Add Vector.take and Vector.drop functions (#3629)

Implements https://www.pivotaltracker.com/story/show/182307048

CHANGELOG.md

@@ -171,6 +171,8 @@
   type from `Standard.Table`.][3601]
 - [Created `Index_Sub_Range` type and updated `Text.take` and
   `Text.drop`.][3617]
+- [Updated `Vector.take` and `Vector.drop` and removed their obsolete
+  counterparts.][3629]
 
 [debug-shortcuts]:
   https://github.com/enso-org/enso/blob/develop/app/gui/docs/product/shortcuts.md#debug
@@ -270,6 +272,7 @@
 [3593]: https://github.com/enso-org/enso/pull/3593
 [3601]: https://github.com/enso-org/enso/pull/3601
 [3617]: https://github.com/enso-org/enso/pull/3617
+[3629]: https://github.com/enso-org/enso/pull/3629
 
 #### Enso Compiler
 

distribution/lib/Standard/Base/0.0.0-dev/src/Data/Range.enso

@@ -127,6 +127,30 @@ type Range
             if self.step < 0 then go (<=) self.start else
                 throw_zero_step_error
 
+    ## PRIVATE
+       Applies a function to each element of the range.
+
+       Essentially acts like `range.to_vector.each_with_index`, but it is more
+       efficient.
+
+       Arguments:
+       - function: A function to apply that takes two parameters: first the
+         index of a given range element and then the actual range element.
+
+       > Example
+         Print range elements with their indices within the range.
+
+             (10.up_to 13).each_with_index ix-> elem-> IO.println (Pair ix elem) # Will print Pair 0 10, Pair 1 11, Pair 2 12
+    each_with_index : (Integer -> Any -> Any) -> Nothing
+    each_with_index self function =
+        go end_condition ix current =
+            if end_condition current self.end then Nothing else
+                function ix current
+                @Tail_Call go end_condition ix+1 current+self.step
+        if self.step > 0 then go (>=) 0 self.start else
+            if self.step < 0 then go (<=) 0 self.start else
+                throw_zero_step_error
+
     ## Combines all the elements of the range, by iteratively applying the
        passed function with next elements of the range.
 

distribution/lib/Standard/Base/0.0.0-dev/src/Data/Text/Extensions.enso

@@ -1099,10 +1099,7 @@ Text.take self range=(First 1) =
         Range start end _ ->
             Text_Utils.substring self start end
         Text_Sub_Range.Codepoint_Ranges char_ranges _ ->
-            sb = StringBuilder.new
+            slice_text self char_ranges
-            char_ranges.map char_range->
-               sb.append self char_range.start char_range.end
-            sb.toString
 
 ## ALIAS skip, remove
    Creates a new Text by removing the specified range of the input.
@@ -1152,12 +1149,9 @@ Text.drop self range=(First 1) =
                     prefix + Text_Utils.drop_first self end
         Text_Sub_Range.Codepoint_Ranges _ _ ->
             sorted_char_ranges_to_remove = ranges.sorted_and_distinct_ranges
-            len = Text_Utils.char_length self
+            char_length = Text_Utils.char_length self
-            sb = StringBuilder.new
+            inverted = Vector.invert_range_selection sorted_char_ranges_to_remove char_length needs_sorting=False
-            ranges_with_sentinels = [Range 0 0] + sorted_char_ranges_to_remove + [Range len len]
+            slice_text self inverted
-            ranges_with_sentinels.zip ranges_with_sentinels.tail prev-> next->
-                sb.append self prev.end next.start
-            sb.toString
 
 ## ALIAS lower, upper, title, proper
    Converts each character in `self` to the specified case.
@@ -1504,3 +1498,15 @@ Text.location_of_all self term="" matcher=Text_Matcher = case matcher of
         case matcher.compile term . match self Mode.All of
             Nothing -> []
             matches -> matches.map m-> m.span 0 . to_grapheme_span
+
+## PRIVATE
+   Returns a new Text constructed by slicing the input according to the provided
+   ranges. The ranges are assumed to have step equal to 1 and bounds within the
+   input's range.
+
+   The input ranges are in UTF-16 code unit space.
+slice_text text char_ranges =
+    sb = StringBuilder.new
+    char_ranges.map char_range->
+       sb.append text char_range.start char_range.end
+    sb.toString

distribution/lib/Standard/Base/0.0.0-dev/src/Data/Text/Text_Sub_Range.enso

@@ -1,5 +1,4 @@
 from Standard.Base import all
-import Standard.Base.Runtime.Ref
 from Standard.Base.Data.Text.Extensions import Index_Out_Of_Bounds_Error
 from Standard.Base.Data.Text.Span as Span_Module import Span
 from Standard.Base.Data.Index_Sub_Range import First, Last, While, By_Index, Sample, Every
@@ -118,19 +117,7 @@ type Codepoint_Ranges
        Empty subranges are not discarded.
     sorted_and_distinct_ranges : Vector Range
     sorted_and_distinct_ranges self = if self.is_sorted_and_distinct then self.ranges else
-        sorted = self.ranges.filter (range-> range.is_empty.not) . sort on=(.start)
+        Vector.sort_and_merge_ranges self.ranges
-        if sorted.is_empty then [] else
-            current_ref = Ref.new sorted.first
-            builder = Vector.new_builder
-            sorted.tail.each range->
-                current = current_ref.get
-                case range.start <= current.end of
-                    True -> current_ref.put (Range current.start (Math.max current.end range.end))
-                    False ->
-                        builder.append current
-                        current_ref.put range
-            builder.append current_ref.get
-            builder.to_vector
 
 ## PRIVATE
    Utility function to find char indices for Text_Sub_Range.

distribution/lib/Standard/Base/0.0.0-dev/src/Data/Vector.enso

@@ -1,5 +1,8 @@
 from Standard.Base import all
+import Standard.Base.Runtime.Ref
 import Standard.Base.Runtime.Unsafe
+from Standard.Base.Data.Index_Sub_Range import While, By_Index, Sample, Every
+import Standard.Base.Random
 
 ## Creates a new vector of the given length, initializing elements using
    the provided constructor function.
@@ -90,7 +93,7 @@ new_builder (capacity=1) = Builder.new capacity
 
      If this didn't happen then it would be possible for the underlying array to
      be mutated under the hood, and sneak mutability into our immutable data.
-from_array : Any -> Vector.Vector Any
+from_array : Any -> Vector Any
 from_array arr = new (Polyglot.get_array_size arr) (arr.at _)
 
 ## The basic, immutable, vector type.
@@ -553,7 +556,7 @@ type Vector
     short_display_text : Integer -> Text
     short_display_text self max_entries=10 =
         if max_entries < 1 then Error.throw <| Illegal_Argument_Error "The `max_entries` parameter must be positive." else
-            prefix = self.take_start max_entries
+            prefix = self.take (First max_entries)
             if prefix.length == self.length then self.to_text else
                 remaining_count = self.length - prefix.length
                 remaining_text = if remaining_count == 1 then "and 1 more element" else
@@ -637,7 +640,8 @@ type Vector
             if self.length == 1 then prefix + self.unsafe_at 0 + suffix else
                 prefix + self.unsafe_at 0 + (1.up_to self.length . fold "" acc-> i-> acc + separator + self.unsafe_at i) + suffix
 
-    ## Creates a new vector with the skipping elements until `start` and then
+    ## PRIVATE
+       Creates a new vector with the skipping elements until `start` and then
        continuing until `end` index.
 
        Arguments:
@@ -648,89 +652,81 @@ type Vector
          Remove the first 2 elements then continue until index 5 from the vector.
 
              [1, 2, 3, 4, 5, 6, 7, 8].slice 2 5 == [3, 4, 5]
-    take : Integer -> Integer -> Vector Any
+    slice : Integer -> Integer -> Vector Any
-    take self start end =
+    slice self start end =
         slice_start = Math.max 0 start
         slice_end = Math.min self.length end
-        if slice_start >= slice_end then Vector (Array.new 0) else
+        if slice_start >= slice_end then [] else
             if (slice_start == 0) && (slice_end == self.length) then self else
                 len = slice_end - slice_start
                 arr = Array.new len
                 Array.copy self.to_array slice_start arr 0 len
                 Vector arr
 
-    ## Creates a new vector with the first `count` elements in `self` removed.
+    ## Creates a new vector with only the specified range of elements from the
+       input, removing any elements outside the range.
 
        Arguments:
-       - count: The number of elements to drop from the start of `self`.
+       - range: The section of the this Vector to return.
+         If an `Index_Sub_Range`, then the selection is interpreted following
+         the rules of that type.
+         If a `Range`, the selection is specified by two indices, from and to.
+    take : (Index_Sub_Range | Range) -> Vector Any
+    take self range=(First 1) = case range of
+        Range _ _ _ -> self.take (By_Index range)
+        First count -> self.slice 0 (Math.min self.length count)
+        Last count -> self.slice self.length-count self.length
+        While predicate ->
+            end = 0.up_to self.length . find i-> (predicate (self.at i)).not
+            if end.is_nothing then self else self.slice 0 end
+        By_Index one_or_many_descriptors -> Panic.recover [Index_Out_Of_Bounds_Error, Illegal_Argument_Error] <|
+            indices = case one_or_many_descriptors of
+                Vector _ -> one_or_many_descriptors
+                _ -> [one_or_many_descriptors]
+            trimmed = resolve_ranges indices self.length
+            slice_ranges self trimmed
+        Sample count seed ->
+            rng = Random.new seed
+            Random.sample self count rng
+        Every step start ->
+            if step <= 0 then Error.throw (Illegal_Argument_Error "Step within Every must be positive.") else
+                if start >= self.length then [] else
+                    range = Range start self.length step
+                    self.take (By_Index range)
 
-       > Example
+    ## Creates a new vector with only the specified range of elements from the
-         Remove the first element from the start of the vector.
+       input, removing any elements outside the range.
-
-             [1, 2, 3, 4, 5].drop_start 1
-    drop_start : Integer -> Vector Any
-    drop_start self count = self.take count self.length
-
-    ## Creates a new vector with elements at the beginning of the vector which
-       satisfy the provided predicate removed.
 
        Arguments:
-       - predicate: A function returning `Boolean` specifying the prefix to
+       - range: The section of the this Vector to return.
-         remove.
+         If an `Index_Sub_Range`, then the selection is interpreted following
-
+         the rules of that type.
-       > Example
+         If a `Range`, the selection is specified by two indices, from and to.
-         Remove any odd elements at the beginining of the vector (but keeping
+    drop : (Index_Sub_Range | Range) -> Vector Any
-         any odd elements later on).
+    drop self range=(First 1) = case range of
-
+        Range _ _ _ -> self.drop (By_Index range)
-             [1, 3, 5, 6, 8, 9, 10, 11, 13].drop_while (x-> x%2 == 1) == [6, 8, 9, 10, 11, 13]
+        First count -> self.slice count self.length
-    drop_while : (Any -> Boolean) -> Vector Any
+        Last count -> self.slice 0 self.length-count
-    drop_while self predicate =
+        While predicate ->
-        find_first_false current =
+            end = 0.up_to self.length . find i-> (predicate (self.at i)).not
-            if current >= self.length then Nothing else
+            if end.is_nothing then [] else self.slice end self.length
-                case predicate (self.unsafe_at current) of
+        By_Index one_or_many_descriptors -> Panic.recover [Index_Out_Of_Bounds_Error, Illegal_Argument_Error] <|
-                    False -> current
+            indices = case one_or_many_descriptors of
-                    True -> @Tail_Call find_first_false current+1
+                Vector _ -> one_or_many_descriptors
-        case find_first_false 0 of
+                _ -> [one_or_many_descriptors]
-            Nothing -> []
+            trimmed = resolve_ranges indices self.length
-            first_false -> self.take first_false self.length
+            normalized = normalize_ranges trimmed
-
+            inverted = invert_range_selection normalized self.length needs_sorting=True
-    ## Creates a new vector with the last `count` elements in `self` removed.
+            slice_ranges self inverted
-
+        Sample count seed ->
-       Arguments:
+            rng = Random.new seed
-       - count: The number of elements to drop from the end of `self`.
+            indices_to_drop = Random.random_indices self.length count rng
-
+            self.drop (By_Index indices_to_drop)
-       > Example
+        Every step start ->
-         Remove the last two elements from the end of the vector.
+            if step <= 0 then Error.throw (Illegal_Argument_Error "Step within Every must be positive.") else
-
+                if start >= self.length then self else
-             [1, 2, 3, 4, 5].drop_end 2
+                    range = Range start self.length step
-    drop_end : Integer -> Vector Any
+                    self.drop (By_Index range)
-    drop_end self count = self.take 0 (self.length - count)
-
-    ## Creates a new vector, consisting of the first `count` elements on the
-       left of `self`.
-
-       Arguments:
-       - count: The number of elements to take from the start of `self`.
-
-       > Example
-         Create a new vector from the first two elements of the vector.
-
-             [1, 2, 3, 4, 5].take_start 2
-    take_start : Integer -> Vector Any
-    take_start self count = self.take 0 count
-
-    ## Creates a new vector, consisting of the last `count` elements on the
-       right of `self`.
-
-       Arguments:
-       - count: The number of elements to take from the end of `self`.
-
-       > Example
-         Create a new vector from the last two elements of the vector.
-
-             [1, 2, 3, 4, 5].take_end 3
-    take_end : Integer -> Vector Any
-    take_end self count = self.take (self.length - count) self.length
 
     ## Performs a pair-wise operation passed in `function` on consecutive
        elements of `self` and `that`.
@@ -808,7 +804,7 @@ type Vector
 
              [1, 2, 3, 4].tail
     tail : Vector ! Empty_Error
-    tail self = if self.length >= 1 then self.drop_start 1 else
+    tail self = if self.length >= 1 then self.drop (First 1) else
         Error.throw Empty_Error
 
     ## Get the all elements in the vector except the last.
@@ -818,7 +814,7 @@ type Vector
 
              [1, 2, 3, 4].init
     init : Vector ! Empty_Error
-    init self = if self.length >= 1 then self.drop_end 1 else Error.throw Empty_Error
+    init self = if self.length >= 1 then self.drop (Last 1) else Error.throw Empty_Error
 
     ## Get the last element of the vector, or an `Empty_Error` if the vector is
        empty.
@@ -974,7 +970,7 @@ type Vector
        visualization.
     to_default_visualization_data : Text
     to_default_visualization_data self =
-        json = self.take_start 100 . to_json
+        json = self.take (First 100) . to_json
         json.to_text
 
 ## PRIVATE
@@ -1169,3 +1165,115 @@ type Incomparable_Values_Error
 handle_incomparable_value ~function =
     handle t = Panic.catch t handler=(Error.throw Incomparable_Values_Error)
     handle No_Such_Method_Error <| handle Type_Error <| handle Unsupported_Argument_Types <| function
+
+## PRIVATE
+   Resolves a vector of ranges or indices into a vector of ranges that fit
+   within a sequence.
+resolve_ranges : Vector (Integer | Range) -> Integer -> Vector Range
+resolve_ranges ranges length =
+    ## Ensures that a descriptor fits within the range of the current
+       vector, trimming it or reporting an error if it is invalid.
+    trim descriptor = case descriptor of
+        Integer ->
+            actual_index = if descriptor < 0 then length + descriptor else descriptor
+            if (actual_index < 0) || (actual_index >= length) then Panic.throw (Index_Out_Of_Bounds_Error descriptor length) else
+                actual_index
+        Range start end step ->
+            if step <= 0 then Panic.throw (Illegal_Argument_Error "Range step must be positive.") else
+                if (start < 0) || (end < 0) then Panic.throw (Illegal_Argument_Error "Range start and end must not be negative.") else
+                    if start >= length then Panic.throw (Index_Out_Of_Bounds_Error start length) else
+                        actual_end = Math.min end length
+                        if actual_end < start then Range start start step else
+                            Range start actual_end step
+    ranges.map trim
+
+## PRIVATE
+   Creates a new vector where for each range, a corresponding section of the
+   source vector is added to the result.
+
+   Assumes that the ranges have been already bounds-checked (for example by
+   passing them through `resolve_ranges`).
+slice_ranges vector ranges =
+    if ranges.length == 0 then [] else
+        if ranges.length != 1 then slice_many_ranges vector ranges else
+            case ranges.first of
+                Integer -> [vector.unsafe_at ranges.first]
+                Range start end step -> case step == 1 of
+                    True -> vector.slice start end
+                    False -> slice_many_ranges vector ranges
+
+## PRIVATE
+   See `slice_ranges`.
+slice_many_ranges vector ranges =
+    new_length = ranges.fold 0 acc-> descriptor-> case descriptor of
+        Integer -> acc+1
+        Range _ _ _ -> acc+descriptor.length
+    arr = Array.new new_length
+    ranges.fold 0 start_ix-> descriptor-> case descriptor of
+        Integer ->
+            arr.set_at start_ix (vector.unsafe_at descriptor)
+            start_ix+1
+        Range start end step -> case step == 1 of
+            True ->
+                len = end-start
+                Array.copy vector.to_array start arr start_ix len
+                start_ix+len
+            False ->
+                descriptor.each_with_index within_range_ix-> descriptor_ix->
+                    arr.set_at start_ix+within_range_ix (vector.unsafe_at descriptor_ix)
+                start_ix+descriptor.length
+    Vector arr
+
+## PRIVATE
+   Takes a list of descriptors and returns a new one where ranges with
+   non-unitary step have been replaced with series of ranges covering the same
+   set of indices with step equal to 1, and indices have been replaced with
+   single-element ranges.
+normalize_ranges descriptors =
+    normalize descriptor = case descriptor of
+        Integer -> [Range descriptor descriptor+1]
+        Range _ _ _ ->
+            if descriptor.step == 1 then [descriptor] else
+                descriptor.to_vector.map ix->
+                    Range ix ix+1
+    descriptors.flat_map normalize
+
+## PRIVATE
+   Inverts the selection determined by the input list of ranges.
+
+   The input ranges are assumed to be normalized (i.e. all of them have step
+   equal to 1).
+
+   Arguments:
+   - ranges: The list of ranges determining indices which are selected. The
+     result will be a list of ranges containing all the indices which were not
+     originally selected here.
+   - length: Length of the related sequence.
+   - needs_sorting: Determines if `ranges` need to be sorted and merged or if it
+     can be assumed that they are sorted already.
+invert_range_selection : Vector Range -> Integer -> Boolean -> Vector Range
+invert_range_selection ranges length needs_sorting =
+    sorted = if needs_sorting then sort_and_merge_ranges ranges else ranges
+    ranges_with_sentinels = [Range 0 0] + sorted + [Range length length]
+    ranges_with_sentinels.zip ranges_with_sentinels.tail prev-> next->
+        Range prev.end next.start
+
+## PRIVATE
+   Returns a new sorted list of ranges where intersecting ranges have been
+   merged.
+
+   Empty subranges are discarded.
+sort_and_merge_ranges ranges =
+    sorted = ranges.filter (range-> range.is_empty.not) . sort on=(.start)
+    if sorted.is_empty then [] else
+        current_ref = Ref.new sorted.first
+        builder = new_builder
+        sorted.tail.each range->
+            current = current_ref.get
+            case range.start <= current.end of
+                True -> current_ref.put (Range current.start (Math.max current.end range.end))
+                False ->
+                    builder.append current
+                    current_ref.put range
+        builder.append current_ref.get
+        builder.to_vector

distribution/lib/Standard/Base/0.0.0-dev/src/Main.enso

@@ -14,6 +14,7 @@ import project.Data.Ordering.Natural_Order
 import project.Data.Ordering.Sort_Direction
 import project.Data.Pair
 import project.Data.Range
+import project.Data.Index_Sub_Range
 import project.Data.Regression
 import project.Data.Statistics
 import project.Data.Statistics.Rank_Method
@@ -97,3 +98,4 @@ from project.Function export all
 from project.Nothing export all
 from project.Polyglot export all
 from project.Runtime.Extensions export all
+from project.Data.Index_Sub_Range export First, Last

distribution/lib/Standard/Base/0.0.0-dev/src/Runtime.enso

@@ -1,4 +1,5 @@
 import Standard.Base.Data.Vector
+from Standard.Base.Data.Index_Sub_Range import First
 import Standard.Base.Polyglot
 import Standard.Base.Nothing
 from Standard.Base.Runtime.Extensions import Source_Location
@@ -23,7 +24,7 @@ get_stack_trace =
     stack_with_prims = Vector.Vector prim_stack
     stack = stack_with_prims.map wrap_primitive_stack_trace_element
     # drop this frame and the one from `Runtime.primitive_get_stack_trace`
-    stack.drop_start 2
+    stack.drop (First 2)
 
 ## ADVANCED
 

distribution/lib/Standard/Base/0.0.0-dev/src/Warning.enso

@@ -1,4 +1,5 @@
 from Standard.Base import all
+from Standard.Base.Data.Index_Sub_Range import While
 from Standard.Base.Runtime import Stack_Trace_Element
 
 ## A representation of a dataflow warning attached to a value.
@@ -68,7 +69,7 @@ create payload origin = @Builtin_Method "Warning.create"
 attach : Any -> Any -> Any
 attach warning value =
     origin = Runtime.get_stack_trace
-    attach_with_stacktrace value warning (origin.drop_start 1)
+    attach_with_stacktrace value warning (origin.drop (First 1))
 
 ## PRIVATE
 
@@ -175,8 +176,8 @@ map_attached_warnings_helper mapper value frames_to_drop =
             Maybe.Some new_payload ->
                 self_call_name = "Warning.map_attached_warnings_helper"
                 stack_trace = Runtime.get_stack_trace
-                stack_trace_up_to_this_function = stack_trace.drop_while element-> element.name != self_call_name
+                stack_trace_up_to_this_function = stack_trace.drop (While element-> element.name != self_call_name)
-                new_origin = stack_trace_up_to_this_function.drop_start 1+frames_to_drop
+                new_origin = stack_trace_up_to_this_function.drop (First 1+frames_to_drop)
                 create new_payload new_origin
             ## If the mapper did not want to affect this warning, we return the
                original (unwrapped) warning instance.

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Dialect/Postgres.enso

@@ -1,4 +1,4 @@
-from Standard.Base import all
+from Standard.Base import all hiding First, Last
 
 import Standard.Base.Error.Common as Errors
 from Standard.Table.Data.Aggregate_Column import all

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Dialect/SQLite.enso

@@ -1,4 +1,4 @@
-from Standard.Base import all
+from Standard.Base import all hiding First, Last
 
 from Standard.Table.Data.Aggregate_Column import all
 from Standard.Database.Data.Sql import Sql_Type

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Internal/Aggregate_Helper.enso

@@ -1,4 +1,4 @@
-from Standard.Base import all
+from Standard.Base import all hiding First, Last
 from Standard.Base.Data.Text.Text_Ordering import Text_Ordering
 
 from Standard.Table.Data.Aggregate_Column import all

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Table.enso

@@ -598,8 +598,8 @@ type Table
             right_names_before = right_new_columns.map .name
             new_names = combine_names left_names_before right_names_before left_suffix right_suffix
             left_indices_count = left_new_meta_index.length
-            left_new_meta_index_names = new_names.first.take_start left_indices_count
+            left_new_meta_index_names = new_names.first.take (First left_indices_count)
-            left_new_columns_names = new_names.first.drop_start left_indices_count
+            left_new_columns_names = new_names.first.drop (First left_indices_count)
             right_new_columns_names = new_names.second
 
             # Rename columns to the newly allocated names

distribution/lib/Standard/Table/0.0.0-dev/src/Data/Column.enso

@@ -861,7 +861,7 @@ type Column
         size = ['length', self.length]
         name = ['name', self.name]
         max_data = 100
-        data = ['data', self.to_vector.take_start max_data]
+        data = ['data', self.to_vector.take (First max_data)])
         Json.from_pairs [size, name, data] . to_text
 
     ## ALIAS Sum Columns
@@ -1021,7 +1021,7 @@ type Column
 
              import Standard.Examples
 
-             example_take_start = Examples.integer_column.take_start 2
+             example_take_start = Examples.integer_column.take (First 2)
     take_start : Integer -> Column
     take_start self count =
         Column (self.java_column.slice 0 count)

distribution/lib/Standard/Table/0.0.0-dev/src/Data/Table.enso

@@ -219,7 +219,7 @@ type Table
         row_count = ['number_of_rows', self.row_count]
         cols = self.columns.map c->
             name = c.name
-            items = c.to_vector.take_start max_size
+            items = c.to_vector.take (First max_size)
             Json.from_pairs [['name', name], ['data', items]]
         Json.from_pairs [row_count, ['columns', cols]] . to_text
 

distribution/lib/Standard/Table/0.0.0-dev/src/Internal/Aggregate_Column_Helper.enso

@@ -1,4 +1,4 @@
-from Standard.Base import all
+from Standard.Base import all hiding First, Last
 
 from Standard.Table.Data.Column import Column
 from Standard.Table.Data.Aggregate_Column import all

distribution/lib/Standard/Table/0.0.0-dev/src/Internal/Delimited_Reader.enso

@@ -214,7 +214,7 @@ newline_at_eof file encoding =
     file_last_bytes = file.read_last_bytes most_bytes
     result = newlines.zip newline_bytes . find pair->
         bytes = pair.second
-        bytes == (file_last_bytes.take_end bytes.length)
+        bytes == (file_last_bytes.take (Last bytes.length))
     result.first . catch Nothing
 
 ## PRIVATE

distribution/lib/Standard/Table/0.0.0-dev/src/Internal/Table_Helpers.enso

@@ -173,8 +173,8 @@ rename_columns internal_columns mapping on_problems =
         Column_Name_Mapping.By_Position vec ->
             good_names = case vec.length > col_count of
                 True ->
-                    problem_builder.report_other_warning (Too_Many_Column_Names_Provided (vec.drop_start col_count))
+                    problem_builder.report_other_warning (Too_Many_Column_Names_Provided (vec.drop (First col_count)))
-                    vec.take_start col_count
+                    vec.take (First col_count)
                 False -> vec
 
             new_names = 0.up_to col_count . map i->if i>=good_names.length then Nothing else

distribution/lib/Standard/Test/0.0.0-dev/src/Main.enso

@@ -516,14 +516,13 @@ Any.should_be_an self typ = self.should_be_a typ
          example_should_equal = [1, 2] . should_contain_the_same_elements_as [2, 1]
 Any.should_contain_the_same_elements_as : Any -> Integer -> Assertion
 Any.should_contain_the_same_elements_as self that frames_to_skip=0 =
+    loc = Meta.get_source_location 1+frames_to_skip
     that.each element->
         if self.contains element . not then
-            loc = Meta.get_source_location 2+frames_to_skip
             msg = "The collection (" + self.to_text + ") did not contain "+element.to_text+" (at " + loc + ")."
             fail msg
     self.each element->
         if that.contains element . not then
-            loc = Meta.get_source_location 2+frames_to_skip
             msg = "The collection contained an element ("+element.to_text+") which was not expected (at " + loc + ")."
             fail msg
 

distribution/lib/Standard/Visualization/0.0.0-dev/src/Table/Visualization.enso

@@ -53,7 +53,7 @@ prepare_visualization x max_rows = Helpers.recover_errors <| case x of
     # TODO [RW] Should we truncate Vectors?
     # We also visualize Vectors and arrays
     Vector.Vector _ ->
-        truncated = x.take_start max_rows
+        truncated = x.take (First max_rows)
         Json.from_pairs [["json", truncated], ["all_rows_count", x.length]] . to_text
     Array ->
         prepare_visualization (Vector.Vector x) max_rows

std-bits/base/src/main/java/org/enso/base/Random_Utils.java

@@ -8,7 +8,7 @@ public class Random_Utils {
   public static Object[] sample(Object[] array, int k, Random rng) {
     k = Math.min(k, array.length);
     var copy = Arrays.copyOf(array, array.length);
-    shuffleFirstInPlace(copy, k, rng);
+    sampleInPlace(copy, k, rng);
     return Arrays.copyOf(copy, k);
   }
 
@@ -22,11 +22,15 @@ public class Random_Utils {
       indices[i] = (long) i;
     }
     k = Math.min(k, n);
-    shuffleFirstInPlace(indices, k, rng);
+    sampleInPlace(indices, k, rng);
     return Arrays.copyOf(indices, k);
   }
 
-  private static <T> void shuffleFirstInPlace(T[] array, int k, Random rng) {
+  /**
+   * Reorders the array in such a way that the first k elements contain a random selection (without
+   * replacement) of k elements from the whole array.
+   */
+  private static <T> void sampleInPlace(T[] array, int k, Random rng) {
     int n = array.length;
     for (int i = 0; i < Math.min(k, n); ++i) {
       int r = i + rng.nextInt(n - i);

test/Benchmarks/src/Vector.enso

@@ -27,8 +27,8 @@ main =
     Bench.measure (random_vec + [1]) "Append Single" iter_size num_iterations
     Bench.measure (random_vec + random_vec_2) "Append Large" iter_size num_iterations
     Bench.measure (random_vec.sum) "Sum" iter_size num_iterations
-    Bench.measure ((random_vec.drop_start 20).sum) "Drop First 20 and Sum" iter_size num_iterations
+    Bench.measure ((random_vec.drop (First 20)).sum) "Drop First 20 and Sum" iter_size num_iterations
-    Bench.measure ((random_vec.drop_end 20).sum) "Drop Last 20 and Sum" iter_size num_iterations
+    Bench.measure ((random_vec.drop (Last 20)).sum) "Drop Last 20 and Sum" iter_size num_iterations
     Bench.measure (random_vec.filter (x -> x % 3 == 1)) "Filter" iter_size num_iterations
     Bench.measure (random_vec.filter_with_index (i->x -> (i+x) % 3 == 1)) "Filter With Index" iter_size num_iterations
     Bench.measure (random_vec.partition (x -> x % 3 == 1)) "Partition" iter_size num_iterations

test/Table_Tests/src/Aggregate_Column_Spec.enso

@@ -1,4 +1,4 @@
-from Standard.Base import all
+from Standard.Base import all hiding First, Last
 
 import Standard.Table.Data.Table
 from Standard.Table.Data.Aggregate_Column import all

test/Table_Tests/src/Aggregate_Spec.enso

@@ -1,4 +1,4 @@
-from Standard.Base import all
+from Standard.Base import all hiding First, Last
 
 import Standard.Table
 from Standard.Table.Data.Column_Selector import By_Name, By_Index

test/Table_Tests/src/Database/Redshift_Spec.enso

@@ -63,7 +63,7 @@ run_tests connection pending=Nothing =
     agg_in_memory_table = (enso_project.data / "data.csv") . read
     agg_table = connection.upload_table (Name_Generator.random_name "Agg1") agg_in_memory_table
     tables.append agg_table.name
-    empty_agg_table = connection.upload_table (Name_Generator.random_name "Agg_Empty") (agg_in_memory_table.take_start 0)
+    empty_agg_table = connection.upload_table (Name_Generator.random_name "Agg_Empty") (agg_in_memory_table.take (First 0))
     tables.append empty_agg_table.name
     Aggregate_Spec.aggregate_spec prefix agg_table empty_agg_table table_builder materialize is_database=True selection pending=pending
 

test/Table_Tests/src/Table_Spec.enso

@@ -486,12 +486,12 @@ spec =
             t_1.take_start 10 . at 'col' . to_vector . should_equal (t_1.at 'col' . to_vector)
 
             t_2 = t_1.take_start 2
-            t_2.index.to_vector . should_equal (t_1.index.to_vector . take_start 2)
+            t_2.index.to_vector . should_equal (t_1.index.to_vector . take (First 2))
-            t_2.at 'col' . to_vector . should_equal (t_1.at 'col' . to_vector . take_start 2)
+            t_2.at 'col' . to_vector . should_equal (t_1.at 'col' . to_vector . take (First 2))
-            t_2.at 'col2' . to_vector . should_equal (t_1.at 'col2' . to_vector . take_start 2)
+            t_2.at 'col2' . to_vector . should_equal (t_1.at 'col2' . to_vector . take (First 2))
-            t_2.at 'col3' . to_vector . should_equal (t_1.at 'col3' . to_vector . take_start 2)
+            t_2.at 'col3' . to_vector . should_equal (t_1.at 'col3' . to_vector . take (First 2))
 
-            t_1.at 'col' . take_start 2 . to_vector . should_equal (t_1.at 'col' . to_vector . take_start 2)
+            t_1.at 'col' . take_start 2 . to_vector . should_equal (t_1.at 'col' . to_vector . take (First 2))
 
         Test.specify "should allow taking the last n rows" <|
             i_1 = ['ix', [1, 2, 3]]
@@ -503,10 +503,10 @@ spec =
             t_1.take_end 10 . at 'col1' . to_vector . should_equal (t_1.at 'col1' . to_vector)
 
             t_2 = t_1.take_end 2
-            t_2.index.to_vector . should_equal (t_1.index.to_vector . take_end 2)
+            t_2.index.to_vector . should_equal (t_1.index.to_vector . take (Last 2))
-            t_2.at 'col1' . to_vector . should_equal (t_1.at 'col1' . to_vector . take_end 2)
+            t_2.at 'col1' . to_vector . should_equal (t_1.at 'col1' . to_vector . take (Last 2))
-            t_2.at 'col2' . to_vector . should_equal (t_1.at 'col2' . to_vector . take_end 2)
+            t_2.at 'col2' . to_vector . should_equal (t_1.at 'col2' . to_vector . take (Last 2))
-            t_2.at 'col3' . to_vector . should_equal (t_1.at 'col3' . to_vector . take_end 2)
+            t_2.at 'col3' . to_vector . should_equal (t_1.at 'col3' . to_vector . take (Last 2))
 
         Test.specify "should allow getting the first / head row" <|
             i_1 = ['ix', [1, 2, 3]]

test/Tests/src/Data/Range_Spec.enso

@@ -77,6 +77,16 @@ spec = Test.group "Range" <|
             x = cell.get
             cell.put x+1
         cell.get . should_equal n
+    Test.specify "should allow iteration with index" <|
+        vec_mut = Vector.new_builder
+        5.up_to 8 . each_with_index ix-> elem->
+            vec_mut.append (Pair ix elem)
+        vec_mut.to_vector . should_equal [Pair 0 5, Pair 1 6, Pair 2 7]
+
+        vec_mut_2 = Vector.new_builder
+        5.up_to 10 . with_step 2 . each_with_index ix-> elem->
+            vec_mut_2.append (Pair ix elem)
+        vec_mut_2.to_vector . should_equal [Pair 0 5, Pair 1 7, Pair 2 9]
     Test.specify "should be able to be folded" <|
         1.up_to 6 . fold 0 (+) . should_equal 15
     Test.specify "should check all" <|

test/Tests/src/Data/Text/Default_Regex_Engine_Spec.enso

@@ -8,10 +8,6 @@ polyglot java import java.util.regex.Pattern as Java_Pattern
 
 import Standard.Test
 
-Text.slice_utf_16 self start end =
-    chars = self.utf_16.drop_start start . drop_end (self.length - end)
-    Text.from_utf_16 chars
-
 default_mask = Java_Pattern.CANON_EQ.bit_or Java_Pattern.UNICODE_CASE . bit_or Java_Pattern.UNICODE_CHARACTER_CLASS
 
 spec =

test/Tests/src/Data/Text/Text_Sub_Range_Spec.enso

@@ -4,21 +4,23 @@ from Standard.Base.Data.Text.Text_Sub_Range import all
 
 import Standard.Test
 
-spec = Test.group "Text_Sub_Range.Codepoint_Ranges" <|
+spec = Test.group "Text_Sub_Range" <|
-    run ranges =
+    Test.specify "should correctly split a text into grapheme cluster ranges expressed in codepoint indices" <|
-        Codepoint_Ranges ranges False . sorted_and_distinct_ranges
+        character_ranges "" . should_equal []
-    Test.specify "should be able to sort correctly merge neighboring sequences" <|
+        character_ranges "A" . should_equal [Range 0 1]
-        run [] . should_equal []
+        character_ranges "abc" . should_equal [Range 0 1, Range 1 2, Range 2 3]
-        run [Range 0 0] . should_equal []
+        character_ranges 'śs\u0301S' . should_equal [Range 0 1, Range 1 3, Range 3 4]
-        run [Range 0 10] . should_equal [Range 0 10]
+
-        run [Range 0 10, Range 2 4] . should_equal [Range 0 10]
+        kshi = '\u0915\u094D\u0937\u093F'
-        run [Range 0 5, Range 5 10] . should_equal [Range 0 10]
+        facepalm = '\u{1F926}\u{1F3FC}\u200D\u2642\uFE0F'
-        run [Range 5 10, Range 0 0, Range 0 1, Range 1 5] . should_equal [Range 0 10]
+        accent_1 = '\u00E9'
-        run [Range 0 1, Range 1 2] . should_equal [Range 0 2]
+        accent_2 = '\u0065\u{301}'
-        run [Range 6 7, Range 7 8, Range 5 5, Range 0 1, Range 2 3] . should_equal [Range 0 1, Range 2 3, Range 6 8]
+        character_ranges kshi . should_equal [Range 0 4]
-        run [Range 5 10, Range 3 6, Range 3 6, Range 3 5, Range 3 7, Range 0 1] . should_equal [Range 0 1, Range 3 10]
+        character_ranges facepalm . should_equal [Range 0 7]
-        run [Range 0 1, Range 0 1] . should_equal [Range 0 1]
+        character_ranges accent_1 . should_equal [Range 0 1]
-        run [Range 0 1, Range 1 2] . should_equal [Range 0 2]
+        character_ranges accent_2 . should_equal [Range 0 2]
+        character_ranges kshi+facepalm+accent_1+accent_2 . should_equal [Range 0 4, Range 4 11, Range 11 12, Range 12 14]
+
     Test.specify "should correctly split a text into grapheme cluster ranges expressed in codepoint indices" <|
         character_ranges "" . should_equal []
         character_ranges "A" . should_equal [Range 0 1]

test/Tests/src/Data/Text_Spec.enso

@@ -4,6 +4,7 @@ from Standard.Base.Data.Text.Extensions import Index_Out_Of_Bounds_Error
 import Standard.Base.Data.Text.Regex.Engine.Default as Default_Engine
 
 from Standard.Base.Data.Text.Text_Sub_Range import all
+from Standard.Base.Data.Index_Sub_Range import First, Last, While, By_Index, Sample, Every
 
 import Standard.Test
 
@@ -262,7 +263,7 @@ spec =
             "ABCDEFGH".drop (Every 3 first=1) . should_equal "ACDFG"
             "ABCDEFGHI".drop (Every 3 first=1) . should_equal "ACDFGI"
 
-        Test.specify "should allow selecting a random sample of a substring"
+        Test.specify "should allow taking or dropping a random sample of a substring"
             "AAAAA".take (Sample 3) . should_equal "AAA"
             "AAAAA".drop (Sample 3) . should_equal "AA"
 
@@ -275,6 +276,10 @@ spec =
             "ABCDEFGH".take (Sample 1 seed=42) . should_equal "F"
             "ABCDEFGH".take (Sample 100 seed=42) . should_equal "FGCHABED"
 
+            samples_1 = 0.up_to 10000 . map seed->
+                "ABCD".take (Sample 2 seed)
+            samples_1.should_contain_the_same_elements_as ["AB", "BA", "AC", "CA", "AD", "DA", "BC", "CB", "BD", "DB", "CD", "DC"]
+
             "ABCDEFGH".drop (Sample 0) . should_equal "ABCDEFGH"
             "ABCDEFGH".drop (Sample 1 seed=42) . should_equal "ABCDEGH"
             "ABCDEFGH".drop (Sample 2 seed=42) . should_equal "ABCDEH"
@@ -282,6 +287,10 @@ spec =
             "ABCDEFGH".drop (Sample 8 seed=42) . should_equal ""
             "ABCDEFGH".drop (Sample 100 seed=42) . should_equal ""
 
+            samples_2 = 0.up_to 10000 . map seed->
+                "ABCD".drop (Sample 2 seed)
+            samples_2.should_contain_the_same_elements_as ["AB", "AC", "AD", "BC", "CD", "BD"]
+
         Test.specify "should allow taking or dropping many indices or subranges (possibly overlapping)" <|
             "123"*1000 . take (By_Index (Vector.new 3000 ix-> 2999-ix)) . should_equal "321"*1000
             "123"*1000 . take (By_Index (Vector.new 3000 _-> 0)) . should_equal "1"*3000

test/Tests/src/Data/Vector/Slicing_Helpers_Spec.enso

@@ -0,0 +1,20 @@
+from Standard.Base import all
+
+import Standard.Test
+
+spec = Test.group "Vector Slicing Helpers" <|
+    Test.specify "should be able to sort correctly merge neighboring sequences" <|
+        merge = Vector.sort_and_merge_ranges
+        merge [] . should_equal []
+        merge [Range 0 0] . should_equal []
+        merge [Range 0 10] . should_equal [Range 0 10]
+        merge [Range 0 10, Range 2 4] . should_equal [Range 0 10]
+        merge [Range 0 5, Range 5 10] . should_equal [Range 0 10]
+        merge [Range 5 10, Range 0 0, Range 0 1, Range 1 5] . should_equal [Range 0 10]
+        merge [Range 0 1, Range 1 2] . should_equal [Range 0 2]
+        merge [Range 6 7, Range 7 8, Range 5 5, Range 0 1, Range 2 3] . should_equal [Range 0 1, Range 2 3, Range 6 8]
+        merge [Range 5 10, Range 3 6, Range 3 6, Range 3 5, Range 3 7, Range 0 1] . should_equal [Range 0 1, Range 3 10]
+        merge [Range 0 1, Range 0 1] . should_equal [Range 0 1]
+        merge [Range 0 1, Range 1 2] . should_equal [Range 0 2]
+
+main = Test.Suite.run_main spec

test/Tests/src/Data/Vector_Spec.enso

@@ -1,4 +1,5 @@
 from Standard.Base import all
+from Standard.Base.Data.Index_Sub_Range import While, By_Index, Sample, Every
 
 import Standard.Test
 
@@ -189,15 +190,110 @@ spec = Test.group "Vectors" <|
         vec = [1, 2, 3, 4, 5, 6]
         first_four = [1, 2, 3, 4]
         last_four = [3, 4, 5, 6]
-        vec.take 2 4 . should_equal [3, 4]
-        vec.drop_start 2 . should_equal last_four
-        vec.drop_end 2 . should_equal first_four
-        vec.take_start 4 . should_equal first_four
-        vec.take_end 4 . should_equal last_four
 
-        [1, 3, 5, 6, 8, 9, 10, 11, 13].drop_while (x-> x%2 == 1) . should_equal [6, 8, 9, 10, 11, 13]
+        vec.take . should_equal [1]
-        [1, 2, 3] . drop_while (_ > 10) . should_equal [1, 2, 3]
+        vec.drop . should_equal [2, 3, 4, 5, 6]
-        [1, 2, 3] . drop_while (_ < 10) . should_equal []
+
+        vec.take (Range 2 4) . should_equal [3, 4]
+        vec.take (Range 0 0) . should_equal []
+        vec.take (Range 100 100) . should_fail_with Index_Out_Of_Bounds_Error
+        vec.take (Range 100 100) . catch . should_equal (Index_Out_Of_Bounds_Error 100 6)
+        vec.take (Range 0 100) . should_equal vec
+        [].take (Range 0 0) . should_fail_with Index_Out_Of_Bounds_Error
+        [].take (Range 0 0) . catch . should_equal (Index_Out_Of_Bounds_Error 0 0)
+        vec.take (Range 100 99) . should_fail_with Index_Out_Of_Bounds_Error
+
+        vec.drop (Range 2 4) . should_equal [1, 2, 5, 6]
+        vec.drop (Range 0 0) . should_equal vec
+        vec.drop (Range 100 100) . should_fail_with Index_Out_Of_Bounds_Error
+        vec.drop (Range 100 100) . catch . should_equal (Index_Out_Of_Bounds_Error 100 6)
+        vec.drop (Range 0 100) . should_equal []
+        [].drop (Range 0 0) . should_fail_with Index_Out_Of_Bounds_Error
+        [].drop (Range 0 0) . catch . should_equal (Index_Out_Of_Bounds_Error 0 0)
+        vec.drop (Range 100 99) . should_fail_with Index_Out_Of_Bounds_Error
+
+        vec.take (First 4) . should_equal first_four
+        vec.take (First 0) . should_equal []
+        vec.take (First -1) . should_equal []
+        vec.take (First 100) . should_equal vec
+
+        vec.drop (First 2) . should_equal last_four
+        vec.drop (First 0) . should_equal vec
+        vec.drop (First -1) . should_equal vec
+        vec.drop (First 100) . should_equal []
+
+        vec.take (Last 4) . should_equal last_four
+        vec.take (Last 0) . should_equal []
+        vec.take (Last -1) . should_equal []
+        vec.take (Last 100) . should_equal vec
+
+        vec.drop (Last 2) . should_equal first_four
+        vec.drop (Last 0) . should_equal vec
+        vec.drop (Last -1) . should_equal vec
+        vec.drop (Last 100) . should_equal []
+
+        vec.take (Every 3) . should_equal [1, 4]
+        vec.take (Every 3 first=1) . should_equal [2, 5]
+        vec.take (Every 2 first=1) . should_equal [2, 4, 6]
+        vec.take (Every 2 first=100) . should_equal []
+        vec.take (Every 200) . should_equal [1]
+        [].take (Every 2) . should_equal []
+        vec.take (Every 0) . should_fail_with Illegal_Argument_Error
+        [].take (Every 0) . should_fail_with Illegal_Argument_Error
+
+        vec.drop (Every 3) . should_equal [2, 3, 5, 6]
+        vec.drop (Every 3 first=1) . should_equal [1, 3, 4, 6]
+        vec.drop (Every 2 first=1) . should_equal [1, 3, 5]
+        vec.drop (Every 2 first=100) . should_equal vec
+        vec.drop (Every 200) . should_equal [2, 3, 4, 5, 6]
+        [].drop (Every 2) . should_equal []
+        vec.drop (Every 0) . should_fail_with Illegal_Argument_Error
+        [].drop (Every 0) . should_fail_with Illegal_Argument_Error
+
+        vec.take (By_Index 0) . should_equal [1]
+        [].take (By_Index 0) . should_fail_with Index_Out_Of_Bounds_Error
+        vec.take (By_Index []) . should_equal []
+        vec.take (By_Index [-1, -1]) . should_equal [6, 6]
+        vec.take (By_Index [0, 0, Range 3 100]) . should_equal [1, 1, 4, 5, 6]
+        vec.take (Range 0 100 2) . should_equal [1, 3, 5]
+        vec.take (By_Index [Range 0 100 2, Range 1 6 2]) . should_equal [1, 3, 5, 2, 4, 6]
+        vec.take (By_Index [Range 1 3, Range 2 5]) . should_equal [2, 3, 3, 4, 5]
+        vec.take (By_Index [Range 2 5, Range 1 3]) . should_equal [3, 4, 5, 2, 3]
+        vec.take (By_Index [0, 1, Range 100 200]) . should_fail_with Index_Out_Of_Bounds_Error
+        vec.take (By_Index 100) . should_fail_with Index_Out_Of_Bounds_Error
+
+        vec.drop (By_Index 0) . should_equal [2, 3, 4, 5, 6]
+        vec.drop (By_Index []) . should_equal vec
+        vec.drop (By_Index [-1, -1]) . should_equal [1, 2, 3, 4, 5]
+        vec.drop (By_Index [0, 0, Range 3 100]) . should_equal [2, 3]
+        vec.drop (Range 0 100 2) . should_equal [2, 4, 6]
+        vec.drop (By_Index [Range 0 100 2, Range 1 6 2]) . should_equal []
+        vec.drop (By_Index [Range 1 3, Range 2 5]) . should_equal [1, 6]
+        vec.drop (By_Index [Range 2 5, Range 1 3]) . should_equal [1, 6]
+        vec.drop (By_Index [0, 1, Range 100 200]) . should_fail_with Index_Out_Of_Bounds_Error
+        vec.drop (By_Index 100) . should_fail_with Index_Out_Of_Bounds_Error
+
+        [1, 3, 5, 6, 8, 9, 10, 11, 13].take (While (x-> x%2 == 1)) . should_equal [1, 3, 5]
+        [1, 2, 3] . take (While (_ > 10)) . should_equal []
+        [1, 2, 3] . take (While (_ < 10)) . should_equal [1, 2, 3]
+
+        [1, 3, 5, 6, 8, 9, 10, 11, 13].drop (While (x-> x%2 == 1)) . should_equal [6, 8, 9, 10, 11, 13]
+        [1, 2, 3] . drop (While (_ > 10)) . should_equal [1, 2, 3]
+        [1, 2, 3] . drop (While (_ < 10)) . should_equal []
+
+        vec.take (Sample 0) . should_equal []
+        [].take (Sample 0) . should_equal []
+        [].take (Sample 1) . should_equal []
+        ["a"].take (Sample 1) . should_equal ["a"]
+        ["a", "a", "a"].take (Sample 1) . should_equal ["a"]
+        ["a", "a", "a"].take (Sample 100) . should_equal ["a", "a", "a"]
+
+        vec.drop (Sample 0) . should_equal vec
+        [].drop (Sample 0) . should_equal []
+        [].drop (Sample 1) . should_equal []
+        ["a"].drop (Sample 1) . should_equal []
+        ["a", "a", "a"].drop (Sample 1) . should_equal ["a", "a"]
+        ["a", "a", "a"].drop (Sample 100) . should_equal []
 
     Test.specify "should allow getting the head element" <|
         non_empty_vec = [1, 2, 3, 4, 5]

test/Tests/src/Main.enso

@@ -42,7 +42,7 @@ import project.Data.Statistics_Spec
 import project.Data.Regression_Spec
 
 import project.Data.Text_Spec
-import project.Data.Text.Codepoint_Ranges_Spec
+import project.Data.Text.Text_Sub_Range_Spec
 import project.Data.Text.Default_Regex_Engine_Spec
 import project.Data.Text.Encoding_Spec
 import project.Data.Text.Matching_Spec
@@ -50,6 +50,8 @@ import project.Data.Text.Regex_Spec
 import project.Data.Text.Span_Spec
 import project.Data.Text.Utils_Spec
 
+import project.Data.Vector.Slicing_Helpers_Spec
+
 import project.Network.Http.Header_Spec as Http_Header_Spec
 import project.Network.Http.Request_Spec as Http_Request_Spec
 import project.Network.Http_Spec
@@ -114,7 +116,7 @@ main = Test.Suite.run_main <|
     Runtime_Spec.spec
     Span_Spec.spec
     Encoding_Spec.spec
-    Codepoint_Ranges_Spec.spec
+    Text_Sub_Range_Spec.spec
     Bracket_Spec.spec
     Lazy_Generator_Spec.spec
     Stack_Traces_Spec.spec
@@ -123,6 +125,7 @@ main = Test.Suite.run_main <|
     Time_Spec.spec
     URI_Spec.spec
     Vector_Spec.spec
+    Slicing_Helpers_Spec.spec
     Statistics_Spec.spec
     Regression_Spec.spec
     Warnings_Spec.spec

test/Tests/src/Random_Spec.enso

@@ -25,6 +25,11 @@ spec = Test.group "Random" <|
         Random.random_indices 1 100 rng . should_equal [0]
         Random.random_indices 100 0 rng . should_equal []
 
+        two_out_of_four = 0.up_to 10000 . map seed->
+            Random.random_indices 4 2 (Random.new seed)
+        two_out_of_four . should_contain_the_same_elements_as <|
+            [[0, 1], [0, 2], [1, 2], [1, 0], [2, 0], [2, 1], [0, 3], [1, 3], [2, 3], [3, 0], [3, 1], [3, 2]]
+
     Test.specify "should allow to select a random sample from a vector" <|
         rng = Random.new 0
         vector = ["A", "B", "C"]

test/Tests/src/Runtime/Stack_Traces_Spec.enso

@@ -15,7 +15,7 @@ spec = Test.group "Stack traces" <|
         modname = Meta.Constructor (Meta.meta Stack_Traces_Spec . constructor) . name
         stack = My_Type.foo
         names = [modname + ".bar", modname + ".baz", "Number.foo", modname + ".foo", "My_Type.foo"]
-        stack.take_start 5 . map .name . should_equal names
+        stack.take (First 5) . map .name . should_equal names
         file = enso_project.root / 'src' / 'Runtime' / 'Stack_Traces_Spec.enso'
-        stack.take_start 5 . map (.source_location >> .file) . each (_.should_equal file)
+        stack.take (First 5) . map (.source_location >> .file) . each (_.should_equal file)
 

test/Tests/src/Semantic/Warnings_Spec.enso

@@ -107,7 +107,7 @@ spec = Test.group "Dataflow Warnings" <|
         current = Runtime.get_stack_trace
         warned = foo "value"
         warning_stack = Warning.get_all warned . head . origin
-        relevant = warning_stack . drop_end current.length
+        relevant = warning_stack . drop (Last current.length)
         relevant.map .name . should_equal (['baz', 'bar', 'foo'].map ('Warnings_Spec.'+))
 
     Test.specify "should attach reassignment info in the last-reassigned-first order" <|

test/Tests/src/System/File_Spec.enso

@@ -84,12 +84,12 @@ spec =
     Test.group "read_bytes" <|
         Test.specify "should allow reading a file to byte vector" <|
             contents = sample_file.read_bytes
-            contents.take_start 6 . should_equal [67, 117, 112, 99, 97, 107]
+            contents.take (First 6) . should_equal [67, 117, 112, 99, 97, 107]
 
         Test.specify "should allow reading a file to byte vector via path" <|
             full_path = sample_file . path
             contents = File.read_bytes full_path
-            contents.take_start 6 . should_equal [67, 117, 112, 99, 97, 107]
+            contents.take (First 6) . should_equal [67, 117, 112, 99, 97, 107]
 
         Test.specify "should allow to read last n bytes from a file" <|
             file = enso_project.data / "transient" / "bytes.txt"
@@ -111,10 +111,10 @@ spec =
         Test.specify "should open and read the file in one shot" <|
             path_name = sample_file.path
             contents = File.read_bytes path_name
-            contents.take_start 6 . should_equal [67, 117, 112, 99, 97, 107]
+            contents.take (First 6) . should_equal [67, 117, 112, 99, 97, 107]
             file = sample_file
             contents_2 = File.read_bytes file
-            contents_2.take_start 6 . should_equal [67, 117, 112, 99, 97, 107]
+            contents_2.take (First 6) . should_equal [67, 117, 112, 99, 97, 107]
 
     Test.group "read_text" <|
         Test.specify "should allow reading a UTF-8 file" <|