Updated README

README.md

@@ -1,24 +1,95 @@
 # 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):
- - $\alpha$-equivalence check
+ - Make command output accessible in prompt
- - Prettyprint functions (rename bound variables)
+ - Prettyprint functions and rename bound variables
- - Write a nice README
+ - Prettier colors
- - Fix colors
+ - Prevent macro-chaining recursion
- - Print macro content if only a macro is typed
+ - step-by-step reduction
+ - Show a warning when a free variable is created
+ - PyPi package
+
 
 ## Todo:
- - History accessible in prompt
+ - Command-line options (load a file, run a set of commands)
- - Command and macro autocomplete
+ - $\alpha$-equivalence check
- - step-by-step reduction
+ - Unchurch macro: make church numerals human-readable
- - Syntax highlighting: parenthesis, bound variables, macros, etc
+ - Full-reduce option (expand all macros)
- - PyPi package
+ - Print macro content if only a macro is typed
  - Smart alignment in all printouts
- - Full-reduce option
+ - Syntax highlighting: parenthesis, bound variables, macros, etc
- - Free variable warning
 
-## Mention in Docs
- - lambda functions only work with single-letter arguments
- - church numerals
- - how to install

pyproject.toml

@@ -1,7 +1,21 @@
 [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"