docs: fix functions in array/map example (#8695)

doc/docs.md

@@ -1700,14 +1700,15 @@ fn main() {
 	res := run(5, fn (n int) int {
 		return n + n
 	})
+	println(res) // "10"
 	// You can even have an array/map of functions:
 	fns := [sqr, cube]
-	println((10)) // "100"
+	println(fns[0](10)) // "100"
 	fns_map := map{
 		'sqr':  sqr
 		'cube': cube
 	}
-	println((2)) // "8"
+	println(fns_map['cube'](2)) // "8"
 }
 ```
 

vlib/v/ast/str.v

@@ -241,6 +241,9 @@ pub fn (x Expr) str() string {
 			if x.name.starts_with('${x.mod}.') {
 				return util.strip_main_name('${x.name}($sargs)')
 			}
+			if x.mod == '' && x.name == '' {
+				return x.left.str() + '($sargs)'
+			}
 			return '${x.mod}.${x.name}($sargs)'
 		}
 		CharLiteral {
@@ -273,6 +276,14 @@ pub fn (x Expr) str() string {
 		InfixExpr {
 			return '$x.left.str() $x.op.str() $x.right.str()'
 		}
+		MapInit {
+			mut pairs := []string{}
+			for ik, kv in x.keys {
+				mv := x.vals[ik].str()
+				pairs << '$kv: $mv'
+			}
+			return 'map{ ${pairs.join(' ')} }'
+		}
 		ParExpr {
 			return '($x.expr)'
 		}
@@ -321,7 +332,7 @@ pub fn (x Expr) str() string {
 			return res.join('')
 		}
 		StringLiteral {
-			return '"$x.val"'
+			return "'$x.val'"
 		}
 		Type {
 			return 'Type($x.typ)'

vlib/v/checker/tests/prefix_err.out

@@ -33,7 +33,7 @@ vlib/v/checker/tests/prefix_err.vv:9:6: error: cannot take the address of 10
       |      ^
    10 | _ := &"Hi"
    11 | _ := &"${b}"
-vlib/v/checker/tests/prefix_err.vv:10:6: error: cannot take the address of "Hi"
+vlib/v/checker/tests/prefix_err.vv:10:6: error: cannot take the address of 'Hi'
     8 | _ := &(get() + 1)
     9 | _ := &10
    10 | _ := &"Hi"

vlib/v/fmt/fmt.v

@@ -1808,6 +1808,9 @@ pub fn (mut f Fmt) call_expr(node ast.CallExpr) {
 			f.write('$name')
 		}
 	}
+	if node.mod == '' && node.name == '' {
+		f.write(node.left.str())
+	}
 	f.write_generic_if_require(node)
 	f.write('(')
 	f.call_args(node.args)

vlib/v/fmt/tests/maps_of_fns_with_string_keys_keep.vv

@@ -0,0 +1,13 @@
+fn sqr(n int) int {
+	return n * n
+}
+
+fn main() {
+	fns := [sqr]
+	println(fns[0](10))
+	fns_map := map{
+		'sqr': sqr
+	}
+	println(fns_map['sqr'])
+	println(fns_map['sqr'](2))
+}