From d5aff2cf4a760f8135c050c66af16f34f696bea5 Mon Sep 17 00:00:00 2001
From: David Florness <david@florness.com>
Date: Sat, 22 Feb 2020 20:49:23 -0700
Subject: [PATCH] Allow votes to be negative

---
 client.rkt | 40 ++++++++++++++++++++--------------------
 poly.rkt   | 15 +++++++--------
 2 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/client.rkt b/client.rkt
index 4d1dfb2..e86bc5d 100644
--- a/client.rkt
+++ b/client.rkt
@@ -10,8 +10,8 @@
 (require typed/json)
 (require/typed binaryio
   [bytes->integer (->* (Bytes Boolean) (Boolean Natural Natural) Integer)]
-  [integer->bytes (->* (Integer Natural Boolean) (Boolean Bytes Natural) Bytes)]
-  [integer-bytes-length (Integer Boolean -> Natural)])
+  [integer->bytes (->* (Integer Positive-Integer Boolean) (Boolean Bytes Natural) Bytes)]
+  [integer-bytes-length (-> Integer Boolean Natural)])
 (require/typed readline/readline
   [readline (-> String String)])
 (require/typed simple-http
@@ -35,12 +35,12 @@
   [crypto-random-bytes (Natural -> Bytes)])
 (require "poly.rkt")
 
-(define (natural->hex-string [n : Natural])
+(define (integer->hex-string [n : Integer])
   (bytes->hex-string
-   (integer->bytes n (integer-bytes-length n #f) #f)))
+   (integer->bytes n (assert (integer-bytes-length n #t) positive?) #t)))
 
-(define (hex-string->natural [hs : String])
-  (cast (bytes->integer (hex-string->bytes hs) #f #t) Natural))
+(define (hex-string->integer [hs : String])
+  (bytes->integer (hex-string->bytes hs) #t))
 
 (module+ main
   (define username (readline "Your name: "))
@@ -54,13 +54,13 @@
   (void
    (post bulletin "/register"
          #:data
-         (jsexpr->string (hasheq 'input (natural->hex-string point)
+         (jsexpr->string (hasheq 'input (integer->hex-string point)
                                  'name username))))
 
   (display "retrieving peers...")
   (define peer-inputs
     (map
-     hex-string->natural
+     hex-string->integer
      (cast
       (json-response-body
        (let loop ([wait 0])
@@ -79,13 +79,13 @@
   (define candidates (json-response-body (get bulletin "/candidates")))
 
   (define vote
-    (let loop : Natural ()
+    (let loop : Integer ()
       (let [(n (string->number (readline "Vote: ")))]
         (if (eq? n #f)
             (begin
               (displayln "Please enter a valid number")
               (loop))
-            (assert n natural?)))))
+            (assert n exact-integer?)))))
 
   (define poly (random-poly
                 (cast (sub1 (length peer-inputs)) Natural)
@@ -97,9 +97,9 @@
          #:data
          (jsexpr->string
           (for/hasheq : (Immutable-HashTable Symbol String)
-              ([p : Natural (cast peer-inputs (Listof Natural))])
-            (values (string->symbol (natural->hex-string p))
-                    (natural->hex-string (poly p)))))))
+              ([p : Integer (cast peer-inputs (Listof Integer))])
+            (values (string->symbol (integer->hex-string p))
+                    (integer->hex-string (poly p)))))))
 
   (display "summing...")
   (void
@@ -108,12 +108,12 @@
          (jsexpr->string
           (hasheq
            'input
-           (natural->hex-string point)
+           (integer->hex-string point)
            'sum
-           (natural->hex-string
+           (integer->hex-string
             (foldl + 0
                    (map
-                    hex-string->natural
+                    hex-string->integer
                     (cast
                      (json-response-body
                       (let loop ([wait 0])
@@ -128,14 +128,14 @@
                                 #:data
                                 (jsexpr->string
                                  (hasheq 'input
-                                         (natural->hex-string point)))))))
+                                         (integer->hex-string point)))))))
                      (Listof String)))))))))
   (newline)
 
   (display "finding constant...")
   (define constant
     (let ([k (length peer-inputs)]
-          [sums (for/hash : (Immutable-HashTable Natural Natural)
+          [sums (for/hash : (Immutable-HashTable Integer Integer)
                     ([(k v)
                       (in-hash
                        (cast
@@ -150,8 +150,8 @@
                                               (loop 3))])
                              (get bulletin "/sums"))))
                         (Immutable-HashTable Symbol String)))])
-                  (values (hex-string->natural (symbol->string k))
-                          (hex-string->natural v)))])
+                  (values (hex-string->integer (symbol->string k))
+                          (hex-string->integer v)))])
       (matrix-ref
        (matrix-solve
         ; M
diff --git a/poly.rkt b/poly.rkt
index 251498f..943f3c4 100644
--- a/poly.rkt
+++ b/poly.rkt
@@ -6,20 +6,19 @@
 (require/typed crypto
   [crypto-random-bytes (Natural -> Bytes)])
 
-(define-type Poly (Natural -> Natural))
-
-(define num-bytes (assert (/ 1024 8) natural?))
+(define-type Poly (Integer -> Integer))
 
 (define (gen)
-  (let* ([bstr (crypto-random-bytes num-bytes)])
-    (cast (bytes->integer bstr #f #t 0 num-bytes) Natural)))
+  (let* ([num-bytes (assert (/ 1024 8) natural?)]
+         [bstr (crypto-random-bytes num-bytes)])
+    (bytes->integer bstr #t #t 0 num-bytes)))
 
-(define (random-poly [degree : Natural] [constant : Natural]) : Poly
+(define (random-poly [degree : Natural] [constant : Integer]) : Poly
   (let ([coefficients (build-vector degree (λ (_) (gen)))])
-    (λ ([x : Natural]) : Natural
+    (λ ([x : Integer]) : Integer
        (cast (+ constant
                 (for/sum : Integer ([i degree])
                   (* (expt x (add1 i)) (vector-ref coefficients i))))
-             Natural))))
+             Integer))))
 
 (provide (all-defined-out))
-- 
2.38.4