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2021 January 01
RM
активный
SB
ID:0
На фримонадах это самый кровопролитный способ, особенно в языках, которые не предоставляют аналог do-нотации Хаскеля.
2021 January 02
2021 January 03
MM
Dear all,
I have an issue about using
When I run, here is the result:
Sorry for my english.
🙂
How do I fix this?
I have an issue about using
F# with linq.open System
type MyTags = List<string>
type MySong = { Title: string; Tags: Option<MyTags> }
let songs : List<MySong> = [
{ Title = "Cantaloupe Island";
Tags = Some ["60s"; "jazz"]};
{ Title = "Let It Be";
Tags = Some ["60s"; "rock"]};
{ Title = "Knockin' on Heaven's Door";
Tags = Some ["70s"; "rock"]};
{ Title = "Emotion";
Tags = Some ["70s"; "pop"]};
{ Title = "The River";
Tags = None};
]
let extractTagss songs =
query {
for song in songs do
where (song.Tags <> None)
select song.Tags
} |> Seq.toList
[<EntryPoint>]
for tags in (songs |> extractTagss) do
tags |> Console.WriteLine
When I run, here is the result:
$ dotnet fsi 14-linq.fsx
/home/epsi/Documents/songs/fsharp/14-linq.fsx(27,23): error FS0001: The type 'List<MySong>' is not compatible with the type 'Linq.IQueryable<MySong>'
Sorry for my english.
🙂
How do I fix this?
AH
Dear all,
I have an issue about using
When I run, here is the result:
Sorry for my english.
🙂
How do I fix this?
I have an issue about using
F# with linq.open System
type MyTags = List<string>
type MySong = { Title: string; Tags: Option<MyTags> }
let songs : List<MySong> = [
{ Title = "Cantaloupe Island";
Tags = Some ["60s"; "jazz"]};
{ Title = "Let It Be";
Tags = Some ["60s"; "rock"]};
{ Title = "Knockin' on Heaven's Door";
Tags = Some ["70s"; "rock"]};
{ Title = "Emotion";
Tags = Some ["70s"; "pop"]};
{ Title = "The River";
Tags = None};
]
let extractTagss songs =
query {
for song in songs do
where (song.Tags <> None)
select song.Tags
} |> Seq.toList
[<EntryPoint>]
for tags in (songs |> extractTagss) do
tags |> Console.WriteLine
When I run, here is the result:
$ dotnet fsi 14-linq.fsx
/home/epsi/Documents/songs/fsharp/14-linq.fsx(27,23): error FS0001: The type 'List<MySong>' is not compatible with the type 'Linq.IQueryable<MySong>'
Sorry for my english.
🙂
How do I fix this?
Not sure, but seems you can't use list as data source for query builder.
MM
Not sure, but seems you can't use list as data source for query builder.
What simple data can I use for query builder?
AH
What simple data can I use for query builder?
Do you need query builder at all?
If you really need it, I think you should explicitly cast List to IQueryable
If you really need it, I think you should explicitly cast List to IQueryable
MM
Do you need query builder at all?
If you really need it, I think you should explicitly cast List to IQueryable
If you really need it, I think you should explicitly cast List to IQueryable
Wait...
I will response in an hour.
I will response in an hour.
PD
List doesn't implement IQueryable. So you should cast it using the extensions method
.AsQueryable() (from the System.Linq namespace)MM
List doesn't implement IQueryable. So you should cast it using the extensions method
.AsQueryable() (from the System.Linq namespace)That's working. Awesomeee 🙏🏽.
YT
Што
YT
Это правда?
SN
Это правда?
no
YT
Фух
SN
оно так начиналось
