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LICENSE.txt

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+Written by Mark Kantrowitz, School of Computer Science,
+Carnegie Mellon University, March 1993.
+
+Copyright (c) 1993 by Mark Kantrowitz. All rights reserved.
+
+Use and copying of this software and preparation of derivative works
+based upon this software are permitted, so long as the following
+conditions are met:
+
+     * no fees or compensation are charged for use, copies, 
+       distribution or access to this software
+
+     * this copyright notice is included intact.
+
+This software is made available AS IS, and no warranty is made about
+the software or its performance.
+
+In no event will the author(s) or their institutions be liable to you
+for damages, including lost profits, lost monies, or other special,
+incidental or consequential damages, arising out of or in connection
+with the use or inability to use (including but not limited to loss of
+data or data being rendered inaccurate or losses sustained by third
+parties or a failure of the program to operate as documented) the
+program, or for any claim by any other party, whether in an action of
+contract, negligence, or other tortious action.

README.md

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+# CMU-INFIX
+
+A library for writing infix mathematical notation in Common Lisp.
+
+## Origin
+
+This library was originally written by Mark Kantrowitz in 1993 with updates the following few years. The code in this repository was derived from the original [`infix.cl`](https://www.cs.cmu.edu/Groups/AI/lang/lisp/code/syntax/infix/infix.cl) library provided by the CMU AI Repository. For posterity, a copy of this original file—otherwise unused by this library—can be found in [`attic/infix.cl`](attic/infix.cl).
+
+With minimal changes to the core functionality, the library was modernized by Robert Smith to be in-line with contemporary Common Lisp usage.
+
+## Example Use
+
+This package uses [`named-readtables`](https://common-lisp.net/project/named-readtables) to manage the readtables. If you've loaded `CMU-INFIX` successfully, then you'll have this package loaded as well.
+
+To use `CMU-INFIX`, simply use the readtable named `cmu-infix:syntax`:
+
+```lisp
+(named-readtables:in-readtable cmu-infix:syntax)
+```
+
+Once you have this, you can use the `#I` syntax for infix syntax. Here are some examples.
+
+**Example**: Pythagorean Theorem
+
+```lisp
+(defun hypot (a b)
+  "Compute the length of the hypotenuse of a right triangle
+   with sides A and B."
+  #I( sqrt(a^^2 + b^^2) ))
+```
+
+**Example**: Power-of-Two Check
+
+```lisp
+(defun power-of-two-p (n)
+  "Check if N is a power of 2."
+  #I( n != 0 and (n & (n - 1)) == 0 ))
+```
+
+
+
+**Example**: Euclidean Algorithm
+
+```lisp
+(defun euclid (a b)
+  "Compute the GCD of A and B using Euclid's algorithm."
+  (let (temp)
+    (loop :until #I( b == 0 ) :do
+      #I( temp := b,
+          b := a % b,
+          a := temp
+        ))
+    a))
+```
+
+**Example**: Matrix Multiplication
+
+```lisp
+(defun matmul (A B)
+  "Compute C = A * B for matrices A and B."
+  (let* ((m (array-dimension A 0))
+         (n (array-dimension A 1))
+         (q (array-dimension B 1))
+         (C (make-array (list m q) :initial-element 0)))
+    (loop :for i :below m :do
+      (loop :for k :below q :do
+        (loop :for j :below n :do
+          #I( C[i, k] += A[i, j] * B[j, k] ))))
+    C))
+
+;; Example:
+(let ((A (make-array '(2 2) :initial-contents '((0 1) (1 0))))
+      (B (make-array '(2 1) :initial-contents '((2) (3)))))
+  #I( matmul(A, B) ))
+```
+
+A full description of the supported operators is in the package documentation for `CMU-INFIX`:
+
+```lisp
+(format t "~A" (documentation (find-package :cmu-infix) t))
+```
+
+## Modernization Updates
+
+The library has been updated in the following ways:
+
+* The package of this library has been renamed `CMU-INFIX` so as to not conflict with existing Quicklisp libraries.
+
+* A system of the same name has been made so it is loadable by ASDF.
+
+* The tests have been lifted and put into a separate system called `CMU-INFIX-TESTS`. You can run them by doing
+
+  ```lisp
+  (asdf:test-system :cmu-infix)
+  ```
+
+* The library was modified to use `NAMED-READTABLES` to not eagerly pollute your readtable.
+
+* Some out-of-date comments have been deleted.
+
+## Contributing
+
+After receiving permission from Mark Kantrowitz, [Rigetti Computing](http://rigetti.com/) has taken stewardship of the library. Questions and issues should be filed on GitHub [here](https://github.com/rigetticomputing/cmu-infix), and pull requests are welcome. The licensing terms are described in [`LICENSE.txt`](LICENSE.txt).