Added a few commands

README.md

@@ -3,7 +3,7 @@
 
 ## Todo (pre-release):
  - Fix parser (call parentheses)
- - Good command parsing (`:help`, `:save`, `:load`, `:macros`, `:clear` are a bare minimum)
+ - Good command parsing (`:save`, `:load`, are a bare minimum)
  - Python files: installable, package list, etc
  - $\alpha$-equivalence check
  - Versioning
@@ -16,3 +16,4 @@
  - Maybe a better icon?
  - Warn when overwriting macro
  - Syntax highlighting: parenthesis, bound variables, macros, etc
+ - Pin header to top of screen

commands.py

@@ -0,0 +1,96 @@
+from prompt_toolkit.formatted_text import FormattedText
+from prompt_toolkit.shortcuts import clear as clear_screen
+
+from runstatus import CommandStatus
+import greeting
+
+
+
+commands = {}
+help_texts = {}
+
+def lamb_command(*, help_text: str):
+	def inner(func):
+		commands[func.__name__] = func
+		help_texts[func.__name__] = help_text
+	return inner
+
+def run(command, runner):
+	return commands[command](runner)
+
+
+@lamb_command(help_text = "Show macros")
+def macros(runner):
+	return CommandStatus(
+		formatted_text = FormattedText([
+			("#FF6600 bold", "\nDefined Macros:\n"),
+		] +
+		[
+			("#FFFFFF", f"\t{name} \t {exp}\n")
+			for name, exp in runner.macro_table.items()
+		]
+		)
+	)
+
+@lamb_command(help_text = "Clear the screen")
+def clear(runner):
+	clear_screen()
+	greeting.show()
+
+
+@lamb_command(help_text = "Print this help")
+def help(runner):
+	return CommandStatus(
+		formatted_text = FormattedText([
+			("#FF6600 bold", "\nUsage:\n"),
+			(
+				"#FFFFFF",
+				"\tWrite lambda expressions using your "
+			),
+			(
+				"#00FF00",
+				"\\"
+			),
+			(
+				"#FFFFFF",
+				" key.\n" +
+				"\tMacros can be defined using "
+			),
+
+
+			("#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()
+		]
+		)
+	)

greeting.py

@@ -1,6 +1,6 @@
 from prompt_toolkit.styles import Style
 from prompt_toolkit.formatted_text import HTML, to_formatted_text
-from prompt_toolkit import print_formatted_text
+from prompt_toolkit import print_formatted_text as printf
 
 
 
@@ -30,7 +30,10 @@ style = Style.from_dict({
 	"_l": "#FF6600 bold",
 
 	# Subtitle
-	"_s": "#B4EC85 bold"
+	"_s": "#B4EC85 bold",
+
+	# :help message
+	"_p": "#AAAAAA"
 })
 
 html = HTML(f"""
@@ -46,8 +49,9 @@ html = HTML(f"""
      `'._.--._.'
 
 <_s> A λ calculus engine</_s>
+<_p> Type :help for help</_p>
 
 """[1:-1])
 
 def show():
-	print_formatted_text(html, style = style)
+	printf(html, style = style)

main.py

@@ -86,6 +86,9 @@ while True:
 	if isinstance(x, runner.MacroStatus):
 		pass
 
+	if isinstance(x, runner.CommandStatus):
+		printf(x.formatted_text)
+
 	# If this line was an expression, print reduction status
 	elif isinstance(x, runner.ReduceStatus):
 		printf(FormattedText([

runner.py

@@ -1,60 +1,17 @@
+from prompt_toolkit.formatted_text import FormattedText
+
 import tokens
 from parser import Parser
-import enum
+import commands
+from runstatus import RunStatus
+from runstatus import MacroStatus
+from runstatus import StopReason
+from runstatus import ReduceStatus
+from runstatus import CommandStatus
 
 
-class RunStatus:
-	"""
-	Base class for run status.
-	These are returned whenever the runner does something.
-	"""
-	pass
-
-class MacroStatus(RunStatus):
-	"""
-	Returned when a macro is defined.
-
-	Values:
-	`was_rewritten`:	If true, an old macro was replaced.
-	`macro_label`:		The name of the macro we just made.
-	"""
-
-	def __init__(
-		self,
-		*,
-		was_rewritten: bool,
-		macro_label: str
-	):
-		self.was_rewritten = was_rewritten
-		self.macro_label = macro_label
 
 
-class StopReason(enum.Enum):
-	BETA_NORMAL		= ("#FFFFFF", "β-normal form")
-	LOOP_DETECTED	= ("#FFFF00", "loop detected")
-	MAX_EXCEEDED	= ("#FFFF00", "too many reductions")
-	INTERRUPT		= ("#FF0000", "user interrupt")
-
-
-class ReduceStatus(RunStatus):
-	"""
-	Returned when an expression is reduced.
-
-	Values:
-	`reduction_count`:	How many reductions were made.
-	`stop_reason`:		Why we stopped. See `StopReason`.
-	"""
-
-	def __init__(
-		self,
-		*,
-		reduction_count: int,
-		stop_reason: StopReason,
-		result: tokens.LambdaToken
-	):
-		self.reduction_count = reduction_count
-		self.stop_reason = stop_reason
-		self.result = result
 
 
 class Runner:
@@ -65,9 +22,18 @@ class Runner:
 		# If None, no maximum is enforced.
 		self.reduction_limit: int | None = 300
 
-	def exec_command(self, command: str):
+	def exec_command(self, command: str) -> CommandStatus:
-		if command == "help":
+		if command in commands.commands:
-			print("This is a help message.")
+			return commands.run(command, self)
+
+		# Handle unknown commands
+		else:
+			return CommandStatus(
+				formatted_text = FormattedText([
+					("#FFFF00", f"Unknown command \"{command}\"")
+				])
+			)
+
 
 	def reduce_expression(self, expr: tokens.LambdaToken) -> ReduceStatus:
 

runstatus.py

@@ -0,0 +1,73 @@
+import enum
+import tokens
+from prompt_toolkit.formatted_text import FormattedText
+
+
+class RunStatus:
+	"""
+	Base class for run status.
+	These are returned whenever the runner does something.
+	"""
+	pass
+
+class MacroStatus(RunStatus):
+	"""
+	Returned when a macro is defined.
+
+	Values:
+	`was_rewritten`:	If true, an old macro was replaced.
+	`macro_label`:		The name of the macro we just made.
+	"""
+
+	def __init__(
+		self,
+		*,
+		was_rewritten: bool,
+		macro_label: str
+	):
+		self.was_rewritten = was_rewritten
+		self.macro_label = macro_label
+
+
+class StopReason(enum.Enum):
+	BETA_NORMAL		= ("#FFFFFF", "β-normal form")
+	LOOP_DETECTED	= ("#FFFF00", "loop detected")
+	MAX_EXCEEDED	= ("#FFFF00", "too many reductions")
+	INTERRUPT		= ("#FF0000", "user interrupt")
+
+
+class ReduceStatus(RunStatus):
+	"""
+	Returned when an expression is reduced.
+
+	Values:
+	`reduction_count`:	How many reductions were made.
+	`stop_reason`:		Why we stopped. See `StopReason`.
+	"""
+
+	def __init__(
+		self,
+		*,
+		reduction_count: int,
+		stop_reason: StopReason,
+		result: tokens.LambdaToken
+	):
+		self.reduction_count = reduction_count
+		self.stop_reason = stop_reason
+		self.result = result
+
+
+class CommandStatus(RunStatus):
+	"""
+	Returned when a command is executed.
+
+	Values:
+	`formatted_text`: What to print after this command is executed
+	"""
+
+	def __init__(
+		self,
+		*,
+		formatted_text: FormattedText
+	):
+		self.formatted_text = formatted_text