eval

Documentation

Overview

Package eval provides an expression evaluator.

Index

• func Format(e Expr) string
• type Env
• type Expr
  • func Parse(input string) (_ Expr, err error)
• type Var
  • func (v Var) Check(vars map[Var]bool) error
  • func (v Var) Eval(env Env) float64

Functions

func Format

func Format(e Expr) string

Format formats an expression as a string. It does not attempt to remove unnecessary parens.

Types

type Env

type Env map[Var]float64

type Expr

type Expr interface {
	// Eval returns the value of this Expr in the environment env.
	Eval(env Env) float64
	// Check reports errors in this Expr and adds its Vars to the set.
	Check(vars map[Var]bool) error
}

An Expr is an arithmetic expression.

func Parse

func Parse(input string) (_ Expr, err error)

type Var

type Var string

A Var identifies a variable, e.g., x.

func (Var) Check

func (v Var) Check(vars map[Var]bool) error

func (Var) Eval

func (v Var) Eval(env Env) float64