Sometimes, when you feel really alone and want a bit of heat then F# can help you here.
All you need is a laptop and F#. Just type the following snippet into FSI and wait for a minute. =)
[|1..999|] |> Array.Parallel.iter (fun _ ->
while true do ignore())
Wish you warm Christmas!
P.S. The same solution works when you are freezing.
this is really cool 🙂
Can you help to write efficient code in F# to achieve following.
— connect to database and get dataset
— prepare my object (i.e Person(){firstname, lastname) from this data and create a List of Person object.
— Now whenever I need to access person details i read it from this collection. No more calls to database
In My code i have achieved to do all of them except the last point. Every time i access Person object its going to database and reload the data 😦
thanks in advance. is there any personal email address from you so i can contact you about some of the implementation in F# i am working on
many thanks in advance 🙂
It is really depend on the database that you use. If you use SQL for example, you should use SqlTypeProvider. If you use Mongo, then Fsharp.Mongo will be good choice. Please share a bit more details.
BTW. StackOverflow http://stackoverflow.com/questions/tagged/f%23 is great place for questions, there are lot of experts there.
Reblogged this on D Says and commented:
This is a real fun and let your frustration go out from your computer.
thanks for the reply . Here is my code below.
module sql
open System
open System.Collections.Generic
open System.Data
open System.Data.SqlClient
open System.Reflection
open System.Data.OleDb;
open System.Text.RegularExpressions
open Microsoft.FSharp.Reflection
// Using records to store the data
type Person = { FirstName:string; LastName:string; Age:int }
let connectionString= “myDBConnectionstring”
// Runs the specified query ‘sql’ and formats rows using function ‘f’
let query sql f =
seq { use cn = new SqlConnection(connectionString) // will be disposed
let da = new SqlDataAdapter(new SqlCommand(sql, cn))
let ds = new DataSet()
cn.Open()
let i = da.Fill(ds)
let rowCol = ds.Tables.[0].Rows
for i in 0 .. (10 – 1) do // just take 10 records for test
yield f (rowCol.[i]) }
let names = query “SELECT * FROM User_tbl” (fun row -> row.[“FirstName”])
for name in names do printfn “%A” name
names |> Seq.iter (printfn “%A”)
Now when i access objects from “names” than its accessing the database (which i understand why as my code is written like this )
i want to load it once only.
It is happened because the sequence is lazy. Please try to load it into list or array, like this
let names = query “SELECT * FROM User_tbl” (fun row -> row.[“FirstName”]) |> Seq.toArray
But, much shorter code will be with TypeProviders
http://msdn.microsoft.com/en-us/library/hh361033.aspx
Hello
Is there something called Eval or similiar function available in F# ? i have already looked on community but could not really get a clear direction.
Here is what i want to achieve
type Parameter = { Paramkey:string; ParamFormula:string; ParamDefaultValue:int }
let p1 = { Paramkey = “p1”; ParamFormula = “10”; ParamDefaultValue = 10; }
let p2 = { Paramkey = “p2”; ParamFormula = “p1*2”; ParamDefaultValue = 20; }
let p3 = { Paramkey = “p3”; ParamFormula = “10+(p1*3*p2)”; ParamDefaultValue = 30; }
let ParameterList = [p1;p2;p3]
let Formula1 = p1.ParamFormula + p2.ParamFormula +p3.ParamFormula
let Formula2 = Formula1*10
call Formula2
the parameter formulas will be coming straight from some datastore .