Safe Haskell	None
Language	Haskell2010

DataFrame.Schema

Description

The runtime schema surface for the dataframe ecosystem: the Schema tag, its element types, and builders to describe a frame's columns by name. Re-exported so callers never reach into DataFrame.Internal.Schema.

Synopsis

newtype Schema = Schema {
- elements :: Map Text SchemaType
}
data SchemaType where
- SType :: forall a. (Columnable a, Read a) => Proxy a -> SchemaType
schemaType :: (Columnable a, Read a) => SchemaType
makeSchema :: [(Text, SchemaType)] -> Schema
class RuntimeSchema (cols :: [(Symbol, Type)]) where
- runtimeSchema :: Schema

Documentation

newtype Schema Source #

Logical schema of a DataFrame: a mapping from column names to their element types (SchemaType).

Constructors

Schema
Fields elements :: Map Text SchemaType Mapping from column name to its `SchemaType`. Invariant: keys are unique column names. A missing key means the column is not present in the schema.

Instances

Instances details

Show Schema Source #
Instance details Defined in DataFrame.Internal.Schema Methods showsPrec :: Int -> Schema -> ShowS # show :: Schema -> String # showList :: [Schema] -> ShowS #
Eq Schema Source #
Instance details Defined in DataFrame.Internal.Schema Methods (==) :: Schema -> Schema -> Bool # (/=) :: Schema -> Schema -> Bool #

data SchemaType where Source #

A runtime tag for a column’s element type.

Constructors

SType :: forall a. (Columnable a, Read a) => Proxy a -> SchemaType

Constructor carrying a Proxy of the element type.

Instances

Instances details

Show SchemaType Source #	Show the underlying element type using `typeRep`. Examples Expand `>>>` `:set -XTypeApplications``>>>` `show (schemaType @Bool)`"Bool"
Instance details Defined in DataFrame.Internal.Schema Methods showsPrec :: Int -> SchemaType -> ShowS # show :: SchemaType -> String # showList :: [SchemaType] -> ShowS #
Eq SchemaType Source #	Two `SchemaType`s are equal iff their element types are the same. Examples Expand `>>>` `:set -XTypeApplications``>>>` `schemaType @Int == schemaType @Int`True `>>>` `schemaType @Int == schemaType @Integer`False
Instance details Defined in DataFrame.Internal.Schema Methods (==) :: SchemaType -> SchemaType -> Bool # (/=) :: SchemaType -> SchemaType -> Bool #

schemaType :: (Columnable a, Read a) => SchemaType Source #

Construct a SchemaType for the given a.

Examples

Expand

>>> :set -XTypeApplications
>>> schemaType @T.Text == schemaType @T.Text
True

>>> show (schemaType @Double)
"Double"

makeSchema :: [(Text, SchemaType)] -> Schema Source #

Construct a Schema from a list of (columnName, schemaType) pairs.

class RuntimeSchema (cols :: [(Symbol, Type)]) where Source #

The runtime Schema behind a type-level schema — names and element types — so a reader can project to a schema's columns and skip inference for them in one step.

Every column type must have a Read instance, which Columnable does not imply; that is what lets the names carry their types across to a reader.

Examples

Expand

>>> :set -XTypeApplications -XDataKinds
>>> elements (runtimeSchema @'[ '("n", Int)])
fromList [("n",Int)]

Methods

runtimeSchema :: Schema Source #

Instances

Instances details

RuntimeSchema ('[] :: [(Symbol, Type)]) Source #
Instance details Defined in DataFrame.Internal.Schema Methods runtimeSchema :: Schema Source #
(KnownSymbol name, Columnable a, Read a, RuntimeSchema rest) => RuntimeSchema ('(name, a) ': rest) Source #
Instance details Defined in DataFrame.Internal.Schema Methods runtimeSchema :: Schema Source #