Language.Qux.Interpreter

Functions for executing a program and retrieving the return result.

This module assumes the program is well-formed. That is, it must be well-typed (see Language.Qux.TypeChecker).

Environment

type Execution = EitherT Value Evaluation

An environment that holds the global state (Reader Context) and the local state (Locals). It supports breaking out of execution (via 'EitherT Value').

type Evaluation = StateT Locals (Reader Context)

An environment that holds the global state (Reader Context) and the local state (Locals). Purely for evaluation of expressions---this environment does not support breaking out of execution.

runExecution :: (a -> Value) -> Execution a -> Evaluation Value

Contexts

data Context

Global context that holds function definitions. The function name, parameter names and statements are held.

type Locals = Map Id Value

Local context.

context :: Program -> Context

Returns a context for the given program.

Interpreter

Program execution

exec :: Program -> Id -> [Value] -> Value

exec program entry arguments executes entry (passing it arguments) in the context of program. This function wraps execFunction by building and evaluating the environment under the hood.

execStmt :: Stmt -> Execution ()

Executes the statement in a breaking environment.

Expression evaluation

evalExpr :: Expr -> Evaluation Value

Reduces the expression to a value (normal form).