Language.Scheme.Types

Documentation

data Env

A Scheme environment containing variable bindings of form (namespaceName, variableName), variableValue

Constructors

Environment

Fields

parentEnv :: Maybe Env

bindings :: IORef [((String, String), IORef LispVal)]

nullEnv :: IO Env

An empty environment

macroNamespace :: [Char]

varNamespace :: [Char]

data LispError

Types of errors that may occur when evaluating Scheme code

Constructors

NumArgs Integer [LispVal]

Invalid number of function arguments

TypeMismatch String LispVal

Type error

Parser ParseError

Parsing error

BadSpecialForm String LispVal

Invalid special (built-in) form

NotFunction String String

UnboundVar String String

DivideByZero

Divide by Zero error

NotImplemented String

InternalError String

An internal error within husk; in theory user (Scheme) code should never allow one of these errors to be triggered.

Default String

Default error

Instances

Show LispError

Error LispError

showError :: LispError -> String

Create a textual description for a LispError

type ThrowsError = Either LispError

trapError :: (MonadError e m, Show e) => m String -> m String

extractValue :: ThrowsError a -> a

type IOThrowsError = ErrorT LispError IO

liftThrows :: ThrowsError a -> IOThrowsError a

runIOThrows :: IOThrowsError String -> IO String

data LispVal

Scheme data types

Constructors

Atom String

Symbol

List [LispVal]

List

DottedList [LispVal] LispVal

Pair

Vector (Array Int LispVal)

Vector

HashTable (Map LispVal LispVal)

Hash table. Technically this could be a derived data type instead of being built-in to the interpreter. And perhaps in the future it will be. But for now, a hash table is too important of a data type to not be included.

Map is technically the wrong structure to use for a hash table since it is based on a binary tree and hence operations tend to be O(log n) instead of O(1). However, according to http://www.opensubscriber.com/message/[e-mail]/10779624.html Map has good performance characteristics compared to the alternatives. So it stays for the moment...

Number Integer

Integer

Float Double

Floating point

Complex (Complex Double)

Complex number

Rational Rational

Rational number

String String

String

Char Char

Character

Bool Bool

Boolean

PrimitiveFunc ([LispVal] -> ThrowsError LispVal)

Func

Function

Fields

params :: [String]

vararg :: Maybe String

body :: [LispVal]

closure :: Env

IOFunc ([LispVal] -> IOThrowsError LispVal)

Port Handle

I/O port

Continuation

Continuation

Fields

closure :: Env

body :: [LispVal]

continuation :: LispVal

contFunctionArgs :: Maybe [LispVal]

continuationFunction :: Maybe (Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal)

Nil String

Internal use only; do not use this type directly.

Instances

Eq LispVal

Ord LispVal

Show LispVal

Allow conversion of lispval instances to strings

makeNullContinuation :: Env -> LispVal

makeCPS :: Env -> LispVal -> (Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal) -> LispVal

makeCPSWArgs :: Env -> LispVal -> (Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal) -> [LispVal] -> LispVal

eqv :: [LispVal] -> ThrowsError LispVal

Compare two LispVal instances

eqvList :: ([LispVal] -> ThrowsError LispVal) -> [LispVal] -> ThrowsError LispVal

eqVal :: LispVal -> LispVal -> Bool

showVal :: LispVal -> String

Create a textual description of a LispVal

unwordsList :: [LispVal] -> String