A mapping of the feature set of the LINQ API to D's Range API.

Filtering

LINQ	D
Where	filter
OfTyp	castSwitch

Projections

LINQ	D
Select	map
SelectMany	=
Anonoymous Types	Tuples
Indexed	enumerate

from c in customers
from o in c.Orders
where c.Region == "WA"

Partitioning

LINQ	D
Take	take
Skip	drop
TakeWhile	until
SkipWhile	find

Ordering

LINQ	D
OrderBy	sort
OrderBy + Comparer	sort + opCmp
OrderByDescending	sort
OrderByDescending + Comparer	sort + opCmp
ThenBy	multiSort
ThenBy + Comparer	multiSort + opCmp
ThenByDescending	multiSort
ThenByDescending + Comparer	multiSort + opCmp
Reverse	retro

Grouping

LINQ	D
GroupBy	chunkBy, group
GroupJoin

Grouping: https://msdn.microsoft.com/en-us/library/mt693097.aspx

Set operators

LINQ	D
Distinct	uniq
Union	merge
Intersect	setIntersection
Except	setDifference

D expects sortedness of all inputs.

Conversion

LINQ	D
ToArray	array
ToList	array
ToDictionary	assocArray
ToLookup	chunkby.assocArray
Cast	no need (universal API)
AsQueryable	isInputRange
AsEnumerable	isRandomAccessRange
OfType	typeof

Element operators

LINQ	D
First	front
FirstOrDefault	r.empty ? "default" : r.front
ElementAt	[[]]
ElementAtOrDefault	i < r.length ? "default" : r[i]
Last	back
LastOrDefault	r.empty ? "default" : r.front
Single	r.length == 1 ? r.front : throw new Exception("Range is supposed to contain a single value only")
SingleOrDefault	r.length <= 1 ? (r.empty ? "default" : r.front ) : throw new Exception("Range is supposed to contain a single value only")

Generation operators

LINQ	D
Range	iota
Repeat	repeat
Empty	empty
DefaultIfEmpty	r.empty ? "default" : r.front

Quantifiers

LINQ	D
Any	any
All	all
Contains	find, canFind

Aggregate

LINQ	D
Count	length if RandomAccess, otherwise walkLength
Sum	sum
Min	minElement
Max	maxElement
Average
Aggregate	reduce
LongCount	length / walkLength use size_t

Equality

LINQ	D
SequenceEqual	equal

Concatenation

LINQ	D
Concat	chain

Query execution

LINQ	D
Deferred Execution	Ranges in D are lazy
Immediate Execution	e.g. each
Query Reuse	save
Custom generator	generate

Joins

• Cross Join
• Group Join
• Cross Join with Group Join
• Left Outer Join

https://msdn.microsoft.com/en-us/library/mt693045.aspx