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remove outdated performance comments

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Brendan Hansknecht 2023-03-12 11:27:55 -07:00
parent dfb748fb03
commit 5d87ba3441
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19
crates/compiler/builtins/roc/List.roc
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@ -846,15 +846,6 @@ dropLast = \list ->
##
## To split the list into two lists, use `List.split`.
##
## ## Performance Details
##
## When given a Unique list, this runs extremely fast. It sets the list's length
## to the given length value, and frees the leftover elements. This runs very
## slightly faster than `List.takeLast`.
##
## In fact, `List.takeFirst list 1` runs faster than `List.first list` when given
## a Unique list, because [List.first] returns the first element as well -
## which introduces a conditional bounds check as well as a memory load.
takeFirst : List elem, Nat -> List elem
takeFirst = \list, outputLength ->
List.sublist list { start: 0, len: outputLength }
@ -875,16 +866,6 @@ takeFirst = \list, outputLength ->
##
## To split the list into two lists, use `List.split`.
##
## ## Performance Details
##
## When given a Unique list, this runs extremely fast. It moves the list's
## pointer to the index at the given length value, updates its length,
## and frees the leftover elements. This runs very nearly as fast as
## `List.takeFirst` on a Unique list.
##
## In fact, `List.takeLast list 1` runs faster than `List.first list` when given
## a Unique list, because [List.first] returns the first element as well -
## which introduces a conditional bounds check as well as a memory load.
takeLast : List elem, Nat -> List elem
takeLast = \list, outputLength ->
List.sublist list { start: Num.subSaturated (List.len list) outputLength, len: outputLength }