Proposal: take, skip LINQ query clauses

[orthoxerox]

Similar to #94, but covers more methods.

A query expression with a take clause

from x in e
take e2
…

is translated into

from x in ( e ) . Take ( e2 )
…

A query expression with a skip clause

from x in e
skip e2
…

is translated into

from x in ( e ) . Skip ( e2 )
…

A query expression with a take while clause

from x in e
take while f
…

is translated into

from x in ( e ) . TakeWhile ( x => f )
…

A query expression with a skip while clause

from x in e
skip while f
…

is translated into

from x in ( e ) . SkipWhile ( x => f )
…

A query expression with a take until clause

from x in e
take until f
…

is translated into

from x in ( e ) . TakeWhile ( x => ! ( f ) )
…

A query expression with a skip until clause

from x in e
skip until f
…

is translated into

from x in ( e ) . SkipWhile ( x => ! ( f ) )
…

[HaloFour]

VB.NET already has some of these LINQ query clauses. Specifically Take, Take While, Skip and Skip While. Interestingly VB.NET does not have Take Until or Skip Until despite already having Until as a keyword for Do loops. I'd assume that adding it to C# might depend on whether or not until was also added as a contextual keyword for loops.

Even if a general purpose continuable clause is added to the language I still think it's worth adding specific clauses to handle these really common cases.

[tuespetre]

Loving this proposal except I have to say that I would prefer take while and skip while over take until and skip until. I think consistency is important, plus it wouldn't need a new keyword.

[orthoxerox]

Prototype being developed in https://github.com/orthoxerox/roslyn/tree/features/linq-take-skip

[scalablecory]

See also dotnet/roslyn#100

[lcsondes]

take and skip in particular have widespread support in SQL (through LIMIT and depending on the dialect, OFFSET) and are very commonly used, e.g., for pagination in backend code.