README.md

@@ -1,95 +1,24 @@
 # Lamb: A Lambda Calculus Engine
 
-![Lamb screenshot](./misc/screenshot.png)
-
-## Installation
-
-### Method 1: PyPi (not yet)
-1. Put this on PyPi
-2. Write these instructions
-
-### Method 2: Git
-1. Clone this repository.
-2. Make and enter a [virtual environment](https://docs.python.org/3/library/venv.html).
-3. ``cd`` into this directory
-4. Run ``pip install .``
-5. Run ``python .``
-
--------------------------------------------------
-
-## 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,
-```
-~~> T = λab.a
-~~> F = λab.a
-~~> NOT = λa.a F T
-```
-
-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.
-
-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.
-
-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`.
-
--------------------------------------------------
-
-## Commands
-
-Lamb comes with a few commands. Prefix them with a `:`
-
-`:help` Prints a help message
-
-`:clear` Clear the screen
-
-`:rlimit [int | None]` Set maximum reduction limit. `:rlimit none` sets no limit.
-
-`:macros` List macros in the current environment.
-
-`:mdel [macro]` Delete a macro
-
-`: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.
-
--------------------------------------------------
-
-## Internals
-
-Lamb treats each λ expression as a binary tree. Variable binding and reduction are all simple operations on that tree. All the magic happens inside [`nodes.py`](./lamb/nodes.py).
-
-**Highlights:**
- - `TreeWalker` is the iterator we (usually) use to traverse our tree. It walks the "perimeter" of the tree, visiting some nodes multiple times.
- - `Node` is the base class for all nodes. Any node has `.left` and `.right` elements, which may be `None` (empty). `Node`s also reference their parent and their direction relative to their parent, to make tree traversal easy.
- - Before any reduction is done, variables are bound via `bind_variables`. This prevents accidental conflicts common in many lambda parsers.
-
--------------------------------------------------
-
 
 ## Todo (pre-release):
- - Make command output accessible in prompt
+ - $\alpha$-equivalence check
- - Prettyprint functions and rename bound variables
+ - Prettyprint functions (rename bound variables)
- - Prettier colors
+ - Write a nice README
- - Prevent macro-chaining recursion
+ - Fix colors
- - step-by-step reduction
+ - Print macro content if only a macro is typed
- - Show a warning when a free variable is created
- - PyPi package
-
 
 ## Todo:
- - Command-line options (load a file, run a set of commands)
+ - History accessible in prompt
- - $\alpha$-equivalence check
+ - Command and macro autocomplete
- - Unchurch macro: make church numerals human-readable
+ - step-by-step reduction
- - Full-reduce option (expand all macros)
- - Print macro content if only a macro is typed
- - Smart alignment in all printouts
  - Syntax highlighting: parenthesis, bound variables, macros, etc
+ - PyPi package
+ - Smart alignment in all printouts
+ - Full-reduce option
+ - Free variable warning
 
+## Mention in Docs
+ - lambda functions only work with single-letter arguments
+ - church numerals
+ - how to install

lamb/node.py

@@ -84,7 +84,6 @@ class TreeWalker:
 class Node:
 	"""
 	Generic class for an element of an expression tree.
-	All nodes are subclasses of this.
 	"""
 
 	def __init__(self):
@@ -452,6 +451,8 @@ def bind_variables(node: Node, *, ban_macro_name = None) -> None:
 
 		# If this expression is part of a macro,
 		# make sure we don't reference it inside itself.
+		#
+		# TODO: A chain of macros could be used to work around this. Fix that!
 		if isinstance(n, Macro) and ban_macro_name is not None:
 			if n.name == ban_macro_name:
 				raise ReductionError("Macro cannot reference self")

pyproject.toml

@@ -1,21 +1,7 @@
 [project]
 name = "Lamb"
 description = "A lambda calculus engine"
-
+version = "0.0.0"
-# We use the standard semantic versioning:
-# maj.min.pat
-#
-# Major release:
-# 1.0.0 is the first stable release.
-# Incremented on BIG breaking changes.
-#
-# Minor release:
-# Large bug fixes, new features
-#
-# Patch release:
-# Small, compatible fixes.
-version = "0.1.0"
-
 dependencies = [
 	"prompt-toolkit==3.0.31",
 	"pyparsing==3.0.9"