add: advanced funcs

27-functions-advanced/02-func-values/main.go

@@ -0,0 +1,52 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+type filterFunc func(int) bool
+
+func main() {
+	signatures()
+	funcValues()
+}
+
+func isEven(n int) bool {
+	return n%2 == 0
+}
+
+func isOdd(m int) bool {
+	return m%2 == 1
+}
+
+func signatures() {
+	fmt.Println("••• FUNC SIGNATURES (TYPES) •••")
+	fmt.Printf("isEven     : %T\n", isEven)
+	fmt.Printf("isOdd      : %T\n", isOdd)
+}
+
+func funcValues() {
+	fmt.Println("\n••• FUNC VALUES (VARS) •••")
+
+	// var value func(int) bool
+	var value filterFunc
+	fmt.Printf("value nil? : %t\n", value == nil)
+
+	value = isEven
+	fmt.Printf("value(2)   : %t\n", value(2))
+	fmt.Printf("isEven(2)  : %t\n", isEven(2))
+
+	value = isOdd
+	fmt.Printf("value(1)   : %t\n", value(1))
+	fmt.Printf("isOdd(1)   : %t\n", isOdd(1))
+
+	fmt.Printf("value nil? : %t\n", value == nil)
+	fmt.Printf("value      : %p\n", value)
+	fmt.Printf("isEven     : %p\n", isEven)
+	fmt.Printf("isOdd      : %p\n", isOdd)
+}

27-functions-advanced/03-func-values-part-2/main.go

@@ -0,0 +1,66 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+type filterFunc func(int) bool
+
+func main() {
+	signatures()
+
+	fmt.Println("\n••• WITHOUT FUNC VALUES •••")
+	nums := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+
+	fmt.Printf("evens      : %d\n", filterEvens(nums...))
+	fmt.Printf("odds       : %d\n", filterOdds(nums...))
+
+	fmt.Println("\n••• FUNC VALUES •••")
+	fmt.Printf("evens      : %d\n", filter(isEven, nums...))
+	fmt.Printf("odds       : %d\n", filter(isOdd, nums...))
+}
+
+func filter(f filterFunc, nums ...int) (filtered []int) {
+	for _, n := range nums {
+		if f(n) {
+			filtered = append(filtered, n)
+		}
+	}
+	return
+}
+func filterOdds(nums ...int) (filtered []int) {
+	for _, n := range nums {
+		if isOdd(n) {
+			filtered = append(filtered, n)
+		}
+	}
+	return
+}
+
+func filterEvens(nums ...int) (filtered []int) {
+	for _, n := range nums {
+		if isEven(n) {
+			filtered = append(filtered, n)
+		}
+	}
+	return
+}
+
+func isEven(n int) bool {
+	return n%2 == 0
+}
+
+func isOdd(m int) bool {
+	return m%2 == 1
+}
+
+func signatures() {
+	fmt.Println("••• FUNC SIGNATURES (TYPES) •••")
+	fmt.Printf("isEven     : %T\n", isEven)
+	fmt.Printf("isOdd      : %T\n", isOdd)
+}

27-functions-advanced/04-func-literals/main.go

@@ -0,0 +1,63 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+type filterFunc func(int) bool
+
+func main() {
+	nums := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+
+	fmt.Println("••• FUNC VALUES •••")
+	fmt.Printf("evens      : %d\n", filter(isEven, nums...))
+	fmt.Printf("odds       : %d\n", filter(isOdd, nums...))
+	fmt.Printf("> 3        : %d\n", filter(greaterThan3, nums...))
+	fmt.Printf("> 6        : %d\n", filter(greaterThan6, nums...))
+
+	// ========================================================================
+
+	fmt.Println("\n••• FUNC LITERALS •••")
+
+	var min int
+	greaterThan := func(n int) bool {
+		return n > min
+	}
+
+	min = 3
+	fmt.Printf("> 3        : %d\n", filter(greaterThan, nums...))
+
+	min = 6
+	fmt.Printf("> 6        : %d\n", filter(greaterThan, nums...))
+
+	// ========================================================================
+
+	fmt.Println("\n••• HIGHER-ORDER FUNCS •••")
+	fmt.Printf("> 3        : %d\n", filter(greater(3), nums...))
+	fmt.Printf("> 6        : %d\n", filter(greater(6), nums...))
+}
+
+func greater(min int) filterFunc {
+	return func(n int) bool {
+		return n > min
+	}
+}
+
+func greaterThan6(n int) bool { return n > 6 }
+func greaterThan3(n int) bool { return n > 3 }
+func isEven(n int) bool       { return n%2 == 0 }
+func isOdd(m int) bool        { return m%2 == 1 }
+
+func filter(f filterFunc, nums ...int) (filtered []int) {
+	for _, n := range nums {
+		if f(n) {
+			filtered = append(filtered, n)
+		}
+	}
+	return
+}

27-functions-advanced/05-func-literals-part-2/main.go

@@ -0,0 +1,97 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+)
+
+type filterFunc func(int) bool
+
+func main() {
+	fmt.Println("••• HIGHER-ORDER FUNCS •••")
+
+	nums := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+
+	odd := reverse(reverse(isEven))
+	fmt.Printf("reversed   : %t\n", odd(8))
+
+	fmt.Printf("> 3        : %d\n", filter(greater(3), nums...))
+	fmt.Printf("> 6        : %d\n", filter(greater(6), nums...))
+	fmt.Printf("<= 6       : %d\n", filter(lesseq(6), nums...))
+	fmt.Printf("<= 6       : %d\n", filter(reverse(greater(6)), nums...))
+
+	fmt.Println("\n••• CLOSURES •••")
+	fmt.Printf("uniques    : %d\n", filter(uniques(), 1, 1, 2, 3, 3))
+
+	dups := reverse(uniques())
+	fmt.Printf("dups       : %v\n", filter(dups, 1, 1, 2, 3, 3))
+
+	dups = reverse(uniques())
+	fmt.Printf("dups dups  : %v\n", filter(dups, 1, 1, 2, 3, 3, 3, 3))
+
+	dups = reverse(uniques())
+	out := filter(dups, 1, 1, 2, 3, 3, 3, 3)
+	fmt.Printf("dups uniqs : %v\n", filter(uniques(), out...))
+
+	dups = reverse(uniques())
+	chained := chain(reverse(greater(2)), dups, uniques())
+	fmt.Printf("dups chain : %v\n", filter(chained, 1, 1, 2, 3, 3, 3, 3, 0, 0))
+}
+
+func chain(filters ...filterFunc) filterFunc {
+	return func(n int) bool {
+		for _, next := range filters {
+			if !next(n) {
+				return false
+			}
+		}
+		return true
+	}
+}
+
+func uniques() filterFunc {
+	seen := make(map[int]bool)
+
+	return func(n int) (ok bool) {
+		if !seen[n] {
+			seen[n], ok = true, true
+		}
+		return
+	}
+}
+
+func reverse(f filterFunc) filterFunc {
+	return func(n int) bool {
+		return !f(n)
+	}
+}
+
+func greater(min int) filterFunc {
+	return func(n int) bool {
+		return n > min
+	}
+}
+
+func filter(f filterFunc, nums ...int) (filtered []int) {
+	for _, n := range nums {
+		if f(n) {
+			filtered = append(filtered, n)
+		}
+	}
+	return
+}
+
+func isEven(n int) bool { return n%2 == 0 }
+func isOdd(m int) bool  { return m%2 == 1 }
+
+func lesseq(max int) filterFunc {
+	return func(n int) bool {
+		return n <= max
+	}
+}

27-functions-advanced/exercises/README.md

@@ -0,0 +1,8 @@
+# IDEAS
+
+* Create a chainable funcs for strings
+* Create a mapper instead of a filter
+* Create map/reduce
+* Create a time it takes higher-order func
+* Use stdlib funcs with func values
+* Create a functional program with structs (filter etc)