Finished exercises in section 1.1 in Elixir

1.1-TheElementsOfProgramming/ex-1.1/icarosun.ex

@@ -0,0 +1,74 @@
+# lang elixir
+
+# Elixir use Infix notation 
+
+10
+# 10
+
+5 + 3 + 4
+# 12
+
+9 - 1
+# 8
+
+6 / 2
+# 3.0
+
+2 * 4 + 4 - 6
+# 6
+
+a = 3
+# 3
+
+b = a + 1
+# 4
+
+a + b + a * b
+# 19
+
+^a = b
+# match(error)
+
+a = b
+# 4
+
+if b > a and b < a * b do
+  b
+else
+  a
+end
+
+# 4
+
+cond do
+  a = 4 -> 6
+  b = 4 -> 6 + 7 + a
+  true -> 25
+end
+
+# warning(6)
+
+cond do
+  4 = a -> 6
+  4 = b -> 6 + 7 + a
+  true -> 25
+end
+
+# match(error)
+
+2 +
+  if b > a do
+    b
+  else
+    a
+  end
+
+# 6
+
+cond do
+  a > b -> a
+  a < b -> b
+  true -> -1
+end * (a + 1)
+
+# 16

1.1-TheElementsOfProgramming/ex-1.2/icarosun.ex

@@ -0,0 +1,7 @@
+#it not run in elixir
+(/ (+ 5 4 (- 2 (- 3 (+ 6 (/ 4 5)))))
+    (* 3 (- 6 2) (- 2 7)))
+
+#Infix notation
+#(5 + 4 + (2 - (3 - (6 + (4 / 5))))) / (3 * (6 - 2) * (2 - 7))
+

1.1-TheElementsOfProgramming/ex-1.3/icarosun.ex

@@ -0,0 +1,12 @@
+square = fn x -> x * x end
+
+sum_square = fn x, y -> square.(x) + square.(y) end
+
+procedure = fn x, y, z ->
+  cond do
+    x > y and z > y -> sum_square.(x, z)
+    true -> sum_square.(y, max(x, z))
+  end
+end
+
+# IO.puts(procedure.(3, 1, 5))

1.1-TheElementsOfProgramming/ex-1.4/icarosun.ex

@@ -0,0 +1,15 @@
+# It not run in elixir
+
+# (define (a-plus-abs-b a b)
+#  ((if (> b 0) + -) a b))
+
+a_plus_abs_b = fn
+  a, b when b > 0 -> a + b
+  a, b -> a - b
+end
+
+# IO.puts(a_plus_abs_b.(10, 1))
+#
+# The application will check if b is positive or negative. If b is negative, it will perform the
+# subtraction operation; otherwise, it will perform the addition operation. Therefore, b will always
+# be treated as an absolute value

1.1-TheElementsOfProgramming/ex-1.5/icarosun.ex

@@ -0,0 +1,38 @@
+# it no run in elixir
+
+# (define (p) (p))
+# (define (test x y)
+#  (if (= x 0) 0 y))
+
+defmodule Exercise do
+  def p() do
+    p()
+  end
+
+  def test(x, y) do
+    if x == 0 do
+      0
+    else
+      y
+    end
+  end
+end
+
+IO.puts(Exercise.test(0, Exercise.p()))
+
+# The code will enter a loop
+#
+# In applicative-order evaluation the code will enter a loop.
+# Applicative-order evaluation checks the argument first, then the the function
+#
+# (test 0 (p))
+# (test 0 (p)p)p)...)
+#
+# In normal-order evaluation, the code will run and finish by printing a zero.
+# Normal-order evaluation first check the function before the arguments the arguments
+#
+# (test 0 (p))
+# (if (= x 0) 0 (p))
+# (if (true) 0 (p))
+# 0
+#

1.1-TheElementsOfProgramming/ex-1.6/icarosun.ex

@@ -0,0 +1,46 @@
+average = fn x, y ->
+  (x + y) / 2
+end
+
+improve = fn guess, x ->
+  average.(guess, x / guess)
+end
+
+square = fn x -> x * x end
+
+good_enough? = fn guess, x ->
+  abs(square.(guess) - x) < 0.001
+end
+
+sqrt_iter = fn function, guess, x ->
+  if good_enough?.(guess, x) do
+    guess
+  else
+    function.(function, improve.(guess, x), x)
+  end
+end
+
+sqrt = fn x -> sqrt_iter.(sqrt_iter, 1, x) end
+
+IO.puts(sqrt.(4))
+IO.puts(sqrt.(3))
+
+new_if = fn predicate, then_clause, else_clause ->
+  cond do
+    predicate -> then_clause
+    true -> else_clause
+  end
+end
+
+sqrt_iter_alyssa = fn function, guess, x ->
+  new_if.(good_enough?.(guess, x), guess, function.(function, improve.(guess, x), x))
+end
+
+sqrt_alyssa = fn x -> sqrt_iter_alyssa.(sqrt_iter_alyssa, 1, x) end
+
+# IO.puts(new_if.(2 == 3, 0, 5))
+# IO.puts(new_if.(1 == 1, 0, 5))
+
+# In the applicative-order evluation the code will enter in a loop. 
+# If use 'if' the code will run normally. 
+# IO.puts(sqrt_alyssa.(4))

1.1-TheElementsOfProgramming/ex-1.7/icarosun.ex

@@ -0,0 +1,33 @@
+average = fn x, y ->
+  (x + y) / 2
+end
+
+improve = fn guess, x ->
+  average.(guess, x / guess)
+end
+
+good_enough? = fn oldguess, guess ->
+  abs(oldguess - guess) < 0.001
+end
+
+sqrt_iter = fn function, oldguess, guess, x ->
+  if good_enough?.(oldguess, guess) do
+    guess
+  else
+    IO.puts(guess)
+    function.(function, guess, improve.(guess, x), x)
+  end
+end
+
+sqrt = fn x -> sqrt_iter.(sqrt_iter, 1, 2, x) end
+
+IO.puts("Call function to 4")
+IO.puts(sqrt.(4))
+IO.puts("Call function to 8")
+IO.puts(sqrt.(8))
+IO.puts("Call function to 36")
+IO.puts(sqrt.(36))
+IO.puts("Call function to 100")
+IO.puts(sqrt.(100))
+IO.puts("Call function to 112")
+IO.puts(sqrt.(112))

1.1-TheElementsOfProgramming/ex-1.8/icarosun.ex

@@ -0,0 +1,23 @@
+square = fn x -> x * x end
+
+improve = fn x, y ->
+  (x / square.(y) + 2 * y) / 3
+end
+
+cube = fn x -> x * x * x end
+
+good_enough? = fn guess, x ->
+  abs(cube.(guess) - x) < 0.001
+end
+
+cbrt_iter = fn function, guess, x ->
+  if good_enough?.(guess, x) do
+    guess
+  else
+    function.(function, improve.(x, guess), x)
+  end
+end
+
+cbrt = fn x -> cbrt_iter.(cbrt_iter, 1, x) end
+
+IO.puts(cbrt.(1000))