When a value is created in the F# Interactive console the inferred type and contents of the value are displayed.
How can I, at a later date, redisplay the inferred type without showing all the contents?
For example, I have an array, mydata of 1000 items. Typing mydata into the F# Interactive console will display the type, but also the contents of the array.
How about using printfn with the type like so:
F# Interactive for F# 3.1 (Open Source Edition)
Freely distributed under the Apache 2.0 Open Source License
For help type #help;;
>
val mya : int [] = [|3; 2; 5; 6; 7; 8|]
> printfn "%A" (mya.GetType());;
System.Int32[]
val it : unit = ()
You can shorten the typing required by using a little utility function:
let pm v = printfn "%A" (v.GetType())
The you can use as follows:
> pm mya;;
System.Int32[]
val it : unit = ()
"pm" stands for "print me". Call it whatever you want :)
Another approach if you don't like the type names from GetType() is just to cause an error with the value you want to evaluate. That will give you a more friendly F# type name (if you don't mind ignoring the error of course). For instance on a list you could do:
>
val myl : string list = ["one"; "two"]
> printfn myl;;
Script.fsx(195,9): error FS0001: The type 'string list' is not compatible with the type 'Printf.TextWriterFormat<'a>'
Note the type string list between the ''
Lastly you can use: (MSDN)
fsi.ShowDeclarationValues <- false
But this only silences the initial evaluation.