Create README.md

README.md

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+### Solving cryptarithmetic problems in Racket
+
+This is just a simple library to solve simple cryptarithmetic problems. 
+
+You just call a single function `solve`. 
+
+For example to solve this: 
+
+![SEND + MORE = MONEY](send.png)
+
+You'd just have to call the `solve` function like so:
+
+```racket 
+(solve '(S E N D)
+ '(M O R E)
+ '(M O N E Y))
+```
+
+This returns a (lazy) stream of solutions: 
+
+```racket
+#<stream>
+```
+
+Most *good* crytarithmetic problems usually have a single solution. 
+
+To get a solution just use the standard `racket/stream` functions: 
+
+
+```racket 
+(define s
+ (solve '(S E N D)
+ '(M O R E)
+ '(M O N E Y)))
+ 
+(stream-first s)
+```
+And sure enough, you'd get: 
+
+```racket 
+'((M . 1)
+ (N . 6)
+ (O . 0)
+ (Y . 2)
+ (D . 7)
+ (E . 5)
+ (R . 8)
+ (S . 9))
+```
+If a particular crytparithmetic problem doesn't have a solution and you 
+try to invoke `stream-first` on its stream you'd get an exception saying 
+you it expected a non-empty stream:
+
+```racket
+stream-first: contract violation
+ expected: (and/c stream? (not/c stream-empty?))
+ given: #<stream>
+```
+
+Note that it might take a while to get a solution because it searches
+for a solution and returns the first it finds and stops seraching.
+
+if 
+
+
+