Add ability to define functions with dashes in name

.gitignore

@@ -1,2 +1,2 @@
-scpt
+/scpt
 .idea/

README.md

@@ -0,0 +1,81 @@
+# scpt
+
+scpt is an applescript-inspired scripting language written for fun and to see if I could.
+
+[![Go Reference](https://pkg.go.dev/badge/gitea.arsenm.dev/Arsen6331/scpt.svg)](https://pkg.go.dev/gitea.arsenm.dev/Arsen6331/scpt)
+
+---
+
+### Usage
+
+scpt is to be used as a library imported into Go. A basic interpreter with no extra functionality would look like this:
+
+```go
+package main
+
+import (
+	"gitea.arsenm.dev/Arsen6331/scpt"
+	"log"
+	"os"
+	"path/filepath"
+)
+
+func main() {
+	filename := os.Args[1]
+	file, err := os.Open(filepath.Clean(filename))
+	if err != nil {
+		log.Fatalln(err)
+	}
+	defer file.Close()
+	ast, err := scpt.Parse(file)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	err = ast.Execute()
+	if err != nil {
+		log.Fatalln(err)
+	}
+}
+```
+
+---
+
+### Basic Syntax
+
+The basic syntax of scpt can be learned from the test.scpt file.
+
+---
+
+### Default Functions
+
+scpt comes with the following default functions:
+
+- `str`: Convert value to string
+- `num`: Parse string to number (`float64`)
+- `bool`: Parse string to boolean
+- `break`: Break out of loop (Errors if not in loop)
+- `append`: Return an array with given items appended
+- `exit`: Exit with given exit code
+- `return`: Return value in function (Errors if not within function)
+- `print`: Print using `fmt.Println()`
+
+---
+
+### Adding functionality:
+
+Adding functionality is simple and requires a call to `scpt.AddFuncs()` or `scpt.AddVars()`. Here are some examples:
+
+```go
+scpt.AddFuncs(scpt.FuncMap{
+	"my-function": myFunction
+})
+```
+Where `myFunction` is:
+```go
+func myFunction(args map[string]interface{}) (interface{}, error) {
+	fmt.Println(args)
+	return nil, nil
+}
+```
+
+After the call to `scpt.AddFuncs()`, `my-function` can be used to run the function from within an scpt script. Variables work similarly.

ast.go

@@ -1,25 +1,18 @@
-/*
-	Copyright (c) 2021 Arsen Musayelyan
-
-	Permission is hereby granted, free of charge, to any person obtaining a copy
-	of this software and associated documentation files (the "Software"), to deal
-	in the Software without restriction, including without limitation the rights
-	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-	copies of the Software, and to permit persons to whom the Software is
-	furnished to do so, subject to the following conditions:
-
-	The above copyright notice and this permission notice shall be included in all
-	copies or substantial portions of the Software.
-*/
-
 package scpt
 
 import (
+	"bytes"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"github.com/alecthomas/participle/lexer"
 )
 
+var loopRunning bool
+var breakLoop bool
+var funcRunning bool
+var retValue interface{} = nil
+
 // AST stores the root of the Abstract Syntax Tree for scpt
 type AST struct {
 	Pos      lexer.Position
@@ -41,29 +34,229 @@ func (ast *AST) Execute() error {
 	return nil
 }
 
+func (ast *AST) Dump() ([]byte, error) {
+	return json.Marshal(ast)
+}
+
+func (ast *AST) DumpPretty() ([]byte, error) {
+	buf := bytes.NewBuffer([]byte{})
+	enc := json.NewEncoder(buf)
+	enc.SetIndent("", "    ")
+	err := enc.Encode(ast)
+	if err != nil {
+		return buf.Bytes(), err
+	}
+	return buf.Bytes(), nil
+}
+
+func LoadAST(data []byte) (*AST, error) {
+	var ast AST
+	err := json.Unmarshal(data, &ast)
+	if err != nil {
+		return nil, err
+	}
+	return &ast, nil
+}
+
+// Execute a variable declaration
+func executeVarCmd(Var *Var) error {
+	// Parse value of variable
+	val, err := ParseValue(Var.Value)
+	if err != nil {
+		return fmt.Errorf("%s: %s", Var.Value.Pos, err)
+	}
+	// If value of variable is a function call
+	if IsFuncCall(val) {
+		// Assert type of val as *FuncCall
+		Call := val.(*FuncCall)
+		// Set variable value to function return value
+		Vars[Var.Key], err = CallFunction(Call)
+		if err != nil {
+			return fmt.Errorf("%s: %s", Var.Value.Pos, err)
+		}
+	} else if Var.Index != nil {
+		// If variable definition has an associated index, get index value
+		index, err := callIfFunc(ParseValue(Var.Index))
+		if err != nil {
+			return fmt.Errorf("%s: %s", Var.Index.Pos, err)
+		}
+		// Attempt to get the variable from Vars and assert it as a []interface{}
+		slc, ok := Vars[Var.Key].([]interface{})
+		// If assertion successful
+		if ok {
+			// Assert index value as a 64-bit float
+			indexInt, ok := index.(float64)
+			if !ok {
+				return fmt.Errorf("%s: %s", Var.Pos, "variable "+Var.Key+" does not exist or is not an array")
+			}
+			// Set integer index of interface{} slice to value
+			slc[int64(indexInt)] = val
+		} else {
+			// If slice assertion unsuccessful, attempt to assert as map[interface{}]interface{}
+			iMap, ok := Vars[Var.Key].(map[interface{}]interface{})
+			if !ok {
+				return fmt.Errorf("%s: %s", Var.Pos, "variable "+Var.Key+" does not exist or is not a map")
+			}
+			// Set index of interface{} to interface{} map to value
+			iMap[index] = val
+		}
+	} else {
+		// If value is not a function call, set variable to parsed value
+		Vars[Var.Key] = val
+	}
+	return nil
+}
+
+// Execute an if statement
+func executeIfCmd(If *If) error {
+	// Get condition value
+	condVal, err := callIfFunc(ParseValue(If.Condition))
+	if err != nil {
+		return fmt.Errorf("%s: %s", If.Condition.Pos, err)
+	}
+	// Attempt to assert condition type as bool
+	condBool, ok := condVal.(bool)
+	if !ok {
+		return errors.New("condition must be a boolean")
+	}
+	// If condition is true
+	if condBool {
+		// For each inner command
+		for _, InnerCmd := range If.InnerCmds {
+			// Execute command recursively
+			err := executeCmd(InnerCmd)
+			if err != nil {
+				return fmt.Errorf("%s: %s", InnerCmd.Pos, err)
+			}
+		}
+	}
+	return nil
+}
+
+// Execute a repeat loop
+func executeRptLoop(rptLoop *RptLoop) error {
+	// Set loopRunning to true to allow break
+	loopRunning = true
+	// Run for loop with correct amount of iterations
+rpt:
+	for i := 0; i < *rptLoop.Times; i++ {
+		// If user requested index variable via "{ var in ... }"
+		if rptLoop.IndexVar != nil {
+			// Set requested variable name to index
+			Vars[*rptLoop.IndexVar] = i
+		}
+		// For each command within the loop
+		for _, InnerCmd := range rptLoop.InnerCmds {
+			// Execute command recursively
+			err := executeCmd(InnerCmd)
+			if err != nil {
+				return fmt.Errorf("%s: %s", InnerCmd.Pos, err)
+			}
+			// If breakLoop set to true
+			if breakLoop {
+				// Reset breakLoop
+				breakLoop = false
+				break rpt
+			}
+		}
+	}
+	// Remove index variable if existent
+	delete(Vars, *rptLoop.IndexVar)
+	// Reset loopRunning
+	loopRunning = false
+	return nil
+}
+
+// Execute a while loop
+func executeWhlLoop(whlLoop *WhlLoop) error {
+	loopRunning = true
+	// Get condition value
+	condVal, err := callIfFunc(ParseValue(whlLoop.Condition))
+	if err != nil {
+		return fmt.Errorf("%s: %s", whlLoop.Condition.Pos, err)
+	}
+	// Attempt to assert condition type as bool
+	condBool, ok := condVal.(bool)
+	if !ok {
+		return errors.New("condition must be a boolean")
+	}
+	// Run for loop if condition is true
+whl:
+	for condBool {
+		// For each inner command
+		for _, InnerCmd := range whlLoop.InnerCmds {
+			// Execute command recursively
+			err := executeCmd(InnerCmd)
+			if err != nil {
+				return fmt.Errorf("%s: %s", InnerCmd.Pos, err)
+			}
+			// If breakLoop set to true
+			if breakLoop {
+				// Reset breakLoop
+				breakLoop = false
+				break whl
+			}
+			// Get condition value
+			condVal, err = callIfFunc(ParseValue(whlLoop.Condition))
+			if err != nil {
+				return fmt.Errorf("%s: %s", whlLoop.Condition.Pos, err)
+			}
+			// Attempt to assert condition type as bool and update its value
+			condBool, ok = condVal.(bool)
+			if !ok {
+				return errors.New("condition must be a boolean")
+			}
+		}
+	}
+	loopRunning = false
+	return nil
+}
+
+// Execute a function definition
+func executeFuncDef(def *FuncDef) error {
+	// Set requested function name in Funcs
+	Funcs[*def.Name] = func(args map[string]interface{}) (interface{}, error) {
+		funcRunning = true
+		// Create new empty map[interface{}]interface{}
+		argIMap := map[interface{}]interface{}{}
+		// Convert args map[string]interface{} to map[interface{}]interface{}
+		for key, value := range args {
+			argIMap[key] = value
+		}
+		// Set variable _args to the args map[interface{}]interface{}
+		Vars["_args"] = argIMap
+		// For each command within the definition
+		for _, InnerCmd := range def.InnerCmds {
+			// Execute command recursively
+			err := executeCmd(InnerCmd)
+			if err != nil {
+				return nil, fmt.Errorf("%s: %s", InnerCmd.Pos, err)
+			}
+			if retValue != nil {
+				ret := retValue
+				retValue = nil
+				funcRunning = false
+				return ret, nil
+			}
+		}
+		// Remove args variable from Vars
+		delete(Vars, "_args")
+		funcRunning = false
+		return nil, nil
+	}
+	return nil
+}
+
 // Parse and execute command
 func executeCmd(cmd *Command) error {
 	// If parsing variables
 	if cmd.Vars != nil {
 		// For each variable
 		for _, Var := range cmd.Vars {
-			// Parse value of variable
-			val, err := ParseValue(Var.Value)
+			// Attempt to execute the variable command
+			err := executeVarCmd(Var)
 			if err != nil {
-				return fmt.Errorf("%s: %s", Var.Value.Pos, err)
-			}
-			// If value of variable is a function call
-			if IsFuncCall(val) {
-				// Assert type of val as *FuncCall
-				Call := val.(*FuncCall)
-				// Set variable value to function return value
-				Vars[Var.Key], err = CallFunction(Call)
-				if err != nil {
-					return fmt.Errorf("%s: %s", Var.Value.Pos, err)
-				}
-			} else {
-				// If value is not a function call, set variable value to parsed value
-				Vars[Var.Key] = val
+				return err
 			}
 		}
 	} else if cmd.Calls != nil {
@@ -75,45 +268,46 @@ func executeCmd(cmd *Command) error {
 				return fmt.Errorf("%s: %s", Call.Pos, err)
 			}
 		}
+	} else if cmd.Goroutines != nil {
+		// For each function call
+		for _, goroutine := range cmd.Goroutines {
+			// Attempt to call function
+			go CallFunction(goroutine.Call)
+		}
 	} else if cmd.Ifs != nil {
 		// For each if statement
 		for _, If := range cmd.Ifs {
-			// Get condition value
-			condVal, err := callIfFunc(ParseValue(If.Condition))
+			// Attempt to execute the if command
+			err := executeIfCmd(If)
 			if err != nil {
-				return fmt.Errorf("%s: %s", If.Condition.Pos, err)
-			}
-			// Attempt to assert condition type as bool
-			condBool, ok := condVal.(bool)
-			if !ok {
-				return errors.New("condition must be a boolean")
-			}
-			// If condition is true
-			if condBool {
-				// For each inner command
-				for _, InnerCmd := range If.InnerCmds {
-					// Execute command recursively
-					err := executeCmd(InnerCmd)
-					if err != nil {
-						return fmt.Errorf("%s: %s", InnerCmd.Pos, err)
-					}
-				}
+				return err
 			}
 		}
 	} else if cmd.RptLoops != nil {
 		// For each repeat loop
 		for _, RptLoop := range cmd.RptLoops {
-			for i:=0;i<*RptLoop.Times;i++ {
-				if RptLoop.IndexVar != nil {
-					Vars[*RptLoop.IndexVar] = i
-				}
-				for _, InnerCmd := range RptLoop.InnerCmds {
-					// Execute command recursively
-					err := executeCmd(InnerCmd)
-					if err != nil {
-						return fmt.Errorf("%s: %s", InnerCmd.Pos, err)
-					}
-				}
+			// Attempt to execute the repeat loop
+			err := executeRptLoop(RptLoop)
+			if err != nil {
+				return err
+			}
+		}
+	} else if cmd.WhlLoops != nil {
+		// For each while loop
+		for _, WhlLoop := range cmd.WhlLoops {
+			// Attempt to execute the while loop
+			err := executeWhlLoop(WhlLoop)
+			if err != nil {
+				return err
+			}
+		}
+	} else if cmd.Defs != nil {
+		// For each function definition
+		for _, Def := range cmd.Defs {
+			// Attempt to execute the function definition
+			err := executeFuncDef(Def)
+			if err != nil {
+				return err
 			}
 		}
 	}
@@ -122,58 +316,28 @@ func executeCmd(cmd *Command) error {
 
 // Command stores any commands encountered while parsing a script
 type Command struct {
-	Pos    lexer.Position
-	Tokens []lexer.Token
-	Vars   []*Var      `( @@`
-	Ifs    []*If       `| @@`
-	RptLoops []*RptLoop`| @@`
-	Calls  []*FuncCall `| @@)`
-}
-
-// If stores any if statements encountered while parsing a script
-type If struct {
-	Pos       lexer.Position
-	Condition *Value     `"if" @@ "{"`
-	InnerCmds []*Command `@@* "}"`
-}
-
-type RptLoop struct {
-	Pos       lexer.Position
-	Times     *int     `"repeat" @Number "times" "{"`
-	IndexVar *string `(@Ident "in")?`
-	InnerCmds []*Command `@@* "}"`
-}
-
-// FuncCall stores any function calls encountered while parsing a script
-type FuncCall struct {
-	Pos  lexer.Position
-	Name string `@Ident @("-" Ident)*`
-	Args []*Arg `@@*`
-}
-
-// Arg stores arguments for function calls
-type Arg struct {
-	Pos   lexer.Position
-	Key   string `("with" @Ident)?`
-	Value *Value `@@`
-}
-
-// Var stores any variables encountered while parsing a script
-type Var struct {
-	Pos   lexer.Position
-	Key   string `"set" @Ident "to"`
-	Value *Value `@@`
+	Pos        lexer.Position
+	Vars       []*Var       `( @@`
+	Ifs        []*If        `| @@`
+	RptLoops   []*RptLoop   `| @@`
+	WhlLoops   []*WhlLoop   `| @@`
+	Defs       []*FuncDef   `| @@`
+	Goroutines []*Goroutine `| @@`
+	Calls      []*FuncCall  `| @@ )`
 }
 
 // Value stores any literal values encountered while parsing a script
 type Value struct {
-	Pos    lexer.Position
-	String *string     `  @String`
-	Number *float64    `| @Number`
-	Bool   *Bool       `| @("true" | "false")`
-	SubCmd *FuncCall   `| "(" @@ ")"`
-	VarVal *string     `| "$" @Ident`
-	Expr   *Expression `| "{" @@ "}"`
+	Pos      lexer.Position
+	String   *string      `  @String`
+	Number   *float64     `| @Number`
+	Bool     *Bool        `| @("true" | "false")`
+	SubCmd   *FuncCall    `| "(" @@ ")"`
+	VarVal   *VarVal      `| @@`
+	Expr     *Expression  `| "{" @@ "}"`
+	Map      []*MapKVPair `| "[" (@@ ("," @@)* )? "]"`
+	Array    []*Value     `| "[" (@@ ("," @@)* )? "]"`
+	Opposite *Value       `| "!" @@`
 }
 
 // Bool stores boolean values encountered while parsing a script.
@@ -188,6 +352,31 @@ func (b *Bool) Capture(values []string) error {
 	return nil
 }
 
+// FuncCall stores any function calls encountered while parsing a script
+type FuncCall struct {
+	Pos  lexer.Position
+	Name string `@Ident @("-" Ident)*`
+	Args []*Arg `@@*`
+}
+
+type Goroutine struct {
+	Pos  lexer.Position
+	Call *FuncCall `"go" @@`
+}
+
+// Arg stores arguments for function calls
+type Arg struct {
+	Pos   lexer.Position
+	Key   string `("with" @Ident)?`
+	Value *Value `@@`
+}
+
+// VarVal stores any references to a variable encountered while parsing a script
+type VarVal struct {
+	Name  *string `"$" @Ident`
+	Index *Value  `("[" @@ "]")?`
+}
+
 // Expression stores any expressions encountered while parsing a
 // script for later evaluation
 type Expression struct {
@@ -201,3 +390,46 @@ type ExprRightSeg struct {
 	Op    string `@Operator`
 	Right *Value `@@`
 }
+
+// MapKVPair stores any key/value pairs encountered while parsing map literals
+type MapKVPair struct {
+	Key   *Value `@@`
+	Value *Value `":" @@`
+}
+
+// FuncDef stores any function definitions encountered while parsing a script
+type FuncDef struct {
+	Pos       lexer.Position
+	Name      *string    `"define" @Ident @("-" Ident)* "{"`
+	InnerCmds []*Command `@@* "}"`
+}
+
+// Var stores any variables encountered while parsing a script
+type Var struct {
+	Pos   lexer.Position
+	Key   string `"set" @Ident`
+	Index *Value `("[" @@ "]")?`
+	Value *Value `"to" @@`
+}
+
+// If stores any if statements encountered while parsing a script
+type If struct {
+	Pos       lexer.Position
+	Condition *Value     `"if" @@ "{"`
+	InnerCmds []*Command `@@* "}"`
+}
+
+// RptLoop stores any repeat loops encountered while parsing a script
+type RptLoop struct {
+	Pos       lexer.Position
+	Times     *int       `"repeat" @Number "times" "{"`
+	IndexVar  *string    `(@Ident "in")?`
+	InnerCmds []*Command `@@* "}"`
+}
+
+// WhlLoop stores any while loops encountered while parsing a script
+type WhlLoop struct {
+	Pos       lexer.Position
+	Condition *Value     `"loop" "while" @@ "{"`
+	InnerCmds []*Command `@@* "}"`
+}

cmd/scpt/funcs.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"github.com/gen2brain/dlgs"
+	"os"
+	"os/exec"
+)
+
+// Default function to display a dialog
+func displayDialog(args map[string]interface{}) (interface{}, error) {
+	// Get title
+	title, ok := args["title"]
+	if !ok {
+		return nil, errors.New("title not provided")
+	}
+	// Get unnamed argument as text
+	text, ok := args[""]
+	if !ok {
+		return nil, errors.New("text not provided")
+	}
+	// Display correct dialog based on given type
+	switch args["type"] {
+	case "yesno":
+		// Display yes or no dialog, returning bool based on user input
+		return dlgs.Question(fmt.Sprint(title), fmt.Sprint(text), true)
+	case "info":
+		// Display info dialog, returning bool based on success
+		return dlgs.Info(fmt.Sprint(title), fmt.Sprint(text))
+	case "error":
+		// Display error dialog, returning bool based on success
+		return dlgs.Error(fmt.Sprint(title), fmt.Sprint(text))
+	case "entry":
+		// Check if default text given
+		defaultText, ok := args["default"]
+		if !ok {
+			// Set to empty if not given
+			defaultText = ""
+		}
+		// Display entry dialog
+		input, _, err := dlgs.Entry(fmt.Sprint(title), fmt.Sprint(text), fmt.Sprint(defaultText))
+		// Return user input
+		return input, err
+	default:
+		// If type unknown, return error
+		return nil, fmt.Errorf("unknown dialog type: %v", args["type"])
+	}
+}
+
+// Default function to run a shell script using `sh -c`
+func doShellScript(args map[string]interface{}) (interface{}, error) {
+	// Get unnamed argument and assert its type as string
+	script, ok := args[""].(string)
+	// If assertion successful
+	if ok {
+		// Create new exec.Cmd containing `sh -c <script>`
+		cmd := exec.Command("sh", "-c", script)
+		// Set command I/O
+		cmd.Stdout = os.Stdout
+		cmd.Stdin = os.Stdin
+		cmd.Stderr = os.Stderr
+		// Run command
+		_ = cmd.Run()
+		return "", nil
+	} else {
+		return nil, errors.New("script not provided")
+	}
+}

cmd/scpt/main.go

@@ -1,30 +1,79 @@
 package main
 
 import (
+	"errors"
 	"flag"
+	"fmt"
 	"gitea.arsenm.dev/Arsen6331/scpt"
+	"io/ioutil"
 	"log"
 	"os"
 )
 
 func main() {
-	filePath := flag.String("file", "", "File to parse")
+	useStdin := flag.Bool("stdin", false, "Parse STDIN")
+	dumpAST := flag.Bool("dump-ast", false, "Dump the AST as JSON to STDOUT and quit")
+	loadAST := flag.String("load-ast", "", "Load JSON AST from specified file and execute it")
 	flag.Parse()
 
-	if *filePath == "" {
-		log.Fatalln("Use --file to specify a file to parse")
+	var ast *scpt.AST
+
+	if *loadAST != "" {
+		data, err := ioutil.ReadFile(*loadAST)
+		if err != nil {
+			log.Fatalln("Error opening specified file:", err)
+		}
+		ast, err = scpt.LoadAST(data)
+		if err != nil {
+			log.Fatalln("Error loading AST:", err)
+		}
+	} else if *useStdin {
+		var err error
+		ast, err = scpt.Parse(os.Stdin)
+		if err != nil {
+			log.Fatalln("Error parsing STDIN:", err)
+		}
+	} else {
+		if flag.NArg() < 1 {
+			log.Fatalln("Filepath or --stdin required")
+		}
+		filePath := flag.Args()[0]
+		file, err := os.Open(filePath)
+		if err != nil {
+			log.Fatalln("Error opening specified file:", err)
+		}
+		ast, err = scpt.Parse(file)
+		if err != nil {
+			log.Fatalln("Error parsing file:", err)
+		}
 	}
 
-	file, err := os.Open(*filePath)
-	if err != nil {
-		log.Fatalln("Error opening specified file:", err)
+	if *dumpAST {
+		data, err := ast.DumpPretty()
+		if err != nil {
+			log.Fatalln("Error dumping AST:", err)
+		}
+		fmt.Println(string(data))
+		os.Exit(0)
 	}
-	ast, err := scpt.Parse(file)
-	if err != nil {
-		log.Fatalln("Error parsing file:", err)
-	}
-	err = ast.Execute()
+
+	scpt.AddFuncs(scpt.FuncMap{
+		"print":           scptPrint,
+		"display-dialog":  displayDialog,
+		"do-shell-script": doShellScript,
+	})
+
+	err := ast.Execute()
 	if err != nil {
 		log.Fatalln("Error executing script:", err)
 	}
 }
+
+func scptPrint(args map[string]interface{}) (interface{}, error) {
+	val, ok := args[""]
+	if !ok {
+		return nil, errors.New("print requires an unnamed argument")
+	}
+	fmt.Println(val)
+	return nil, nil
+}

defaults.go

@@ -1,91 +1,119 @@
-/*
-	Copyright (c) 2021 Arsen Musayelyan
-
-	Permission is hereby granted, free of charge, to any person obtaining a copy
-	of this software and associated documentation files (the "Software"), to deal
-	in the Software without restriction, including without limitation the rights
-	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-	copies of the Software, and to permit persons to whom the Software is
-	furnished to do so, subject to the following conditions:
-
-	The above copyright notice and this permission notice shall be included in all
-	copies or substantial portions of the Software.
-*/
-
 package scpt
 
 import (
 	"errors"
 	"fmt"
-	"github.com/gen2brain/dlgs"
 	"os"
-	"os/exec"
+	"strconv"
 )
 
-// Default function to display a dialog
-func displayDialog(args map[string]interface{}) (interface{}, error) {
-	// Get title
-	title, ok := args["title"]
-	if !ok {
-		return nil, errors.New("title not provided")
-	}
-	// Get unnamed argument as text
-	text, ok := args[""]
-	if !ok {
-		return nil, errors.New("text not provided")
-	}
-	// Display correct dialog based on given type
-	switch args["type"] {
-	case "yesno":
-		// Display yes or no dialog, returning bool based on user input
-		return dlgs.Question(fmt.Sprint(title), fmt.Sprint(text), true)
-	case "info":
-		// Display info dialog, returning bool based on success
-		return dlgs.Info(fmt.Sprint(title), fmt.Sprint(text))
-	case "error":
-		// Display error dialog, returning bool based on success
-		return dlgs.Error(fmt.Sprint(title), fmt.Sprint(text))
-	case "entry":
-		// Check if default text given
-		defaultText, ok := args["default"]
-		if !ok {
-			// Set to empty if not given
-			defaultText = ""
-		}
-		// Display entry dialog
-		input, _, err := dlgs.Entry(fmt.Sprint(title), fmt.Sprint(text), fmt.Sprint(defaultText))
-		// Return user input
-		return input, err
-	default:
-		// If type unknown, return error
-		return nil, fmt.Errorf("unknown dialog type: %v", args["type"])
-	}
-}
-
-// Default function to run a shell script using `sh -c`
-func doShellScript(args map[string]interface{}) (interface{}, error) {
-	// Get unnamed argument and assert its type as string
-	script, ok := args[""].(string)
-	// If assertion successful
-	if ok {
-		// Create new exec.Cmd containing `sh -c <script>`
-		cmd := exec.Command("sh", "-c", script)
-		// Set command I/O
-		cmd.Stdout = os.Stdout
-		cmd.Stdin = os.Stdin
-		cmd.Stderr = os.Stderr
-		// Run command
-		_ = cmd.Run()
-		return "", nil
-	} else {
-		return nil, errors.New("script not provided")
-	}
+// Vars stores any variables set during script runtime
+var Vars = map[string]interface{}{}
+
+// FuncMap is a map of strings mapped to suitable script functions
+type FuncMap map[string]func(map[string]interface{}) (interface{}, error)
+
+// Funcs stores the functions allowed for use in a script
+var Funcs = FuncMap{
+	"str":    toString,
+	"num":    parseNumber,
+	"bool":   parseBool,
+	"break":  setBreakLoop,
+	"append": appendArray,
+	"exit":   scptExit,
+	"return": setReturn,
+	"print":  scptPrint,
 }
 
+// Default function to convert unnamed argument to a string using fmt.Sprint
 func toString(args map[string]interface{}) (interface{}, error) {
 	val, ok := args[""]
 	if !ok {
 		return nil, errors.New("no value provided")
 	}
 	return fmt.Sprint(val), nil
-}
+}
+
+// Default function to parse unnamed argument to a number using strconv.ParseFloat
+func parseNumber(args map[string]interface{}) (interface{}, error) {
+	val, ok := args[""].(string)
+	if !ok {
+		return nil, errors.New("no value provided")
+	}
+	return strconv.ParseFloat(val, 64)
+}
+
+// Default function to parse unnamed argument to a boolean using strconv.ParseBool
+func parseBool(args map[string]interface{}) (interface{}, error) {
+	val, ok := args[""].(string)
+	if !ok {
+		return nil, errors.New("no value provided")
+	}
+	return strconv.ParseBool(val)
+}
+
+// Default function to set the breakLoop variable to true, breaking any loops that may be running
+func setBreakLoop(_ map[string]interface{}) (interface{}, error) {
+	// If a loop is running
+	if loopRunning {
+		// Set breakLoop to true, breaking the loop on next cycle
+		breakLoop = true
+	} else {
+		return nil, errors.New("break not inside loop")
+	}
+	return nil, nil
+}
+
+// Default function to set the breakLoop variable to true, breaking any loops that may be running
+func setReturn(args map[string]interface{}) (interface{}, error) {
+	// If a loop is running
+	if funcRunning {
+		// Set breakLoop to true, breaking the loop on next cycle
+		retValue = args[""]
+	} else {
+		return nil, errors.New("return not inside function")
+	}
+	return nil, nil
+}
+
+func scptExit(args map[string]interface{}) (interface{}, error) {
+	exitCode, ok := args[""].(float64)
+	if !ok {
+		return nil, errors.New("exit requires an unnamed number argument")
+	}
+	os.Exit(int(exitCode))
+	return nil, nil
+}
+
+// Default function that returns an array with an appended element
+func appendArray(args map[string]interface{}) (interface{}, error) {
+	// Attempt to get unnamed argument and assert as []interface{}
+	val, ok := args[""].([]interface{})
+	if !ok {
+		return nil, errors.New("cannot append to non-array object")
+	}
+	// Attempt to get items argument and assert as []interface{}
+	items, ok := args["items"].([]interface{})
+	if !ok {
+		return nil, errors.New("items argument invalid or not provided")
+	}
+	// For every item in items argument
+	for _, item := range items {
+		// Append to unnamed argument
+		val = append(val, item)
+	}
+	// Return appended unnamed argument
+	return val, nil
+}
+
+// Print message via fmt.Println
+func scptPrint(args map[string]interface{}) (interface{}, error) {
+	// Get message
+	val, ok := args[""]
+	if !ok {
+		return nil, errors.New("print requires an unnamed argument")
+	}
+	// Print message
+	fmt.Println(val)
+	return nil, nil
+}

go.sum

@@ -1,4 +1,3 @@
-github.com/DATA-DOG/go-sqlmock v1.3.3 h1:CWUqKXe0s8A2z6qCgkP4Kru7wC11YoAnoupUKFDnH08=
 github.com/DATA-DOG/go-sqlmock v1.3.3/go.mod h1:f/Ixk793poVmq4qj/V1dPUg2JEAKC73Q5eFN3EC/SaM=
 github.com/alecthomas/participle v0.7.1 h1:2bN7reTw//5f0cugJcTOnY/NYZcWQOaajW+BwZB5xWs=
 github.com/alecthomas/participle v0.7.1/go.mod h1:HfdmEuwvr12HXQN44HPWXR0lHmVolVYe4dyL6lQ3duY=
@@ -6,66 +5,38 @@ github.com/alecthomas/repr v0.0.0-20181024024818-d37bc2a10ba1 h1:GDQdwm/gAcJcLAK
 github.com/alecthomas/repr v0.0.0-20181024024818-d37bc2a10ba1/go.mod h1:xTS7Pm1pD1mvyM075QCDSRqH6qRLXylzS24ZTpRiSzQ=
 github.com/antonmedv/expr v1.8.9 h1:O9stiHmHHww9b4ozhPx7T6BK7fXfOCHJ8ybxf0833zw=
 github.com/antonmedv/expr v1.8.9/go.mod h1:5qsM3oLGDND7sDmQGDXHkYfkjYMUX14qsgqmHhwGEk8=
-github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e h1:Wf6HqHfScWJN9/ZjdUKyjop4mf3Qdd+1TvvltAvM3m8=
-github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
 github.com/davecgh/go-spew v0.0.0-20161028175848-04cdfd42973b/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/gdamore/encoding v1.0.0 h1:+7OoQ1Bc6eTm5niUzBa0Ctsh6JbMW6Ra+YNuAtDBdko=
 github.com/gdamore/encoding v1.0.0/go.mod h1:alR0ol34c49FCSBLjhosxzcPHQbf2trDkoo5dl+VrEg=
-github.com/gdamore/tcell v1.3.0 h1:r35w0JBADPZCVQijYebl6YMWWtHRqVEGt7kL2eBADRM=
 github.com/gdamore/tcell v1.3.0/go.mod h1:Hjvr+Ofd+gLglo7RYKxxnzCBmev3BzsS67MebKS4zMM=
 github.com/gen2brain/dlgs v0.0.0-20210222160047-2f436553172f h1:HPKrg4xeWLWOGAJGVJIYXWhVSdy2kaihuoSy7kBP7S4=
 github.com/gen2brain/dlgs v0.0.0-20210222160047-2f436553172f/go.mod h1:/eFcjDXaU2THSOOqLxOPETIbHETnamk8FA/hMjhg/gU=
 github.com/gopherjs/gopherjs v0.0.0-20210202160940-bed99a852dfe h1:rcf1P0fm+1l0EjG16p06mYLj9gW9X36KgdHJ/88hS4g=
 github.com/gopherjs/gopherjs v0.0.0-20210202160940-bed99a852dfe/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
 github.com/lucasb-eyer/go-colorful v1.0.2/go.mod h1:0MS4r+7BZKSJ5mw4/S5MPN+qHFF1fYclkSPilDOKW0s=
-github.com/lucasb-eyer/go-colorful v1.0.3 h1:QIbQXiugsb+q10B+MI+7DI1oQLdmnep86tWFlaaUAac=
 github.com/lucasb-eyer/go-colorful v1.0.3/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/mattn/go-runewidth v0.0.4/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
-github.com/mattn/go-runewidth v0.0.8 h1:3tS41NlGYSmhhe/8fhGRzc+z3AYCw1Fe1WAyLuujKs0=
 github.com/mattn/go-runewidth v0.0.8/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
-github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
-github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v0.0.0-20151028094244-d8ed2627bdf0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/rivo/tview v0.0.0-20200219210816-cd38d7432498 h1:4CFNy7/q7P06AsIONZzuWy7jcdqEmYQvOZ9FAFZdbls=
 github.com/rivo/tview v0.0.0-20200219210816-cd38d7432498/go.mod h1:6lkG1x+13OShEf0EaOCaTQYyB7d5nSbb181KtjlS+84=
-github.com/rivo/uniseg v0.1.0 h1:+2KBaVoUmb9XzDsrx/Ct0W/EYOSFf/nWTauy++DprtY=
 github.com/rivo/uniseg v0.1.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
-github.com/rs/xid v1.2.1 h1:mhH9Nq+C1fY2l1XIpgxIiUOfNpRBYH1kKcr+qfKgjRc=
-github.com/rs/xid v1.2.1/go.mod h1:+uKXf+4Djp6Md1KODXJxgGQPKngRmWyn10oCKFzNHOQ=
-github.com/rs/zerolog v1.20.0 h1:38k9hgtUBdxFwE34yS8rTHmHBa4eN16E4DJlv177LNs=
-github.com/rs/zerolog v1.20.0/go.mod h1:IzD0RJ65iWH0w97OQQebJEvTZYvsCUm9WVLWBQrJRjo=
-github.com/sanity-io/litter v1.2.0 h1:DGJO0bxH/+C2EukzOSBmAlxmkhVMGqzvcx/rvySYw9M=
 github.com/sanity-io/litter v1.2.0/go.mod h1:JF6pZUFgu2Q0sBZ+HSV35P8TVPI1TTzEwyu9FXAw2W4=
-github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v0.0.0-20161117074351-18a02ba4a312/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1 h1:nOGnQDM7FYENwehXlg/kFVnos3rEvtKTjRvOWSzb6H4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859 h1:R/3boaszxrf1GEUWTVDzSKVwLmSJpwZ1yqXm8j0v2QI=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200212091648-12a6c2dcc1e4 h1:sfkvUWPNGwSV+8/fNqctR5lS2AqCSqYwXdrjCxp/dXo=
 golang.org/x/sys v0.0.0-20200212091648-12a6c2dcc1e4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/tools v0.0.0-20190828213141-aed303cbaa74 h1:4cFkmztxtMslUX2SctSl+blCyXfpzhGOy9LhKAqSMA4=
-golang.org/x/tools v0.0.0-20190828213141-aed303cbaa74/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7 h1:9zdDQZ7Thm29KFXgAX/+yaf3eVbP7djjWp/dXAppNCc=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

lexer.go

@@ -7,11 +7,11 @@ import (
 
 // Create custom stateful regex lexer
 var scptLexer = lexer.Must(stateful.NewSimple([]stateful.Rule{
-	{"Ident", `[a-zA-Z]\w*`, nil},
+	{"Ident", `[a-zA-Z_]\w*`, nil},
 	{"String", `"[^"]*"`, nil},
 	{"Number", `(?:\d*\.)?\d+`, nil},
-	{"Punct", `[-[!@$&()_{}\|:;"',.?/]|]`, nil},
+	{"Punct", `[![@$&(){}\|:;"',.?]|]`, nil},
 	{"Whitespace", `[ \t\r\n]+`, nil},
-	{"Comment", `#[^\n]+`, nil},
-	{"Operator", `(>=|<=|>|<|==|!=)|[-+*/^%]`, nil},
+	{"Comment", `(###(.|\n)+###|#[^\n]+)`, nil},
+	{"Operator", `(>=|<=|>|<|==|!=)|[-+*%/^]`, nil},
 }))

scpt.go

@@ -1,17 +1,3 @@
-/*
-	Copyright (c) 2021 Arsen Musayelyan
-
-	Permission is hereby granted, free of charge, to any person obtaining a copy
-	of this software and associated documentation files (the "Software"), to deal
-	in the Software without restriction, including without limitation the rights
-	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-	copies of the Software, and to permit persons to whom the Software is
-	furnished to do so, subject to the following conditions:
-
-	The above copyright notice and this permission notice shall be included in all
-	copies or substantial portions of the Software.
-*/
-
 // Package scpt provides an interpreter for my simple applescript-like
 // scripting language
 package scpt
@@ -26,19 +12,6 @@ import (
 	"strings"
 )
 
-// Vars stores any variables set during script runtime
-var Vars = map[string]interface{}{}
-
-// FuncMap is a map of strings mapped to suitable script functions
-type FuncMap map[string]func(map[string]interface{}) (interface{}, error)
-
-// Funcs stores the functions allowed for use in a script
-var Funcs = FuncMap{
-	"display-dialog":  displayDialog,
-	"do-shell-script": doShellScript,
-	"string": toString,
-}
-
 // AddFuncs adds all functions from the provided FuncMap into
 // the Funcs variable
 func AddFuncs(fnMap FuncMap) {
@@ -95,62 +68,165 @@ func ParseValue(val *Value) (interface{}, error) {
 		// Return reference to subcommand
 		return val.SubCmd, nil
 	} else if val.VarVal != nil {
-		// Return value of provided key
-		return Vars[*val.VarVal], nil
-	} else if val.Expr != nil {
-		// Parse value of left side of expression
-		left, _ := callIfFunc(ParseValue(val.Expr.Left))
-		// If value is string, requote
-		if isStr(left) {
-			left = requoteStr(left.(string))
-		}
-		// Create new nil string
-		var right string
-		// For every right segment
-		for _, segment := range val.Expr.RightSegs {
-			// Parse value of right segment, calling it if it is a function
-			rVal, _ := callIfFunc(ParseValue(segment.Right))
-			// If value is string, requote
-			if isStr(rVal) {
-				rVal = requoteStr(rVal.(string))
+		// If variable access contains index
+		if val.VarVal.Index != nil {
+			// Get index value
+			index, err := callIfFunc(ParseValue(val.VarVal.Index))
+			if err != nil {
+				return nil, err
 			}
-			// Append right segment to right string
-			right = right + fmt.Sprintf(
-				" %s %v",
-				segment.Op,
-				rVal,
-			)
+			// Get requested variable and attempt to assert as []interface{}
+			slc, ok := Vars[*val.VarVal.Name].([]interface{})
+			// If assertion successful
+			if ok {
+				// Attempt to assert index as a 64-bit float
+				indexFlt, ok := index.(float64)
+				if !ok {
+					return nil, errors.New("array index must be a number")
+				}
+				// If requested index is out of range, return error
+				if int64(len(slc)) <= int64(indexFlt) {
+					return nil, fmt.Errorf("index %d is out of range with length %d", *val.VarVal.Index, len(slc))
+				}
+				// Return value at requested index of requested variable
+				return slc[int64(indexFlt)], nil
+			} else {
+				// If assertion unsuccessful, attempt to assert as a map[interface{}]interface{}
+				iMap, ok := Vars[*val.VarVal.Name].(map[interface{}]interface{})
+				if !ok {
+					return nil, errors.New("variable " + *val.VarVal.Name + " does not exist or is not a map")
+				}
+				// Attempt to get value at requested key
+				val, ok := iMap[index]
+				if !ok {
+					return nil, fmt.Errorf("index %v does not exist in map", index)
+				}
+				// Return value at key with no error
+				return val, nil
+			}
+		} else {
+			// If index is absent, attempt to get variable value from Vars
+			value, ok := Vars[*val.VarVal.Name]
+			if !ok {
+				return nil, errors.New("variable " + *val.VarVal.Name + " does not exist")
+			}
+			// Return value with no error
+			return value, nil
 		}
-		// Create string expression from segments and operator
-		exp := fmt.Sprintf(
-			"%v %s",
-			left,
-			right,
-		)
-		// Compile string expression
-		program, err := expr.Compile(strings.ReplaceAll(exp, "^", "**"))
+	} else if val.Expr != nil {
+		// If value is an expression, return evaluated expression
+		return evalExpr(*val.Expr)
+	} else if val.Array != nil {
+		// If value is an array, create new nil []interface{}
+		var iSlice []interface{}
+		// For each value in array
+		for _, value := range val.Array {
+			// Recursively parse value
+			iVal, err := callIfFunc(ParseValue(value))
+			if err != nil {
+				return nil, err
+			}
+			// Append value to []interface{}
+			iSlice = append(iSlice, iVal)
+		}
+		// Return []interface{]
+		return iSlice, nil
+	} else if val.Map != nil {
+		// If value is a map, create new empty map[interface{}]interface{}
+		iMap := map[interface{}]interface{}{}
+		// For each value in map
+		for _, value := range val.Map {
+			// Recursively parse value
+			iVal, err := ParseValue(value.Value)
+			if err != nil {
+				return nil, err
+			}
+			// Recursively parse key
+			iKey, err := ParseValue(value.Key)
+			if err != nil {
+				return nil, err
+			}
+			// Set key of map to value
+			iMap[iKey] = iVal
+		}
+		// Return map[interface{}]interface{}
+		return iMap, nil
+	} else if val.Opposite != nil {
+		value, err := callIfFunc(ParseValue(val.Opposite))
 		if err != nil {
 			return nil, err
 		}
-		// Run expression
-		out, err := expr.Run(program, Vars)
-		if err != nil {
-			return nil, err
+		boolean, ok := value.(bool)
+		if !ok {
+			return nil, errors.New("cannot take opposite of a non-boolean value")
 		}
-		// Return expression output value
-		return out, nil
+		return !boolean, nil
 	}
 	return nil, nil
 }
 
+// Evaluate given expression, returning its value and optionally an error
+func evalExpr(expression Expression) (interface{}, error) {
+	// Parse value of left side of expression
+	left, _ := callIfFunc(ParseValue(expression.Left))
+	// If value is string, requote
+	if isStr(left) {
+		left = quoteStr(left.(string))
+	}
+	// Create new nil string
+	var right string
+	// For every right gsegment
+	for _, segment := range expression.RightSegs {
+		// Parse value of right segment, calling it if it is a function
+		rVal, _ := callIfFunc(ParseValue(segment.Right))
+		// If value is string, requote
+		if isStr(rVal) {
+			rVal = quoteStr(rVal)
+		}
+		// Append right segment to right string
+		right = right + fmt.Sprintf(
+			" %s %v",
+			segment.Op,
+			rVal,
+		)
+	}
+	// Create string expression from segments and operator
+	exp := fmt.Sprintf(
+		"%v %s",
+		left,
+		right,
+	)
+	// Compile string expression
+	program, err := expr.Compile(strings.ReplaceAll(exp, "^", "**"))
+	if err != nil {
+		return nil, err
+	}
+	// Run expression
+	out, err := expr.Run(program, Vars)
+	if err != nil {
+		return nil, err
+	}
+	// Return expression output value
+	return out, nil
+}
+
 // Add quotes to an unquoted string
-func requoteStr(s string) string {
-	// Return quoted string
-	return `"` + s + `"`
+func quoteStr(s interface{}) string {
+	// If s is nil
+	if s == nil {
+		// Return empty quotes
+		return `""`
+	} else {
+		// Otherwise return formatted string using %v (any value)
+		return fmt.Sprintf(`"%v"`, s)
+	}
 }
 
 // Check if i is a string
 func isStr(i interface{}) bool {
+	if i == nil {
+		return true
+	}
 	// if type of input is string, return true
 	if reflect.TypeOf(i).String() == "string" {
 		return true
@@ -205,10 +281,7 @@ func UnwrapArgs(args []*Arg) (map[string]interface{}, error) {
 // IsFuncCall checks if val is a FuncCall struct
 func IsFuncCall(val interface{}) bool {
 	// If type of val is a pointer to FuncCall, return true
-	if reflect.TypeOf(val) == reflect.TypeOf(&FuncCall{}) {
-		return true
-	}
-	return false
+	return reflect.TypeOf(val) == reflect.TypeOf(&FuncCall{})
 }
 
 // CallFunction executes a given function call in the form of

scpt.yaml

@@ -0,0 +1,33 @@
+# This file is a syntax file for https://github.com/zyedidia/highlight
+# This file is also suitable for the micro text editor, to install, place in ~/.config/micro/syntax
+
+filetype: scpt
+
+detect:
+    filename: "\\.scpt$"
+
+rules:
+    - special: "\\b(bool|str|num|append)\\b"
+    - statement: "\\b(define|set|to|loop|while|if|repeat|times|in|)\\b"
+    - statement: "\\$"
+    - symbol.operator: "(>=|<=|>|<|==|!=)|[-+*%/^]"
+    - symbol.brackets: "([(){}]|\\[|\\])"
+
+    - constant.number: "\\b(?:\\d*\\.)?\\d+\\b"
+
+    - constant.string:
+        start: "\""
+        end: "\""
+        rules: []
+
+    - constant.bool: "\\b(true|false)\\b"
+
+    - comment:
+        start: "###"
+        end: "###"
+        rules: []
+
+    - comment:
+        start: "#"
+        end: "$"
+        rules: []

test.scpt

@@ -1,3 +1,5 @@
+#!/usr/bin/env scpt
+
 set y to (display-dialog "Hello" with title 12 with type "yesno")
 display-dialog "Goodbye" with title 21 with type "error"
 do-shell-script "notify-send Test Notification"
@@ -14,8 +16,61 @@ if {3 == 3} {
     }
 }
 
-do-shell-script "echo rpt"
-
 repeat 5 times { z in
-    do-shell-script {"echo " + (string $z)}
-}
+    print $z
+}
+
+print (str 10.5)
+
+if (bool "true") {
+    print "True"
+}
+
+###
+This is a multiline comment
+###
+
+# This is a single line comment
+
+set hi to ["test", 3]
+
+set hi[0] to "test2"
+
+print $hi[0]
+
+set hi to (append $hi with items [5, 4])
+
+print {$hi[2] + $hi[3]}
+
+set msi to [5: "hi", "hello": "world"]
+set msi[5] to "hello"
+print $msi[5]
+print $msi["hello"]
+
+set c to 0
+set f to true
+loop while $f {
+    set c to {$c + 1}
+    if {$c == 3} {
+        set f to false
+    }
+    print {"iter: " + (str $c)}
+}
+
+repeat 6 times { i in
+    print {"brktest: " + (str $i)}
+    if {$i == 3} {
+            break
+    }
+    print {"brktest: " + (str $i) + " (2)"}
+}
+
+define hello-x {
+    print {"Hello, " + $_args[""]}
+    return {"Hello, " + $_args[""]}
+    print "Something isn't right"
+}
+
+hello-x "Function"
+set f to (hello-x "World")
+print {"Returned: " + $f}