String concatination.

examples/strings_test.fun

@@ -0,0 +1,34 @@
+#!/usr/bin/env fun
+// Strings test: concatenation with variables and literals, functions returning strings
+
+print("=== strings test start ===")
+
+string a = "Hello"
+string b = "World"
+string sep = ", "
+string excl = "!"
+
+// Basic concatenations
+print(a + sep + b + excl)         // expect: Hello, World!
+print("Hi" + " " + "there")       // expect: Hi there
+
+// Empty strings
+string empty = ""
+print(empty + "x")                 // expect: x
+print("x" + empty)                 // expect: x
+
+// Function returning concatenated string
+fun greet(name)
+  return "Hello, " + name
+
+print(greet("Fun"))                // expect: Hello, Fun
+
+// Using a variable prefix with a function result
+string prefix = "Hi, "
+print(prefix + greet("You"))       // expect: Hi, Hello, You
+
+// Non-empty check (string comparison)
+if (a != "")
+  print("a is non-empty")
+
+print("=== strings test end ===")