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Minor optimizations for Range.shift/2 #14724

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Merged
merged 3 commits into from
Aug 28, 2025
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Minor optimizations for Range.shift/2 #14724

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66c3f11
Minor optimizations for `Range.shift/2`
eksperimental Aug 28, 2025
f9cb623
Remove unnecessary function head in `Range.shift/2`
eksperimental Aug 28, 2025
33ce63f
Update lib/elixir/lib/range.ex
eksperimental Aug 28, 2025
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11 changes: 8 additions & 3 deletions lib/elixir/lib/range.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -290,9 +290,14 @@ defmodule Range do
"""
@doc since: "1.14.0"
@spec shift(t, integer) :: t
def shift(first..last//step, steps_to_shift)
when is_integer(steps_to_shift) do
new(first + steps_to_shift * step, last + steps_to_shift * step, step)
def shift(range, steps_to_shift)

def shift(range, 0) when is_struct(range, Range), do: range
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Suggested change
def shift(range, 0) when is_struct(range, Range), do: range
def shift(%Range{} = range, 0), do: range

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@josevalim I wanted to ask you if there's any performance difference doing pattern matches vs is_struct/2? Or it is just a matter of style.
Personally I favor the is_struct/2 approach as it declutter the function arguments section a bit.


def shift(first..last//step, steps_to_shift) when is_integer(steps_to_shift) do
shift = steps_to_shift * step

new(first + shift, last + shift, step)
end

@doc """
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1 change: 1 addition & 0 deletions lib/elixir/test/elixir/range_test.exs
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Expand Up @@ -60,6 +60,7 @@ defmodule RangeTest do

test "shift" do
assert Range.shift(0..10//2, 2) == 4..14//2
assert Range.shift(0..10//2, 0) == 0..10//2
assert Range.shift(10..0//-2, 2) == 6..-4//-2
assert Range.shift(10..0//-2, -2) == 14..4//-2
end
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