F# List SelectMany
- by Tuomas Hietanen
This is quite simple question but I didn't find an answer:
Is there any Seq/List operation in F# to match the LINQ SelectMany?
I know I can use System.Linq in F# if I
want to.
I know I can make a recursive method
and use F# Computation Expressions
(and make even more powerful things).
But if I try to prove that F# List operations are more powerful than LINQ...
.Where = List.filter
.Select = List.map
.Aggregate = List.fold
...
In C# SelectMany usage syntax is pretty simple:
var flattenedList = from i in items1
from j in items2
select ...
Is there any easy direct match, List.flatten, List.bind or something like that?
SelectMany has a couple of signatures, but the most complex one seems to be:
IEnumerable<TResult> SelectMany<TSource, TCollection, TResult>(
this IEnumerable<TSource> source,
Func<TSource, IEnumerable<TCollection>> collectionSelector,
Func<TSource, TCollection, TResult> resultSelector
);
In F# terms this would be:
('a -> 'b list) -> ('a -> 'b -> 'c) -> 'a list -> 'c list
