From cfd7ab8a0ba1a91d56ff8432895c03e98d680750 Mon Sep 17 00:00:00 2001
From: V <vlad@dev.local>
Date: Sat, 30 Aug 2025 19:14:01 +0100
Subject: [PATCH] Sync

---
 tour_of_go/l4/2                             | 39 ---------------------
 tour_of_go/l4/exercise-fibonacci-closure.go | 28 +++++++++++++++
 tour_of_go/l4/exercise-maps.go              | 26 ++++++++++++++
 tour_of_go/l4/exercise-slices.go            | 26 ++++++++++++++
 tour_of_go/l4/function-closures.go          | 20 +++++++++++
 tour_of_go/l4/function-values.go            | 21 +++++++++++
 tour_of_go/l4/go.mod                        |  5 +++
 tour_of_go/l4/go.sum                        |  2 ++
 tour_of_go/l4/maps.go                       | 35 ++++++++++++++++++
 tour_of_go/l4/mutating-maps.go              | 16 +++++++++
 10 files changed, 179 insertions(+), 39 deletions(-)
 delete mode 100644 tour_of_go/l4/2
 create mode 100644 tour_of_go/l4/exercise-fibonacci-closure.go
 create mode 100644 tour_of_go/l4/exercise-maps.go
 create mode 100644 tour_of_go/l4/exercise-slices.go
 create mode 100644 tour_of_go/l4/function-closures.go
 create mode 100644 tour_of_go/l4/function-values.go
 create mode 100644 tour_of_go/l4/go.mod
 create mode 100644 tour_of_go/l4/go.sum
 create mode 100644 tour_of_go/l4/maps.go
 create mode 100644 tour_of_go/l4/mutating-maps.go

diff --git a/tour_of_go/l4/2 b/tour_of_go/l4/2
deleted file mode 100644
index fda8946..0000000
--- a/tour_of_go/l4/2
+++ /dev/null
@@ -1,39 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-	var aa [2]string
-
-	aa[0] = "Hello"
-	aa[1] = "World"
-	fmt.Println(aa[0], aa[1])
-	fmt.Println(aa)
-
-	primes := [6]int{2, 3, 5, 7, 11, 13}
-	fmt.Println(primes)
-
-	var s []int = primes[1:4]
-	fmt.Printf("The primes are %d and the slice is %d", primes, s)
-
-	// Slices are references to array sections
-	// Changing elements in a slice results in changes to the array
-	// So other slices referencing the same array section will also be changed
-
-	names := [4]string{
-		"John",
-		"Paul",
-		"George",
-		"Ringo",
-	}
-	fmt.Println(names)
-
-	a := names[0:2]
-	b := names[1:3]
-	fmt.Println(a, b)
-
-	// Now make some changes
-	b[0] = "XXX"
-	fmt.Println(a, b)
-	fmt.Println(names)
-}
diff --git a/tour_of_go/l4/exercise-fibonacci-closure.go b/tour_of_go/l4/exercise-fibonacci-closure.go
new file mode 100644
index 0000000..ce71575
--- /dev/null
+++ b/tour_of_go/l4/exercise-fibonacci-closure.go
@@ -0,0 +1,28 @@
+package main
+
+import "fmt"
+
+func fibonacci() func() int {
+	previous := 0
+	current := 0
+	result := 0
+	return func() int {
+		if current == 0 {
+			current = 1
+		} else if current == 1 && result == 0 {
+			result = current
+		} else {
+			result = previous + current
+			previous = current
+			current = result
+		}
+		return result
+	}
+}
+
+func main() {
+	f := fibonacci()
+	for i := 0; i < 10; i++ {
+		fmt.Println(f())
+	}
+}
diff --git a/tour_of_go/l4/exercise-maps.go b/tour_of_go/l4/exercise-maps.go
new file mode 100644
index 0000000..7af13ff
--- /dev/null
+++ b/tour_of_go/l4/exercise-maps.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"golang.org/x/tour/wc"
+	"strings"
+)
+
+func WordCount(s string) map[string]int {
+	result := map[string]int{}
+	fields := strings.Fields(s)
+	for i := range fields {
+		word := fields[i]
+		_, exists := result[word]	
+		if exists == true {
+			result[word] += 1
+		} else {
+			result[word] = 1
+		}
+	} 
+	return result
+}
+
+func main() {
+	wc.Test(WordCount)
+}
+
diff --git a/tour_of_go/l4/exercise-slices.go b/tour_of_go/l4/exercise-slices.go
new file mode 100644
index 0000000..d3fc755
--- /dev/null
+++ b/tour_of_go/l4/exercise-slices.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"golang.org/x/tour/pic"
+	"fmt"
+)
+
+func Pic(dx, dy int) [][]uint8 {
+	pic := make([][]uint8, dy)
+	for i := range(dy) {
+		inner_slice := make([]uint8, dx)
+		for y := range(dx) {
+			res := i * y
+			inner_slice[y] = uint8(res) 
+			
+		}
+		pic[i] = inner_slice
+	}
+	return pic
+}
+
+func main() {
+	s := Pic(8, 8)
+	fmt.Println(s)
+	pic.Show(Pic)
+}
diff --git a/tour_of_go/l4/function-closures.go b/tour_of_go/l4/function-closures.go
new file mode 100644
index 0000000..08c20b0
--- /dev/null
+++ b/tour_of_go/l4/function-closures.go
@@ -0,0 +1,20 @@
+package main
+
+import "fmt"
+
+func adder() func(int) int {
+	sum := 0
+	return func(x int) int {
+		sum += x
+		return sum
+	}
+}
+
+func main() {
+	pos, neg := adder(), adder()
+	for i := 0; i < 10; i++ {
+		fmt.Println(
+			pos(i), neg(-2*i),
+		)
+	}
+}
diff --git a/tour_of_go/l4/function-values.go b/tour_of_go/l4/function-values.go
new file mode 100644
index 0000000..73ad407
--- /dev/null
+++ b/tour_of_go/l4/function-values.go
@@ -0,0 +1,21 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+func compute(fn func(float64, float64) float64) float64 {
+	return fn(3,4)
+}
+
+func main() {
+	hypot := func(x, y float64) float64 {
+		return math.Sqrt(x*x + y*y)
+	}
+
+	fmt.Println(hypot(5, 12))
+
+	fmt.Println(compute(hypot))
+	fmt.Println(compute(math.Pow))
+}
diff --git a/tour_of_go/l4/go.mod b/tour_of_go/l4/go.mod
new file mode 100644
index 0000000..2811f45
--- /dev/null
+++ b/tour_of_go/l4/go.mod
@@ -0,0 +1,5 @@
+module exercise-maps.go
+
+go 1.24.5
+
+require golang.org/x/tour v0.1.0
diff --git a/tour_of_go/l4/go.sum b/tour_of_go/l4/go.sum
new file mode 100644
index 0000000..cde48ea
--- /dev/null
+++ b/tour_of_go/l4/go.sum
@@ -0,0 +1,2 @@
+golang.org/x/tour v0.1.0 h1:OWzbINRoGf1wwBhKdFDpYwM88NM0d1SL/Nj6PagS6YE=
+golang.org/x/tour v0.1.0/go.mod h1:DUZC6G8mR1AXgXy73r8qt/G5RsefKIlSj6jBMc8b9Wc=
diff --git a/tour_of_go/l4/maps.go b/tour_of_go/l4/maps.go
new file mode 100644
index 0000000..8192c54
--- /dev/null
+++ b/tour_of_go/l4/maps.go
@@ -0,0 +1,35 @@
+package main
+
+import "fmt"
+
+type Vertex struct {
+	Lat, Long float64
+}
+
+var m map[string]Vertex
+var new_m = map[string]Vertex{
+	"Bell Labs": Vertex{
+		40.68433, -74.39967,
+	},
+	"Google": Vertex{
+		37.42202, -122.08408,
+	},
+}
+
+// The above can also be written
+var new_new_m = map[string]Vertex{
+	"Bell Labs": {40.68433, -74.39967},
+	"Google": {37.42202, -122.08408},
+}
+
+func main() {
+	m = make(map[string]Vertex)
+	m["Bell Labs"] = Vertex{
+		40.68433, -74.39967,
+	}
+	fmt.Println(m["Bell Labs"])
+
+
+	fmt.Println(new_m)
+	fmt.Println(new_new_m)
+}
diff --git a/tour_of_go/l4/mutating-maps.go b/tour_of_go/l4/mutating-maps.go
new file mode 100644
index 0000000..ce047d9
--- /dev/null
+++ b/tour_of_go/l4/mutating-maps.go
@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+runc main() {
+	m := make(map[string]int)
+
+	m["Answer"] = 42
+	fmt.Println("The value:", m["Answer"])
+
+	delete(m, "Answer")
+	fmt.Println("The value:", m["Answer"])
+
+	v, ok := m["Answer"]
+	fmt.Println("The value:", v, "Present?", ok)
+}