File cleanup

README.md

@@ -19,6 +19,7 @@
 
 ## Usage
 
+
 Type lambda expressions into the prompt, and Lamb will evaluate them. \
 Use your `\` (backslash) key to type a `λ`. \
 To define macros, use `=`. For example,
@@ -30,22 +31,30 @@ To define macros, use `=`. For example,
 
 Note that there are spaces in `λa.a F T`. With no spaces, `aFT` will be parsed as one variable. \
 Lambda functions can only take single-letter, lowercase arguments. `λA.A` is not valid syntax. \
-Unbound variables (upper and lower case) that aren't macros will become free variables. Free variables will be shown with a `'`, like `a'`.
+Free variables will be shown with a `'`, like `a'`.
 
-Be careful, macros are case-sensitive. If you define a macro `MAC` and accidentally write `mac` in the prompt, `mac` will become a free variable.
+Macros are case-sensitive. If you define a macro `MAC` and accidentally write `mac` in the prompt, `mac` will become a free variable.
 
 Numbers will automatically be converted to Church numerals. For example, the following line will reduce to `T`.
 ```
 ==> 3 NOT F
 ```
 
-If an expression takes too long to evaluate, you may interrupt reduction with `Ctrl-C`.
+If an expression takes too long to evaluate, you may interrupt reduction with `Ctrl-C`. \
+Exit the prompt with `Ctrl-C` or `Ctrl-D`.
+
+There are many useful macros in [macros.lamb](./macros.lamb). Load them with the `:load` command:
+```
+==> :load macros.lamb
+```
+
+Have fun!
 
 -------------------------------------------------
 
 ## Commands
 
-Lamb comes with a few commands. Prefix them with a `:`
+Lamb understands many commands. Prefix them with a `:` in the prompt.
 
 `:help` Prints a help message
 
@@ -60,7 +69,9 @@ Lamb comes with a few commands. Prefix them with a `:`
 `:clearmacros` Delete all macros
 
 `:save [filename]` \
-`:load [filename]` Save or load the current environment to a file. The lines in a file look exactly the same as regular entries in the prompt, but must only contain macro definitions.
+`:load [filename]` \
+Save or load macros from a file.
+The lines in a file look exactly the same as regular entries in the prompt, but can only contain macro definitions. See [macros.lamb](./macros.lamb) for an example.
 
 -------------------------------------------------
 

lamb/__main__.py

@@ -1,66 +1,29 @@
+if __name__ != "__main__":
+	raise ImportError("lamb.__main__ should never be imported. Run it directly.")
+
 from prompt_toolkit import PromptSession
-from prompt_toolkit.completion import WordCompleter
 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
 
 import lamb
 
 
-# Simple lexer for highlighting.
-# Improve this later.
-class LambdaLexer(Lexer):
-	def lex_document(self, document):
-		def inner(line_no):
-			return [("class:text", str(document.lines[line_no]))]
-		return inner
-
-
 lamb.utils.show_greeting()
 
 
-# Replace "\" with pretty "λ"s
-bindings = KeyBindings()
-@bindings.add("\\")
-def _(event):
-	event.current_buffer.insert_text("λ")
-
-
 r = lamb.Runner(
 	prompt_session = PromptSession(
 		style = lamb.utils.style,
-		lexer = LambdaLexer(),
+		lexer = lamb.utils.LambdaLexer(),
-		key_bindings = bindings
+		key_bindings = lamb.utils.bindings
 	),
 	prompt_message = FormattedText([
 		("class:prompt", "==> ")
 	])
 )
 
-
-r.run_lines([
-	"T = λab.a",
-	"F = λab.b",
-	"NOT = λa.(a F T)",
-	"AND = λab.(a b F)",
-	"OR = λab.(a T b)",
-	"XOR = λab.(a (NOT b) b)",
-	"M = λx.(x x)",
-	"W = M M",
-	"Y = λf.( (λx.(f (x x))) (λx.(f (x x))) )",
-	"PAIR = λabi.( i a b )",
-	"S = λnfa.(f (n f a))",
-	"Z = λn.n (λa.F) T",
-	"MULT = λnmf.n (m f)",
-	"H = λp.((PAIR (p F)) (S (p F)))",
-	"D = λn.n H (PAIR 0 0) T",
-	"FAC = λyn.(Z n)(1)(MULT n (y (D n)))"
-])
-
-
 while True:
 	try:
 		i = r.prompt()

lamb/commands.py

@@ -101,7 +101,14 @@ def cmd_load(command, runner):
 		lines = [x.strip() for x in f.readlines()]
 
 	for i in range(len(lines)):
-		l = lines[i]
+		l = lines[i].strip()
+
+		# Skip comments and empty lines
+		if l.startswith("#"):
+			continue
+		if l == "":
+			continue
+
 		try:
 			x = runner.parse(l)[0]
 		except ppx.ParseException as e:

lamb/parser.py

@@ -56,7 +56,7 @@ class LambdaParser:
 			(self.lp + self.pp_history + self.rp)
 		)
 
-		self.pp_command = pp.Suppress(":") + pp.Word(pp.alphas + "_") + pp.Word(pp.alphas + pp.nums + "_")[0, ...]
+		self.pp_command = pp.Suppress(":") + pp.Word(pp.alphas + "_") + pp.Word(pp.alphas + pp.nums + "_.")[0, ...]
 
 
 		self.pp_all = (

lamb/utils.py

@@ -1,5 +1,7 @@
 from prompt_toolkit.styles import Style
 from prompt_toolkit.formatted_text import HTML
+from prompt_toolkit.lexers import Lexer
+from prompt_toolkit.key_binding import KeyBindings
 from prompt_toolkit import print_formatted_text as printf
 from importlib.metadata import version
 
@@ -14,6 +16,11 @@ style = Style.from_dict({ # type: ignore
 	"code": "#AAAAAA italic",
 	"muted": "#AAAAAA",
 
+	# Syntax highlighting colors
+	"syn_cmd": "#FFFFFF italic",
+	"syn_lambda": "#AAAAAA",
+	"syn_paren": "#AAAAAA",
+
 	# Command formatting
 	# cmd_h:    section titles
 	# cmd_key:  keyboard keys, usually one character
@@ -28,6 +35,46 @@ style = Style.from_dict({ # type: ignore
 })
 
 
+# Replace "\" with pretty "λ"s
+bindings = KeyBindings()
+@bindings.add("\\")
+def _(event):
+	event.current_buffer.insert_text("λ")
+
+# Simple lexer for highlighting.
+# Improve this later.
+class LambdaLexer(Lexer):
+	def lex_document(self, document):
+		def inner(line_no):
+			out = []
+			tmp_str = []
+			d = str(document.lines[line_no])
+
+			if d.startswith(":"):
+				return [
+					("class:syn_cmd", d)
+				]
+
+			for c in d:
+				if c in "\\λ.":
+					if len(tmp_str) != 0:
+						out.append(("class:text", "".join(tmp_str)))
+					out.append(("class:syn_lambda", c))
+					tmp_str = []
+				elif c in "()":
+					if len(tmp_str) != 0:
+						out.append(("class:text", "".join(tmp_str)))
+					out.append(("class:syn_paren", c))
+					tmp_str = []
+				else:
+					tmp_str.append(c)
+
+			if len(tmp_str) != 0:
+				out.append(("class:text", "".join(tmp_str)))
+			return out
+		return inner
+
+
 def show_greeting():
 	#   |  _.._ _.|_
 	#   |_(_|| | ||_)

macros.lamb

@@ -0,0 +1,77 @@
+# How to use exported files in lamb:
+#
+# [Syntax Highlighting]
+#	Most languages' syntax highlighters will
+#	highlight this code well. Set it manually
+#	in your editor.
+#
+#	Don't use a language for which you have a
+#	linter installed, you'll get lots of errors.
+#
+#	Choose a language you don't have extenstions for,
+#	and a language that uses # comments.
+#
+# The following worked well in vscode:
+# - Julia
+# - Perl
+# - Coffeescript
+# - R
+
+# [Writing macros]
+#	If you don't have a custom keyboard layout that can
+#	create λs, you may use backslashes instead.
+#	(As in `T = \ab.b`)
+#
+#	This file must only contain macro definitons. Commands will be ignored.
+#	Statements CANNOT be split among multiple lines.
+#	Comments CANNOT be on the same line as macro defintions.
+#	All leading whitespace is ignored.
+
+
+# Misc Combinators
+M = λx.(x x)
+W = (M M)
+Y = λf.((λx.(f (x x))) (λx.(f (x x))))
+
+
+# Booleans
+T = λab.a
+F = λab.b
+NOT = λa.(a F T)
+AND = λab.(a b F)
+OR = λab.(a T b)
+XOR = λab.((a (NOT b)) b)
+
+
+# Numbers
+# PAIR: prerequisite for H.
+#	Makes a two-value tuple, indexed with T and F.
+#
+# H: shift-and-add, prerequisite for D
+#
+# S: successor (adds 1)
+#
+# D: predecessor (subtracts 1)
+#
+# Z: tests if a number is zero
+# NZ: equivalent to `NOT Z`
+#
+# ADD: adds two numbers
+#
+# MULT: multiply two numbers
+#
+# FAC:
+#	Recursive factorial. Call with `Y FAC <number>`
+#	Don't call this with numbers bigger than 5 unless you're very patient.
+#
+#	`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)
+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))) )

pyproject.toml

@@ -14,7 +14,7 @@ description = "A lambda calculus engine"
 #
 # Patch release:
 # Small, compatible fixes.
-version = "0.1.2"
+version = "0.1.3"
 
 dependencies = [
 	"prompt-toolkit==3.0.31",