Feldspar.DSL.Expression

This module defines the concept of expressions and expression transformers.

An expression is a type constructor of kind

 * -> * -> *

where the first argument denotes the "role" of the expression, and the second argument is the type of the value computed by the expression.

An expression transformer is a type constructor of kind

 (* -> * -> *) -> (* -> * -> *)

i.e. a expression parameterized by an expression.

Documentation

data Empty role a

Expression type with no constructors. Can be used to turn an expression transformer to an expression.

Instances

ExprShow Empty

Eval Empty

ExprEq Empty

Eq (Empty role a)

class ExprEq expr where

Equality for expressions. The difference between Eq and ExprEq is that ExprEq allows comparison of expressions with different role and value type. It is assumed that when the types differ, the expressions also differ. The reason for allowing comparison of different types is that this is convenient when the types are existentially quantified.

Methods

exprEq :: expr ra a -> expr rb b -> Bool

Instances

ExprEq Empty

ExprEq Val

ExprEq Feldspar

ExprEq expr => ExprEq (Lam expr)

ExprEq node => ExprEq (Connection edge node)

class Eval expr where

Evaluation of expressions

Methods

eval :: expr role a -> a

Instances

Eval Empty

Eval Val

Eval Feldspar

Eval expr => Eval (Lam expr)

Eval node => Eval (Connection edge node)

class ExprShow expr where

Methods

exprShow :: expr role a -> String

Instances

ExprShow Empty

ExprShow Val

ExprShow EdgeSize

ExprShow Feldspar

ExprShow expr => ExprShow (Lam expr)

(ExprShow edge, ExprShow node) => ExprShow (Connection edge node)

printExpr :: ExprShow expr => expr role a -> IO ()

exprCast :: forall expr ra a rb b. (Typeable ra, Typeable a, Typeable rb, Typeable b) => expr ra a -> Maybe (expr rb b)

Type-safe cast for expressions