it is not imported implicitly. It contains a type level `Ordering` data structure."
, modDeclarations =
[ kindOrdering
, orderingLT
, orderingEQ
, orderingGT
]
, modReExports = []
}
primRowDocsModule :: Module
primRowDocsModule = Module
{ modName = P.moduleNameFromString "Prim.Row"
, modComments = Just "The Prim.Row module is embedded in the PureScript compiler. Unlike `Prim`, it is not imported implicitly. It contains automatically solved type classes for working with row types."
, modDeclarations =
[ union
, nub
, lacks
, rowCons
]
, modReExports = []
}
primRowListDocsModule :: Module
primRowListDocsModule = Module
{ modName = P.moduleNameFromString "Prim.RowList"
, modComments = Just "The Prim.RowList module is embedded in the PureScript compiler. Unlike `Prim`, it is not imported implicitly. It contains a type level list (`RowList`) that represents an ordered view of a row of types."
, modDeclarations =
[ kindRowList
, rowListCons
, rowListNil
, rowToList
]
, modReExports = []
}
primSymbolDocsModule :: Module
primSymbolDocsModule = Module
{ modName = P.moduleNameFromString "Prim.Symbol"
, modComments = Just "The Prim.Symbol module is embedded in the PureScript compiler. Unlike `Prim`, it is not imported implicitly. It contains automatically solved type classes for working with `Symbols`."
, modDeclarations =
[ symbolAppend
, symbolCompare
, symbolCons
]
, modReExports = []
}
primIntDocsModule :: Module
primIntDocsModule = Module
{ modName = P.moduleNameFromString "Prim.Int"
, modComments = Just "The Prim.Int module is embedded in the PureScript compiler. Unlike `Prim`, it is not imported implicitly. It contains automatically solved type classes for working with type-level intural numbers."
, modDeclarations =
[ intAdd
, intCompare
, intMul
, intToString
]
, modReExports = []
}
primTypeErrorDocsModule :: Module
primTypeErrorDocsModule = Module
{ modName = P.moduleNameFromString "Prim.TypeError"
, modComments = Just "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."
, modDeclarations =
[ warn
, fail
, kindDoc
, textDoc
, quoteDoc
, quoteLabelDoc
, besideDoc
, aboveDoc
]
, modReExports = []
}
unsafeLookup
:: forall v (a :: P.ProperNameType)
. Map.Map (P.Qualified (P.ProperName a)) v
-> String
-> P.Qualified (P.ProperName a)
-> v
unsafeLookup m errorMsg name = go name
where
go = fromJust' . flip Map.lookup m
fromJust' (Just x) = x
fromJust' _ = P.internalError $ errorMsg ++ show (P.runProperName $ P.disqualify name)
lookupPrimTypeKind
:: P.Qualified (P.ProperName 'P.TypeName)
-> Type'
lookupPrimTypeKind = ($> ()) . fst . unsafeLookup
( P.primTypes <>
P.primBooleanTypes <>
P.primOrderingTypes <>
P.primRowTypes <>
P.primRowListTypes <>
P.primTypeErrorTypes
) "Docs.Prim: No such Prim type: "
primType :: P.Qualified (P.ProperName 'P.TypeName) -> Text -> Declaration
primType tn comments = Declaration
{ declTitle = P.runProperName $ P.disqualify tn
, declComments = Just comments
, declSourceSpan = Nothing
, declChildren = []
, declInfo = ExternDataDeclaration (lookupPrimTypeKind tn) []
, declKind = Nothing
}
-- | Lookup the TypeClassData of a Prim class. This function is specifically
-- not exported because it is partial.
lookupPrimClass :: P.Qualified (P.ProperName 'P.ClassName) -> P.TypeClassData
lookupPrimClass = unsafeLookup
( P.primClasses <>
P.primCoerceClasses <>
P.primRowClasses <>
P.primRowListClasses <>
P.primSymbolClasses <>
P.primIntClasses <>
P.primTypeErrorClasses
) "Docs.Prim: No such Prim class: "
primClass :: P.Qualified (P.ProperName 'P.ClassName) -> Text -> Declaration
primClass cn comments = Declaration
{ declTitle = P.runProperName $ P.disqualify cn
, declComments = Just comments
, declSourceSpan = Nothing
, declChildren = []
, declInfo =
let
tcd = lookupPrimClass cn
args = fmap (fmap ($> ())) <$> P.typeClassArguments tcd
superclasses = ($> ()) <$> P.typeClassSuperclasses tcd
fundeps = convertFundepsToStrings args (P.typeClassDependencies tcd)
in
TypeClassDeclaration args superclasses fundeps
, declKind = Nothing
}
kindType :: Declaration
kindType = primType P.Type $ T.unlines
[ "`Type` is the kind of all proper types: those that classify value-level terms."
, "For example the type `Boolean` has kind `Type`; denoted by `Boolean :: Type`."
]
kindConstraint :: Declaration
kindConstraint = primType P.Constraint $ T.unlines
[ "`Constraint` is the kind of type class constraints."
, "For example, a type class declaration like this:"
, ""
, " class Semigroup a where"
, " append :: a -> a -> a"
, ""
, "has the kind signature:"
, ""
, " class Semigroup :: Type -> Constraint"
]
kindSymbol :: Declaration
kindSymbol = primType P.Symbol $ T.unlines
[ "`Symbol` is the kind of type-level strings."
, ""
, "Construct types of this kind using the same literal syntax as documented"
, "for strings."
, ""
, " type Hello :: Symbol"
, " type Hello = \"Hello, world\""
, ""
]
kindRow :: Declaration
kindRow = primType P.Row $ T.unlines
[ "`Row` is the kind constructor of label-indexed types which map type-level strings to other types."
, "The most common use of `Row` is `Row Type`, a row mapping labels to basic (of kind `Type`) types:"
, ""
, " type ExampleRow :: Row Type"
, " type ExampleRow = ( name :: String, values :: Array Int )"
, ""
, "This is the kind of `Row` expected by the `Record` type constructor."
, "More advanced row kinds like `Row (Type -> Type)` are used much less frequently."
]
function :: Declaration
function = primType P.Function $ T.unlines
[ "A function, which takes values of the type specified by the first type"
, "parameter, and returns values of the type specified by the second."
, "In the JavaScript backend, this is a standard JavaScript Function."
, ""
, "The type constructor `(->)` is syntactic sugar for this type constructor."
, "It is recommended to use `(->)` rather than `Function`, where possible."
, ""
, "That is, prefer this:"
, ""
, " f :: Number -> Number"
, ""
, "to either of these:"
, ""
, " f :: Function Number Number"
, " f :: (->) Number Number"
]
array :: Declaration
array = primType P.Array $ T.unlines
[ "An Array: a data structure supporting efficient random access. In"
, "the JavaScript backend, values of this type are represented as JavaScript"
, "Arrays at runtime."
, ""
, "Construct values using literals:"
, ""
, " x = [1,2,3,4,5] :: Array Int"
]
record :: Declaration
record = primType P.Record $ T.unlines
[ "The type of records whose fields are known at compile time. In the"
, "JavaScript backend, values of this type are represented as JavaScript"
, "Objects at runtime."
, ""
, "The type signature here means that the `Record` type constructor takes"
, "a row of concrete types. For example:"
, ""
, " type Person = Record (name :: String, age :: Number)"
, ""
, "The syntactic sugar with curly braces `{ }` is generally preferred, though:"
, ""
, " type Person = { name :: String, age :: Number }"
, ""
, "The row associates a type to each label which appears in the record."
, ""
, "_Technical note_: PureScript allows duplicate labels in rows, and the"
, "meaning of `Record r` is based on the _first_ occurrence of each label in"
, "the row `r`."
]
number :: Declaration
number = primType P.Number $ T.unlines
[ "A double precision floating point number (IEEE 754)."
, ""
, "Construct values of this type with literals."
, "Negative literals must be wrapped in parentheses if the negation sign could be mistaken"
, "for an infix operator:"
, ""
, " x = 35.23 :: Number"
, " y = -1.224e6 :: Number"
, " z = exp (-1.0) :: Number"
]
int :: Declaration
int = primType P.Int $ T.unlines
[ "A 32-bit signed integer. See the `purescript-integers` package for details"
, "of how this is accomplished when compiling to JavaScript."
, ""
, "Construct values of this type with literals. Hexadecimal syntax is supported."
, "Negative literals must be wrapped in parentheses if the negation sign could be mistaken"
, "for an infix operator:"
, ""
, " x = -23 :: Int"
, " y = 0x17 :: Int"
, " z = complement (-24) :: Int"
, ""
, "Integers used as types are considered to have kind `Int`."
, "Unlike value-level `Int`s, which must be representable as a 32-bit signed integer,"
, "type-level `Int`s are unbounded. Hexadecimal support is also supported at the type level."
, ""
, " type One :: Int"
, " type One = 1"
, " "
, " type Beyond32BitSignedInt :: Int"
, " type Beyond32BitSignedInt = 2147483648"
, " "
, " type HexInt :: Int"
, " type HexInt = 0x17"
, ""
, "Negative integer literals at the type level must be"
, "wrapped in parentheses if the negation sign could be mistaken for an infix operator."
, ""
, " type NegativeOne = -1"
, " foo :: Proxy (-1) -> ..."
]
string :: Declaration
string = primType P.String $ T.unlines
[ "A String. As in JavaScript, String values represent sequences of UTF-16"
, "code units, which are not required to form a valid encoding of Unicode"
, "text (for example, lone surrogates are permitted)."
, ""
, "Construct values of this type with literals, using double quotes `\"`:"
, ""
, " x = \"hello, world\" :: String"
, ""
, "Multi-line string literals are also supported with triple quotes (`\"\"\"`):"
, ""
, " x = \"\"\"multi"
, " line\"\"\""
, ""
, "At the type level, string literals represent types with kind `Symbol`."
, "These types will have kind `String` in a future release:"
, ""
, " type Hello :: Symbol"
, " type Hello = \"Hello, world\""
]
char :: Declaration
char = primType P.Char $ T.unlines
[ "A single character (UTF-16 code unit). The JavaScript representation is a"
, "normal `String`, which is guaranteed to contain one code unit. This means"
, "that astral plane characters (i.e. those with code point values greater"
, "than `0xFFFF`) cannot be represented as `Char` values."
, ""
, "Construct values of this type with literals, using single quotes `'`:"
, ""
, " x = 'a' :: Char"
]
boolean :: Declaration
boolean = primType P.Boolean $ T.unlines
[ "A JavaScript Boolean value."
, ""
, "Construct values of this type with the literals `true` and `false`."
, ""
, "The `True` and `False` types defined in `Prim.Boolean` have this type as their kind."
]
partial :: Declaration
partial = primClass P.Partial $ T.unlines
[ "The Partial type class is used to indicate that a function is *partial,*"
, "that is, it is not defined for all inputs. In practice, attempting to use"
, "a partial function with a bad input will usually cause an error to be"
, "thrown, although it is not safe to assume that this will happen in all"
, "cases. For more information, see"
, "[purescript-partial](https://pursuit.purescript.org/packages/purescript-partial/)."
]
booleanTrue :: Declaration
booleanTrue = primType P.True $ T.unlines
[ "The 'True' boolean type."
]
booleanFalse :: Declaration
booleanFalse = primType P.False $ T.unlines
[ "The 'False' boolean type."
]
coercible :: Declaration
coercible = primClass P.Coercible $ T.unlines
[ "Coercible is a two-parameter type class that has instances for types `a`"
, "and `b` if the compiler can infer that they have the same representation."
, "Coercible constraints are solved according to the following rules:"
, ""
, "* _reflexivity_, any type has the same representation as itself:"
, "`Coercible a a` holds."
, ""
, "* _symmetry_, if a type `a` can be coerced to some other type `b`, then `b`"
, "can also be coerced back to `a`: `Coercible a b` implies `Coercible b a`."
, ""
, "* _transitivity_, if a type `a` can be coerced to some other type `b` which"
, "can be coerced to some other type `c`, then `a` can also be coerced to `c`:"
, "`Coercible a b` and `Coercible b c` imply `Coercible a c`."
, ""
, "* Newtypes can be freely wrapped and unwrapped when their constructor is"
, "in scope:"
, ""
, " newtype Age = Age Int"
, ""
, "`Coercible Int Age` and `Coercible Age Int` hold since `Age` has the same"
, "runtime representation than `Int`."
, ""
, "Newtype constructors have to be in scope to preserve abstraction. It's"
, "common to declare a newtype to encode some invariants (non emptiness of"
, "arrays with `Data.Array.NonEmpty.NonEmptyArray` for example), hide its"
, "constructor and export smart constructors instead. Without this restriction,"
, "the guarantees provided by such newtypes would be void."
, ""
, "* If none of the above are applicable, two types of kind `Type` may be"
, "coercible, but only if their heads are the same. For example,"
, "`Coercible (Maybe a) (Either a b)` does not hold because `Maybe` and"
, "`Either` are different. Those types don't share a common runtime"
, "representation so coercing between them would be unsafe. In addition their"
, "arguments may need to be identical or coercible, depending on the _roles_"
, "of the head's type parameters. Roles are documented in [the PureScript"
, "language reference](https://github.com/purescript/documentation/blob/master/language/Roles.md)."
, ""
, "Coercible being polykinded, we can also coerce more than types of kind `Type`:"
, ""
, "* Rows are coercible when they have the same labels, when the corresponding"
, "pairs of types are coercible and when their tails are coercible:"
, "`Coercible ( label :: a | r ) ( label :: b | s )` holds when"
, "`Coercible a b` and `Coercible r s` do. Closed rows cannot be coerced to"
, "open rows."
, ""
, "* Higher kinded types are coercible if they are coercible when fully"
, "saturated: `Coercible (f :: _ -> Type) (g :: _ -> Type)` holds when"
, "`Coercible (f a) (g a)` does."
, ""
, "This rule may seem puzzling since there is no term of type `_ -> Type` to"
, "apply `coerce` to, but it is necessary when coercing types with higher"
, "kinded parameters."
]
kindOrdering :: Declaration
kindOrdering = primType P.TypeOrdering $ T.unlines
[ "The `Ordering` kind represents the three possibilities of comparing two"
, "types of the same kind: `LT` (less than), `EQ` (equal to), and"
, "`GT` (greater than)."
]
orderingLT :: Declaration
orderingLT = primType P.LT $ T.unlines
[ "The 'less than' ordering type."
]
orderingEQ :: Declaration
orderingEQ = primType P.EQ $ T.unlines
[ "The 'equal to' ordering type."
]
orderingGT :: Declaration
orderingGT = primType P.GT $ T.unlines
[ "The 'greater than' ordering type."
]
union :: Declaration
union = primClass P.RowUnion $ T.unlines
[ "The Union type class is used to compute the union of two rows of types"
, "(left-biased, including duplicates)."
, ""
, "The third type argument represents the union of the first two."
]
nub :: Declaration
nub = primClass P.RowNub $ T.unlines
[ "The Nub type class is used to remove duplicate labels from rows."
]
lacks :: Declaration
lacks = primClass P.RowLacks $ T.unlines
[ "The Lacks type class asserts that a label does not occur in a given row."
]
rowCons :: Declaration
rowCons = primClass P.RowCons $ T.unlines
[ "The Cons type class is a 4-way relation which asserts that one row of"
, "types can be obtained from another by inserting a new label/type pair on"
, "the left."
]
kindRowList :: Declaration
kindRowList = primType P.RowList $ T.unlines
[ "A type level list representation of a row of types."
]
rowListCons :: Declaration
rowListCons = primType P.RowListCons $ T.unlines
[ "Constructs a new `RowList` from a label, a type, and an existing tail"
, "`RowList`. E.g: `Cons \"x\" Int (Cons \"y\" Int Nil)`."
]
rowListNil :: Declaration
rowListNil = primType P.RowListNil $ T.unlines
[ "The empty `RowList`."
]
rowToList :: Declaration
rowToList = primClass P.RowToList $ T.unlines
[ "Compiler solved type class for generating a `RowList` from a closed row"
, "of types. Entries are sorted by label and duplicates are preserved in"
, "the order they appeared in the row."
]
symbolAppend :: Declaration
symbolAppend = primClass P.SymbolAppend $ T.unlines
[ "Compiler solved type class for appending `Symbol`s together."
]
symbolCompare :: Declaration
symbolCompare = primClass P.SymbolCompare $ T.unlines
[ "Compiler solved type class for comparing two `Symbol`s."
, "Produces an `Ordering`."
]
symbolCons :: Declaration
symbolCons = primClass P.SymbolCons $ T.unlines
[ "Compiler solved type class for either splitting up a symbol into its"
, "head and tail or for combining a head and tail into a new symbol."
, "Requires the head to be a single character and the combined string"
, "cannot be empty."
]
intAdd :: Declaration
intAdd = primClass P.IntAdd $ T.unlines
[ "Compiler solved type class for adding type-level `Int`s."
]
intCompare :: Declaration
intCompare = primClass P.IntCompare $ T.unlines
[ "Compiler solved type class for comparing two type-level `Int`s."
, "Produces an `Ordering`."
]
intMul :: Declaration
intMul = primClass P.IntMul $ T.unlines
[ "Compiler solved type class for multiplying type-level `Int`s."
]
intToString :: Declaration
intToString = primClass P.IntToString $ T.unlines
[ "Compiler solved type class for converting a type-level `Int` into a type-level `String` (i.e. `Symbol`)."
]
fail :: Declaration
fail = primClass P.Fail $ T.unlines
[ "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](https://github.com/purescript/documentation/blob/master/guides/Custom-Type-Errors.md)."
]
warn :: Declaration
warn = primClass P.Warn $ T.unlines
[ "The Warn type class allows a custom compiler warning to be displayed."
, ""
, "For more information, see"
, "[the Custom Type Errors guide](https://github.com/purescript/documentation/blob/master/guides/Custom-Type-Errors.md)."
]
kindDoc :: Declaration
kindDoc = primType P.Doc $ T.unlines
[ "`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`."
]
textDoc :: Declaration
textDoc = primType P.Text $ T.unlines
[ "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](https://github.com/purescript/documentation/blob/master/guides/Custom-Type-Errors.md)."
]
quoteDoc :: Declaration
quoteDoc = primType P.Quote $ T.unlines
[ "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](https://github.com/purescript/documentation/blob/master/guides/Custom-Type-Errors.md)."
]
quoteLabelDoc :: Declaration
quoteLabelDoc = primType P.QuoteLabel $ T.unlines
[ "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](https://github.com/purescript/documentation/blob/master/guides/Custom-Type-Errors.md)."
]
besideDoc :: Declaration
besideDoc = primType P.Beside $ T.unlines
[ "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](https://github.com/purescript/documentation/blob/master/guides/Custom-Type-Errors.md)."
]
aboveDoc :: Declaration
aboveDoc = primType P.Above $ T.unlines
[ "The Above type constructor combines two Docs vertically"
, "in a custom type error."
, ""
, "For more information, see"
, "[the Custom Type Errors guide](https://github.com/purescript/documentation/blob/master/guides/Custom-Type-Errors.md)."
]