June 2018 Update

Task/Extend-your-language/Go/extend-your-language.go

@@ -0,0 +1,58 @@
+package main
+
+import "fmt"
+
+type F func()
+
+type If2 struct {cond1, cond2 bool}
+
+func (i If2) else1(f F) If2 {
+    if i.cond1 && !i.cond2 {
+        f()
+    }
+    return i
+}
+
+func (i If2) else2(f F) If2 {
+    if i.cond2 && !i.cond1 {
+        f()
+    }
+    return i
+}
+
+func (i If2) else0(f F) If2 {
+    if !i.cond1 && !i.cond2 {
+        f()
+    }
+    return i
+}
+
+func if2(cond1, cond2 bool, f F) If2 {
+    if cond1 && cond2 {
+        f()
+    }
+    return If2{cond1, cond2}
+}
+
+func main() {
+    a, b := 0, 1
+    if2 (a == 1, b == 3, func() {
+        fmt.Println("a = 1 and b = 3")
+    }).else1 (func() {
+        fmt.Println("a = 1 and b <> 3")
+    }).else2 (func() {
+        fmt.Println("a <> 1 and b = 3")
+    }).else0 (func() {
+        fmt.Println("a <> 1 and b <> 3")
+    })
+
+    // It's also possible to omit any (or all) of the 'else' clauses or to call them out of order
+    a, b = 1, 0
+    if2 (a == 1, b == 3, func() {
+        fmt.Println("a = 1 and b = 3")
+    }).else0 (func() {
+        fmt.Println("a <> 1 and b <> 3")
+    }).else1 (func() {
+        fmt.Println("a = 1 and b <> 3")
+    })
+}