first commit, delete original .git and reinitialize

.gitattributes

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+# Auto detect text files and perform LF normalization
+* text=auto
+
+# Custom for Visual Studio
+*.cs     diff=csharp
+
+# Standard to msysgit
+*.doc	 diff=astextplain
+*.DOC	 diff=astextplain
+*.docx diff=astextplain
+*.DOCX diff=astextplain
+*.dot  diff=astextplain
+*.DOT  diff=astextplain
+*.pdf  diff=astextplain
+*.PDF	 diff=astextplain
+*.rtf	 diff=astextplain
+*.RTF	 diff=astextplain

SchemerNums.rkt

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+#lang racket
+;string functions
+(define firsts
+  (lambda (l)
+    (cond
+      [(null? l)(quote())]
+      [else (cons (car (car l))
+                  (firsts (cdr l)))])))
+
+(define atom?
+(lambda (x)
+(and (not (pair? x)) (not (null? x)))))
+;lat returns true if l is a list of atoms
+(define lat?
+  (lambda (l)
+  (cond
+    [(null? l) #t]
+    [(atom? (car l)) (lat? (cdr l))]
+    [else #f]
+    )))
+;number functions
+(define add1
+  (lambda (n)
+    (+ n 1)))
+
+(define sub1
+  (lambda (n)
+    (- n 1)))
+
+(define add
+  (lambda (n m)
+    (cond
+      [(zero? m) n]
+      [else (add1 (add n (sub1 m)))]
+      )))
+
+(define subt
+  (lambda (n m)
+    (cond
+      [(zero? m) n]
+      [else (sub1 (subt n (sub1 m)))]
+      )))
+
+(define multi
+  (lambda (n m)
+    (cond
+      [(zero? m) 0]
+      [else (+ n (multi n (sub1 m)))]
+      )))
+
+(define divi
+  (lambda (n m)
+    (cond
+      [(zero? m) 0]
+      [(< (subt n m) 0) 0]
+      [(<= n 0) 0]
+      [else (add1 (div (subt n m) m))])))
+
+
+
+(define length
+  (lambda (lat)
+    (cond
+      [(null? lat) 0]
+      [else (add1(length(cdr lat)))])))
+
+(define pick
+    (lambda (n lat)
+      (cond
+        [(zero? (sub1 n))(car lat)]
+        [else (pick (sub1 n)(cdr lat))])))
+
+(define tup+
+  (lambda (tup1 tup2)
+    (cond
+      [(and(null? tup1)(null? tup2)) (quote ())]
+      [(null? tup1) tup2]
+      [(null? tup2) tup1]
+      [else (cons (add (car tup1)(car tup2))(tup+ (cdr tup1) (cdr tup2)))])))
+(define t1 (list 10 20 30 50 60 70))
+(define t2 (list 3 4 5 6))
+(define t3 (list 100 200 300))
+;tests
+;(tup+ t1 t3)
+;(tup+ t2 t3)
+;(tup+ t2 t1)
+(define grtr
+  (lambda (n m)
+    (cond
+      [(zero? n) #f]
+      [(zero? m) #t]
+      [else (grtr(sub1 n)(sub1 m))])))
+;(grtr 4 6)
+;(grtr 3 1)
+;(grtr 1 1)
+
+(define less
+  (lambda (n m)
+    (cond
+      [(zero? m) #f]
+      [(zero? n) #t]
+      [else (less(sub1 n)(sub1 m))])))
+;(less 4 6)
+;(less 3 1)
+;(less 1 1)
+(define eq?
+  (lambda (n m)
+    (cond
+    [(and(zero? n)(zero? m))]
+    [(or(zero? n)(zero? m)) #f]
+    [else (eq? (sub1 n)(sub1 m))])))
+;(eq? 1 3)
+;(eq? 3 1)
+;(eq? 0 1)
+;(eq? 1 1)
+;(eq? 0 0)
+
+(define div
+  (lambda (n m)
+    (cond
+      [(eq? m 0) "Err:div by 0"]
+      [(less n m) 0]
+      [(add1 (div (subt n m) m))])))
+    (div 45 9)
+(div 45 5)
+(div 45 1)
+(div 45 0)

SchemerStringOps.rkt

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+#lang racket
+
+(define atom?
+  (lambda (l)
+    (cond [(or (null? l)(pair? l)) #f]
+          [else #t])))
+
+
+(define lat?
+  (lambda (l)
+    (cond
+      [(null? l) #t]
+      [(atom? (car l)) (lat? (cdr l))]
+      [else #f]
+      )))
+(define multiSubst
+  (lambda (lat old new)
+    (cond
+      [(null? lat) (quote())]
+      [(eq?(car lat) old)
+       (cons new (multiSubst(cdr lat)))]
+      [else cons (car lat)
+            (multiSubst (cdr lat))]
+      )))
+

guess.rkt

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+;; The first three lines of this file were inserted by DrRacket. They record metadata
+;; about the language level of this file in a form that our tools can easily process.
+#reader(lib "htdp-beginner-reader.ss" "lang")((modname guess) (read-case-sensitive #t) (teachpacks ((lib "guess-gui.rkt" "teachpack" "htdp") (lib "guess.rkt" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "guess-gui.rkt" "teachpack" "htdp") (lib "guess.rkt" "teachpack" "htdp")) #f)))
+(define(check-guess guess target)
+  (cond [(> guess target) 'too_large]
+        [(<  guess target) 'too_small]
+        [else 'correct]
+        )
+  )
+
+(guess-with-gui check-guess)

quadratic.rkt

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+;; The first three lines of this file were inserted by DrRacket. They record metadata
+;; about the language level of this file in a form that our tools can easily process.
+#reader(lib "htdp-beginner-reader.ss" "lang")((modname quadratic) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f () #f)))
+(define(how-many a b c)
+  (cond[(= 0 a) "degenerate"]
+       [(>(* b b)(* 4 a c)) 2]
+       [(=(* b b)(* 4 a c)) 1]
+       [(<(* b b)(* 4 a c)) 0]
+       )
+  )
+(define(how-many2 a b c)
+  (cond[(= 0 a) "degenerate"]
+       [(>(discriminant a b c)0) 2]
+       [(=(discriminant a b c)0) 1]
+       [(<(discriminant a b c)0) 0]
+       )
+  )
+(define(discriminant a b c)
+  (-(* b b)(* 4 a c)))