Commit781b410

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Optimize truncate for n = 0 (#5099)

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Lines changed: 7 additions & 6 deletions

Original file line number	Diff line number	Diff line change
`@@ -756,12 +756,13 @@ module internal List =`
`756`	`756`	`truncateToFreshConsTail cons2(count-1) t`
`757`	`757`
`758`	`758`	`lettruncate count list=`
`759`		`-match listwith`
`760`		`-\|[]-> list`
`761`		`-\|_::([]as nil)->if count>0then listelse nil`
`762`		`-\| h::t->`
`763`		`-if count<=0then[]`
`764`		`-else`
	`759`	`+if count<=0then`
	`760`	`+[]`
	`761`	`+else`
	`762`	`+match listwith`
	`763`	`+\|[]`
	`764`	`+\|[_]-> list`
	`765`	`+\| h::t->`
`765`	`766`	`letcons= freshConsNoTail h`
`766`	`767`	`truncateToFreshConsTail cons(count-1) t`
`767`	`768`	`cons`

Lines changed: 1 addition & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -852,6 +852,7 @@ namespace Microsoft.FSharp.Collections`
`852`	`852`	`[<CompiledName("Truncate")>]`
`853`	`853`	`lettruncate count(source:seq<'T>)=`
`854`	`854`	`checkNonNull"source" source`
	`855`	`+if count<=0then emptyelse`
`855`	`856`	`seq{leti= ref0`
`856`	`857`	`use ie= source.GetEnumerator()`
`857`	`858`	`while!i< count&& ie.MoveNext()do`

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