readme: fix Range description

The usefulness of this feature is questionable, and its correct implementation
is difficult due to the use of generics. The implementation worked incorrectly
in cases where the iterator step is not equal to one and is not a multiple of
the end element. For example, for `range(0, 7, 4)`, the result is `[0]`
instead of `[0, 4]`. After this commit range end value is always included.

To check for multiples, a user-defined type must also implement an overload of
the remainder operator (`%`), even if the exclusivity function is not needed.

Another correct implementation requires subtracting one from the end element
for integers and the minimum fractional part supported by the type for floats.
This cannot be done correctly for generics, as it requires casting the literal
to a specific type, and we cannot cast number to any type.

README.md

@@ -3,7 +3,7 @@
 The `ranges` module provides tools for creating ranges of numbers.
 
 Ranges are represented by the generic `Range` iterator, which has start and
-end points, a step size, and an inclusive/exclusive flag.
+end points, and a step size.
 
 ```v
 import ranges

ranges.v

@@ -22,30 +22,18 @@ pub fn (mut r Range[T]) next() ?T {
 	return r.cur
 }
 
-@[params]
-pub struct RangeConfig {
-pub:
-	// If true exclude the end value from range.
-	exclusive bool
-}
-
 // range creates new Range iterator with given start, end and step values.
 //
 // Generally numbers are expected. If type is a struct the following operators
 // must be overloaded to perform comparisons and arithmetics: `+`, `-`, `<`, `==`.
 // See https://docs.vlang.io/limited-operator-overloading.html for details.
 //
-// By default, the range includes the end value. This behavior can be changed
-// by enabling the 'exclusive' option.
+// The range includes the end value.
 //
 // Note: Zero step value will cause an infitite loop!
-pub fn range[T](start T, end T, step T, config RangeConfig) Range[T] {
-	mut limit := end
-	if config.exclusive {
-		limit -= step
-	}
+pub fn range[T](start T, end T, step T) Range[T] {
 	return Range[T]{
-		limit:  limit
+		limit:  end
 		step:   step
 		cur:    start
 		is_neg: start > end
@@ -54,7 +42,6 @@ pub fn range[T](start T, end T, step T, config RangeConfig) Range[T] {
 
 @[params]
 pub struct RangeFromStringConfig {
-	RangeConfig
 pub:
 	sep       string = '-'
 	group_sep string = ','
@@ -92,7 +79,7 @@ pub fn from_string[T](s string, config RangeFromStringConfig) ![]Range[T] {
 			convert_string[T](range_str[0])!,
 			convert_string[T](range_str[1])!,
 			convert_string[T](range_str[2])!,
-			config.RangeConfig)
+		)
 		// vfmt on
 	}
 	return result
@@ -133,7 +120,7 @@ pub fn from_string_custom[T](s string, conv StringConvertFn[T], config RangeFrom
 		start := conv[T](range_str[0])!
 		end := conv[T](range_str[1])!
 		step := conv[T](range_str[2])!
-		result << range(start, end, step, config.RangeConfig)
+		result << range(start, end, step)
 	}
 	return result
 }

ranges_test.v

@@ -9,14 +9,6 @@ fn test_range() {
 	assert result == [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
 }
 
-fn test_range_exclusive() {
-	mut result := []int{}
-	for i in ranges.range[int](0, 10, 1, exclusive: true) {
-		result << i
-	}
-	assert result == [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
-}
-
 fn test_range_negative() {
 	mut result := []int{}
 	for i in ranges.range[int](10, 0, -1) {
@@ -25,14 +17,6 @@ fn test_range_negative() {
 	assert result == [10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
 }
 
-fn test_range_negative_exclusive() {
-	mut result := []int{}
-	for i in ranges.range[int](10, 0, -1, exclusive: true) {
-		result << i
-	}
-	assert result == [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
-}
-
 fn test_range_with_step() {
 	mut result := []int{}
 	for i in ranges.range[int](0, 10, 2) {
@@ -65,14 +49,6 @@ fn test_range_single_item() {
 	assert result == [0]
 }
 
-fn test_range_single_item_exclusive() {
-	mut result := []int{}
-	for i in ranges.range(0, 1, 1, exclusive: true) {
-		result << i
-	}
-	assert result == [0]
-}
-
 fn test_range_bigint() {
 	start := big.zero_int
 	end := big.integer_from_int(5)

v.mod

@@ -1,7 +1,7 @@
 Module {
 	name: 'ranges'
 	description: 'Operating with ranges of numbers'
-	version: '0.1.0'
+	version: '0.2.0'
 	license: 'Unlicense'
 	dependencies: []
 }