F# error: This value is not a function and cannot be applied

Question

 let GetVal (i,isMin,al, be)= 
        let b = new Board(board) 
        if b.SetBoardBool(i) then this.MinMaxAlphaBeta(b, isMin, al, be)
        else -2

    let valList = seq{ 
            for i =0 to 8 do 
                yield (GetVal i (not isMin) alphaF betaF ,  not isMin)
                }

I am getting an F# error saying: This value is not a function and cannot be applied.

valList is sequence of tuples of int and bool and GetVal takes int bool int int and returns int. where alphaF betaF are mutable variables.

I think you'd be far better served to buy a good F# book and read it and work through the exercises in the book. Trying to learn F# by hacking on code without really understanding what the code is doing is probably a waste of your time and ours. — Onorio Catenacci, Oct 06 '13 at 18:30
By the way, using magic numbers http://en.wikipedia.org/wiki/Magic_number_(programming) in code is generally a bad practice and one you should avoid where possible. What does -2 mean in the code above? — Onorio Catenacci, Oct 06 '13 at 18:34

score 4 · Accepted Answer · answered Oct 06 '13 at 19:07

Or you could change the signature of GetVal to not pass a tuple--like this:

let GetVal i isMin al be =

i, isMin, al, and be are called curried parameters. You can find more detail here under the topic "Partial Application of Arguments." I would post a direct link but there doesn't seem to be one.

score 2 · Answer 2 · answered Oct 05 '13 at 08:07

2

Your GetVal function takes tupled arguments (a,b,c,d) whilst you call it with curried arguments a b c d

Something like this should work

yield (GetVal (i, (not isMin), alphaF, betaF) ,  not isMin)

answered Oct 05 '13 at 08:07

John Palmer

25,356
3
48
67

i get this error now. The mutable variable 'betaF' is used in an invalid way. Mutable variables cannot be captured by closures. Consider eliminating this use of mutation or using a heap-allocated mutable reference cell via 'ref' and '!' – Taufiq Abdur Rahman Oct 05 '13 at 14:23
I can't tell from the code you've posted but I'm guessing you created betaF like this: val mutable betaF. The yield in this case is a closure. Look at the answers to this question http://stackoverflow.com/questions/3221200/f-let-mutable-vs-ref And for goodness sake, buy a good F# reference and read it. – Onorio Catenacci Oct 06 '13 at 18:33

F# error: This value is not a function and cannot be applied

2 Answers2