Updated README

README.md

@@ -77,8 +77,7 @@ The lines in a file look exactly the same as regular entries in the prompt, but
 
 
 ## Todo (pre-release, in this order):
- - Cleanup warnings
- - Truncate long expressions in warnings
+ - Fix unique bound variable printer
  - Prevent macro-chaining recursion
  - Full-reduce option (expand all macros)
  - step-by-step reduction
@@ -89,12 +88,16 @@ The lines in a file look exactly the same as regular entries in the prompt, but
 
 
 ## Todo:
+ - Cleanup warnings
+ - Syntax highlight printouts
+ - Truncate long expressions in warnings
  - History queue + indexing
  - Show history command
  - Loop detection
+ - Optimization: reduction can be slow with large trees.
  - $\alpha$-equivalence check
  - Command-line options (load a file)
  - Unchurch command: make church numerals human-readable
  - Better Syntax highlighting
- - Syntax highlight printouts
+ - Complete file names and commands
  - Tests

lamb/nodes/functions.py

@@ -95,7 +95,7 @@ def clone(node: lbn.Node):
 			break
 	return out
 
-def prepare(root: lbn.Root, *, ban_macro_name = None) -> dict:
+def prepare(root: lbn.Root, *, ban_macro_name = None) -> list:
 	"""
 	Prepare an expression for expansion.
 	This will does the following:
@@ -109,15 +109,19 @@ def prepare(root: lbn.Root, *, ban_macro_name = None) -> dict:
 
 	bound_variables = {}
 
-	output = {
-		"has_history": False,
-		"free_variables": set()
-	}
+	warnings = []
 
 	it = iter(root)
 	for s, n in it:
 		if isinstance(n, lbn.History):
-			output["has_history"] = True
+			if len(root.runner.history) == 0:
+				raise lbn.ReductionError("There isn't any history to reference.")
+			else:
+				warnings += [
+					("class:code", "$"),
+					("class:warn", " will be expanded to "),
+					("class:code", f"{n.expand()[1]}\n"),
+				]
 
 		# If this expression is part of a macro,
 		# make sure we don't reference it inside itself.
@@ -135,7 +139,11 @@ def prepare(root: lbn.Root, *, ban_macro_name = None) -> dict:
 
 			# Turn undefined macros into free variables
 			elif n.name not in root.runner.macro_table:
-				output["free_variables"].add(n.name)
+				warnings += [
+					("class:warn", "Name "),
+					("class:code", n.name),
+					("class:warn", " is a free variable\n"),
+				]
 				n.parent.set_side(
 					n.parent_side,
 					n.to_freevar()
@@ -158,7 +166,7 @@ def prepare(root: lbn.Root, *, ban_macro_name = None) -> dict:
 			elif s == lbn.Direction.LEFT:
 				del bound_variables[n.input.name]
 
-	return output
+	return warnings
 
 # Apply a function.
 # Returns the function's output.

lamb/nodes/nodes.py

@@ -319,8 +319,10 @@ class History(ExpandableEndNode):
 		return "$"
 
 	def expand(self) -> tuple[lbn.ReductionType, Node]:
+		# We shouldn't ever get here, prepare()
+		# catches empty history.
 		if len(self.runner.history) == 0:
-			raise lbn.ReductionError(f"There isn't any history to reference.")
+			raise Exception(f"Tried to expand empty history.")
 		# .left is VERY important!
 		# self.runner.history will contain Root nodes,
 		# and we don't want those *inside* our tree.

lamb/runner/runner.py

@@ -56,25 +56,23 @@ class Runner:
 			message = self.prompt_message
 		)
 
-	def parse(self, line) -> tuple[lamb.nodes.Root | MacroDef | Command, dict]:
+	def parse(self, line) -> tuple[lamb.nodes.Root | MacroDef | Command, list]:
 		e = self.parser.parse_line(line)
 
-		o = {}
+		w = []
 		if isinstance(e, MacroDef):
 			e.expr = lamb.nodes.Root(e.expr)
 			e.set_runner(self)
-			o = lamb.nodes.prepare(e.expr, ban_macro_name = e.label)
+			w = lamb.nodes.prepare(e.expr, ban_macro_name = e.label)
 		elif isinstance(e, lamb.nodes.Node):
 			e = lamb.nodes.Root(e)
 			e.set_runner(self)
-			o = lamb.nodes.prepare(e)
+			w = lamb.nodes.prepare(e)
 
-		return e, o
+		return e, w
 
 
-	def reduce(self, node: lamb.nodes.Root, *, status = {}) -> None:
-
-		warning_text = []
+	def reduce(self, node: lamb.nodes.Root, *, warnings = []) -> None:
 
 		# Reduction Counter.
 		# We also count macro (and church) expansions,
@@ -86,14 +84,6 @@ class Runner:
 		start_time = time.time()
 		out_text = []
 
-		if status["has_history"] and len(self.history) != 0:
-			warning_text += [
-				("class:code", "$"),
-				("class:warn", " will be expanded to "),
-				("class:code", str(self.history[-1])),
-				("class:warn", "\n")
-			]
-
 		only_macro = (
 			isinstance(node.left, lamb.nodes.Macro) or
 			isinstance(node.left, lamb.nodes.Church)
@@ -103,16 +93,8 @@ class Runner:
 		m, node = lamb.nodes.expand(node, force_all = only_macro)
 		macro_expansions += m
 
-
-		for i in status["free_variables"]:
-			warning_text += [
-				("class:warn", "Name "),
-				("class:code", i),
-				("class:warn", " is a free variable\n"),
-			]
-
-		if len(warning_text) != 0:
-			printf(FormattedText(warning_text), style = lamb.utils.style)
+		if len(warnings) != 0:
+			printf(FormattedText(warnings), style = lamb.utils.style)
 
 
 		while (
@@ -210,7 +192,7 @@ class Runner:
 			*,
 			silent = False
 		) -> None:
-		e, o = self.parse(line)
+		e, w = self.parse(line)
 
 		# If this line is a macro definition, save the macro.
 		if isinstance(e, MacroDef):
@@ -230,7 +212,7 @@ class Runner:
 
 		# If this line is a plain expression, reduce it.
 		elif isinstance(e, lamb.nodes.Node):
-			self.reduce(e, status = o)
+			self.reduce(e, warnings = w)
 
 		# We shouldn't ever get here.
 		else:

macros.lamb

@@ -67,11 +67,11 @@ XOR = λab.((a (NOT b)) b)
 #	`Y FAC 6` required 867,920 reductions and took 10 minutes to run.
 
 PAIR = λabi.(i a b)
-H = λp.((PAIR (p F)) (S (p F)))
 S = λnfa.(f (n f a))
-D = λn.((n H) ((PAIR 0) 0) T)
+H = λp.((PAIR (p F)) (S (p F)))
+D = λn.(n H (PAIR 0 0) T)
 Z = λn.(n (λa.F) T)
 NZ = λn.(n (λa.T) F)
 ADD = λmn.(m S n)
 MULT = λnmf.(n (m f))
-FAC = λyn.( (Z n)(1)((MULT n) (y (D n))) )
+FAC = λyn.(Z n) (1) (MULT n (y (D n)))