Made commands more powerful, added :load and :save

.vscode/settings.json

@@ -2,7 +2,9 @@
     "cSpell.words": [
         "autochurch",
         "freevar",
+        "mdel",
         "onefile",
+        "Packrat",
         "pyparsing",
         "runstatus",
         "subvar"

README.md

@@ -2,12 +2,11 @@
 
 
 ## Todo (pre-release):
- - Good command parsing (`:save`, `:load`, are a bare minimum)
  - $\alpha$-equivalence check
  - Prettyprint functions (combine args, rename bound variables)
  - Write a nice README
- - Delete macros
  - Handle or avoid recursion errors
+ - Fix colors
 
 ## Todo:
  - live syntax check
@@ -17,8 +16,8 @@
  - Warn when overwriting macro
  - Syntax highlighting: parenthesis, bound variables, macros, etc
  - Pin header to top of screen
- - Parser is a bit slow. Maybe we can do better?
+ - PyPi package
- - pypi package
+ - Smart alignment in all printouts
 
 ## Mention in Docs
  - lambda functions only work with single-letter arguments

lamb/__main__.py

@@ -4,34 +4,46 @@ from prompt_toolkit import print_formatted_text as printf
 from prompt_toolkit.formatted_text import FormattedText
 from prompt_toolkit.formatted_text import to_plain_text
 from prompt_toolkit.key_binding import KeyBindings
+from prompt_toolkit.lexers import Lexer
 
 from pyparsing import exceptions as ppx
 
-from lamb.parser import Parser
 import lamb.runner as runner
 import lamb.runstatus as rs
 import lamb.tokens as tokens
 import lamb.utils as utils
 
 
-# Replace "\" with a pretty "λ" in the prompt
+# Simple lexer for highlighting.
-bindings = KeyBindings()
+# Improve this later.
-@bindings.add("\\")
+class LambdaLexer(Lexer):
-def _(event):
+	def lex_document(self, document):
-	event.current_buffer.insert_text("λ")
+		def inner(line_no):
-
+			return [("class:text", str(document.lines[line_no]))]
-session = PromptSession(
+		return inner
-	message = FormattedText([
-		("#00FFFF", "~~> ")
-	]),
-	key_bindings = bindings
-)
 
 
 utils.show_greeting()
 
 
-r = runner.Runner()
+# Replace "\" with pretty "λ"s
+bindings = KeyBindings()
+@bindings.add("\\")
+def _(event):
+	event.current_buffer.insert_text("λ")
+
+
+r = runner.Runner(
+	prompt_session = PromptSession(
+		style = utils.style,
+		lexer = LambdaLexer(),
+		key_bindings = bindings
+	),
+
+	prompt_message = FormattedText([
+		("class:prompt", "~~> ")
+	]),
+)
 
 r.run_lines([
 	"T = λab.a",
@@ -52,7 +64,7 @@ r.run_lines([
 
 while True:
 	try:
-		i = session.prompt()
+		i = r.prompt()
 
 	# Catch Ctrl-C and Ctrl-D
 	except KeyboardInterrupt:
@@ -72,46 +84,44 @@ while True:
 	try:
 		x = r.run(i)
 	except ppx.ParseException as e:
-		l = len(to_plain_text(session.message))
+		l = len(to_plain_text(r.prompt_session.message))
 		printf(FormattedText([
-			("#FF0000", " "*(e.loc + l) + "^\n"),
+			("class:err", " "*(e.loc + l) + "^\n"),
-			("#FF0000", f"Syntax error at char {e.loc}."),
+			("class:err", f"Syntax error at char {e.loc}."),
-			("#FFFFFF", "\n")
+			("class:text", "\n")
 		]))
 		continue
 	except tokens.ReductionError as e:
 		printf(FormattedText([
-			("#FF0000", f"{e.msg}"),
+			("class:err", f"{e.msg}\n")
-			("#FFFFFF", "\n")
+		]), style = utils.style)
-		]))
 		continue
 
 	# If this line defined a macro, print nothing.
 	if isinstance(x, rs.MacroStatus):
 		printf(FormattedText([
-			("#FFFFFF", "Set "),
+			("class:text", "Set "),
-			("#FF00FF", x.macro_label),
+			("class:syn_macro", x.macro_label),
-			("#FFFFFF", " to "),
+			("class:text", " to "),
-			("#FFFFFF", str(x.macro_expr))
+			("class:text", str(x.macro_expr))
-		]))
+		]), style = utils.style)
 
 
 	if isinstance(x, rs.CommandStatus):
-		printf(x.formatted_text)
+		pass
 
 	# If this line was an expression, print reduction status
 	elif isinstance(x, rs.ReduceStatus):
 		printf(FormattedText([
-
+			("class:result_header", f"\nExit reason: "),
-			("#00FF00 bold", f"\nExit reason: "),
 			x.stop_reason.value,
 
-			("#00FF00 bold", f"\nReduction count: "),
+			("class:result_header", f"\nReduction count: "),
-			("#FFFFFF", str(x.reduction_count)),
+			("class:text", str(x.reduction_count)),
 
 
-			("#00FF00 bold", "\n\n    => "),
+			("class:result_header", "\n\n    => "),
-			("#FFFFFF", str(x.result)),
+			("class:text", str(x.result)),
-		]))
+		]), style = utils.style)
 
 	printf("")

lamb/commands.py

@@ -1,8 +1,12 @@
 from prompt_toolkit.formatted_text import FormattedText
 from prompt_toolkit.formatted_text import HTML
+from prompt_toolkit import print_formatted_text as printf
 from prompt_toolkit.shortcuts import clear as clear_screen
 
-from lamb.runstatus import CommandStatus
+import os.path
+
+from pyparsing import exceptions as ppx
+import lamb.runstatus as rs
 import lamb.utils as utils
 
 
@@ -16,100 +20,181 @@ def lamb_command(*, help_text: str):
 		help_texts[func.__name__] = help_text
 	return inner
 
-def run(command, runner):
+def run(command, runner) -> None:
-	return commands[command.name](command, runner)
+	if command.name not in commands:
+		printf(
+			FormattedText([
+				("class:warn", f"Unknown command \"{command.name}\"")
+			]),
+			style = utils.style
+		)
+	else:
+		commands[command.name](command, runner)
+
+
+@lamb_command(help_text = "Save macros to a file")
+def save(command, runner) -> None:
+	if len(command.args) != 1:
+		printf(
+			HTML(
+				"<err>Command <cmd_code>:save</cmd_code> takes exactly one argument.</err>"
+			),
+			style = utils.style
+		)
+		return
+
+	target = command.args[0]
+	if os.path.exists(target):
+		confirm = runner.prompt_session.prompt(
+			message = FormattedText([
+				("class:warn", "File exists. Overwrite? "),
+				("class:text", "[yes/no]: ")
+			])
+		).lower()
+
+		if confirm != "yes":
+			printf(
+				HTML(
+					"<err>Cancelled.</err>"
+				),
+				style = utils.style
+			)
+			return
+
+	with open(target, "w") as f:
+		f.write("\n".join(
+			[f"{n} = {e}" for n, e in runner.macro_table.items()]
+		))
+
+	printf(
+		HTML(
+			f"Wrote {len(runner.macro_table)} macros to <cmd_code>{target}</cmd_code>"
+		),
+		style = utils.style
+	)
+
+
+@lamb_command(help_text = "Load macros from a file")
+def load(command, runner):
+	if len(command.args) != 1:
+		printf(
+			HTML(
+				"<err>Command <cmd_code>:load</cmd_code> takes exactly one argument.</err>"
+			),
+			style = utils.style
+		)
+		return
+
+	target = command.args[0]
+	if not os.path.exists(target):
+		printf(
+			HTML(
+				f"<err>File {target} doesn't exist.</err>"
+			),
+			style = utils.style
+		)
+		return
+
+	with open(target, "r") as f:
+		lines = [x.strip() for x in f.readlines()]
+
+	for i in range(len(lines)):
+		l = lines[i]
+		try:
+			x = runner.run(l, macro_only = True)
+		except ppx.ParseException as e:
+			printf(
+				FormattedText([
+					("class:warn", f"Syntax error on line {i+1:02}: "),
+					("class:cmd_code", l[:e.loc]),
+					("class:err", l[e.loc]),
+					("class:cmd_code", l[e.loc+1:])
+				]),
+				style = utils.style
+			)
+		except rs.NotAMacro:
+			printf(
+				FormattedText([
+					("class:warn", f"Skipping line {i+1:02}: "),
+					("class:cmd_code", l),
+					("class:warn", f" is not a macro definition.")
+				]),
+				style = utils.style
+			)
+		else:
+			printf(
+				FormattedText([
+					("class:ok", f"Loaded {x.macro_label}: "),
+					("class:cmd_code", str(x.macro_expr))
+				]),
+				style = utils.style
+			)
+
+
 
 @lamb_command(help_text = "Delete a macro")
-def mdel(command, runner):
+def mdel(command, runner) -> None:
 	if len(command.args) != 1:
-		return CommandStatus(
+		printf(
-			formatted_text = HTML(
+			HTML(
-				"<red>Command <grey>:mdel</grey> takes exactly one argument.</red>"
+				"<err>Command <cmd_code>:mdel</cmd_code> takes exactly one argument.</err>"
-			)
+			),
+			style = utils.style
 		)
+		return
 
 	target = command.args[0]
 	if target not in runner.macro_table:
-		return CommandStatus(
+		printf(
-			formatted_text = HTML(
+			HTML(
-				f"<red>Macro \"{target}\" is not defined</red>"
+				f"<warn>Macro \"{target}\" is not defined</warn>"
-			)
+			),
+			style = utils.style
 		)
+		return
 
 	del runner.macro_table[target]
 
+
+
 @lamb_command(help_text = "Show macros")
-def macros(command, runner):
+def macros(command, runner) -> None:
-	return CommandStatus(
+	printf(FormattedText([
-		formatted_text = FormattedText([
+			("class:cmd_h", "\nDefined Macros:\n"),
-			("#FF6600 bold", "\nDefined Macros:\n"),
 		] +
 		[
-			("#FFFFFF", f"\t{name} \t {exp}\n")
+			("class:cmd_text", f"\t{name} \t {exp}\n")
 			for name, exp in runner.macro_table.items()
-		]
+		]),
-		)
+		style = utils.style
 	)
 
 @lamb_command(help_text = "Clear the screen")
-def clear(command, runner):
+def clear(command, runner) -> None:
 	clear_screen()
 	utils.show_greeting()
 
 
 @lamb_command(help_text = "Print this help")
-def help(command, runner):
+def help(command, runner) -> None:
-	return CommandStatus(
+	printf(
-		formatted_text = FormattedText([
+		HTML(
-			("#FF6600 bold", "\nUsage:\n"),
+			"\n<cmd_text>" +
-			(
+			"<cmd_h>Usage:</cmd_h>" +
-				"#FFFFFF",
+			"\n" +
-				"\tWrite lambda expressions using your "
+			"\tWrite lambda expressions using your <cmd_key>\\</cmd_key> key." +
-			),
+			"\n" +
-			(
+			"\tMacros can be defined using <cmd_key>=</cmd_key>, as in <cmd_code>T = λab.a</cmd_code>" +
-				"#00FF00",
+			"\n" +
-				"\\"
+			"\tRun commands using <cmd_key>:</cmd_key>, for example <cmd_code>:help</cmd_code>" +
-			),
+			"\n\n" +
-			(
+			"<cmd_h>Commands:</cmd_h>"+
-				"#FFFFFF",
+			"\n" +
-				" key.\n" +
+			"\n".join([
-				"\tMacros can be defined using "
+				f"\t{name} \t {text}"
-			),
-
-
-			("#00FF00", "="),
-			(
-				"#FFFFFF",
-				", as in "
-			),
-			(
-				"#AAAAAA bold",
-				"T = λab.a\n"
-			),
-
-
-			(
-				"#FFFFFF",
-				"\tRun commands using "
-			),
-			(
-				"#00FF00",
-				":"
-			),
-			(
-				"#FFFFFF",
-				", for example "
-			),
-			(
-				"#AAAAAA bold",
-				":help"
-			),
-
-			("#FF6600 bold", "\n\nCommands:\n")
-		] +
-		[
-			("#FFFFFF", f"\t{name} \t {text}\n")
 				for name, text in help_texts.items()
-		]
+			]) +
-		)
+			"</cmd_text>"
+		),
+		style = utils.style
 	)

lamb/parser.py

@@ -1,5 +1,8 @@
 import pyparsing as pp
 
+# Packrat gives a MAD speed boost.
+pp.ParserElement.enablePackrat()
+
 import lamb.tokens as tokens
 import lamb.utils as utils
 

lamb/runner.py

@@ -1,5 +1,4 @@
-from distutils.cmd import Command
+from prompt_toolkit import PromptSession
-from prompt_toolkit.formatted_text import FormattedText
 
 import lamb.commands as commands
 from lamb.parser import Parser
@@ -7,26 +6,18 @@ import lamb.tokens as tokens
 import lamb.runstatus as rs
 
 
-
 class Runner:
-	def __init__(self):
+	def __init__(self, prompt_session: PromptSession, prompt_message):
 		self.macro_table = {}
+		self.prompt_session = prompt_session
+		self.prompt_message = prompt_message
 
 		# Maximum amount of reductions.
 		# If None, no maximum is enforced.
 		self.reduction_limit: int | None = 300
 
-	def exec_command(self, command: tokens.command) -> rs.CommandStatus:
+	def prompt(self):
-		if command.name in commands.commands:
+		return self.prompt_session.prompt(message = self.prompt_message)
-			return commands.run(command, self)
-
-		# Handle unknown commands
-		else:
-			return rs.CommandStatus(
-				formatted_text = FormattedText([
-					("#FFFF00", f"Unknown command \"{command}\"")
-				])
-			)
 
 
 	def reduce_expression(self, expr: tokens.LambdaToken) -> rs.ReduceStatus:
@@ -63,7 +54,7 @@ class Runner:
 
 
 	# Apply a list of definitions
-	def run(self, line: str) -> rs.RunStatus:
+	def run(self, line: str, *, macro_only = False) -> rs.RunStatus:
 		e = Parser.parse_line(line)
 
 		# If this line is a macro definition, save the macro.
@@ -79,14 +70,20 @@ class Runner:
 				macro_expr = e.exp
 			)
 
+		elif macro_only:
+			raise rs.NotAMacro()
+
 		# If this line is a command, do the command.
 		elif isinstance(e, tokens.command):
-			return self.exec_command(e)
+			commands.run(e, self)
+			return rs.CommandStatus(cmd = e.name)
 
 		# If this line is a plain expression, reduce it.
 		elif isinstance(e, tokens.LambdaToken):
 			e.bind_variables()
 			return self.reduce_expression(e)
+
+		# We shouldn't ever get here.
 		else:
 			raise TypeError(f"I don't know what to do with a {type(e)}")
 

lamb/runstatus.py

@@ -1,8 +1,19 @@
 from prompt_toolkit.formatted_text import FormattedText
+from prompt_toolkit.formatted_text import HTML
 import enum
 
 import lamb.tokens as tokens
 
+
+class NotAMacro(Exception):
+	"""
+	Raised when we try to run a non-macro line
+	while enforcing macro_only in Runner.run().
+
+	This should be caught and elegantly presented to the user.
+	"""
+	pass
+
 class RunStatus:
 	"""
 	Base class for run status.
@@ -33,10 +44,10 @@ class MacroStatus(RunStatus):
 
 
 class StopReason(enum.Enum):
-	BETA_NORMAL		= ("#FFFFFF", "β-normal form")
+	BETA_NORMAL		= ("class:text", "β-normal form")
-	LOOP_DETECTED	= ("#FFFF00", "loop detected")
+	LOOP_DETECTED	= ("class:warn", "loop detected")
-	MAX_EXCEEDED	= ("#FFFF00", "too many reductions")
+	MAX_EXCEEDED	= ("class:err", "too many reductions")
-	INTERRUPT		= ("#FF0000", "user interrupt")
+	INTERRUPT		= ("class:warn", "user interrupt")
 
 
 class ReduceStatus(RunStatus):
@@ -63,14 +74,11 @@ class ReduceStatus(RunStatus):
 class CommandStatus(RunStatus):
 	"""
 	Returned when a command is executed.
+	Doesn't do anything interesting.
 
 	Values:
-	`formatted_text`: What to print after this command is executed
+	`cmd`: The command that was run, without a colon.
 	"""
 
-	def __init__(
+	def __init__(self, *, cmd: str):
-		self,
+		self.cmd = cmd
-		*,
-		formatted_text: FormattedText
-	):
-		self.formatted_text = formatted_text

lamb/utils.py

@@ -30,6 +30,39 @@ def autochurch(results):
 	)
 
 
+style = Style.from_dict({
+	# Basic formatting
+	"text": "#FFFFFF",
+	"warn": "#FFFF00",
+	"err": "#FF0000",
+	"prompt": "#00FFFF",
+	"ok": "#B4EC85",
+
+	# Syntax
+	"syn_macro": "#FF00FF",
+	"syn_lambda": "#FF00FF",
+	"syn_bound": "#FF00FF",
+
+	# Titles for reduction results
+	"result_header": "#B4EC85 bold",
+
+	# Command formatting
+	# cmd_h:    section titles
+	# cmd_code: example snippets
+	# cmd_text: regular text
+	# cmd_key:  keyboard keys, usually one character
+	"cmd_h": "#FF6600 bold",
+	"cmd_code": "#AAAAAA italic",
+	"cmd_text": "#FFFFFF",
+	"cmd_key": "#B4EC85 bold",
+
+	# Only used in greeting
+	"_v": "#B4EC85 bold",
+	"_l": "#FF6600 bold",
+	"_s": "#B4EC85 bold",
+	"_p": "#AAAAAA"
+})
+
 
 def show_greeting():
 	#   |  _.._ _.|_
@@ -62,19 +95,4 @@ def show_greeting():
 		"<_s> A λ calculus engine</_s>",
 		"<_p> Type :help for help</_p>",
 		""
-	])), style = Style.from_dict({
+	])), style = style)
-		# Heading
-		"_h": "#FFFFFF bold",
-
-		# Version
-		"_v": "#B4EC85 bold",
-
-		# Lambda
-		"_l": "#FF6600 bold",
-
-		# Subtitle
-		"_s": "#B4EC85 bold",
-
-		# :help message
-		"_p": "#AAAAAA"
-	}))