TypedEnv

fromEnv :: forall proxy r e. ReadEnv e r => proxy e -> Object String -> Either EnvError (Record r)

Gets a record of environment variables from a Node environment.

data Variable (name :: Symbol) (ty :: Type)

Specifies the name and type of an environment variable.

Instances

• (IsSymbol name, IsSymbol varName, ListToRow rlt rt, ReadEnvFields elt rlt rt, Lacks name rt, Cons name ty rt r, ReadValue ty) => ReadEnvFields (Cons name (Variable varName ty) elt) (Cons name ty rlt) r

type VariableFlipped ty name = Variable name ty

An alias for Variable with the parameters reversed

Operator alias for TypedEnv.VariableFlipped (right-associative / precedence 5)

An alias for VariableFlipped

data EnvError

An error that can occur while reading an environment variable

Constructors

• EnvLookupError String
• EnvParseError String

Instances

• Eq EnvError
• Generic EnvError _
• Show EnvError

envErrorMessage :: EnvError -> String

Gets the error message for a given EnvError value.

type Resolved (name :: Symbol) ty = ty

Useful for a type alias representing a resolved environment

class ParseValue ty  where

Parses a String value to the specified type.

Members

• parseValue :: String -> Maybe ty

Instances

• ParseValue Boolean
• ParseValue Char
• ParseValue Int
• ParseValue Number
• ParseValue String

class ReadValue ty  where

Retrieves and parses an environment variable value.

Members

• readValue :: String -> Object String -> Either EnvError ty

Instances

• (ParseValue a) => ReadValue (Maybe a)
• (ParseValue a) => ReadValue a

class ReadEnv (e :: Row Type) (r :: Row Type)  where

Transforms a row of environment variable specifications to a record.

Members

• readEnv :: forall proxy. proxy e -> Object String -> Either EnvError (Record r)

Instances

• (RowToList e el, RowToList r rl, ReadEnvFields el rl r, ListToRow rl r, ListToRow el l) => ReadEnv e r

class ReadEnvFields (el :: RowList) (rl :: RowList) (r :: Row Type) | el -> rl where

Transforms a list of environment variable specifications to a record.

Members

• readEnvFields :: forall proxy. proxy el -> proxy rl -> Object String -> Either EnvError (Record r)

Instances

• (IsSymbol name, IsSymbol varName, ListToRow rlt rt, ReadEnvFields elt rlt rt, Lacks name rt, Cons name ty rt r, ReadValue ty) => ReadEnvFields (Cons name (Variable varName ty) elt) (Cons name ty rlt) r
• (TypeEquals (Record ()) (Record row)) => ReadEnvFields Nil Nil row