Error when try to get value in Call Expr -> (Expr option * MethodInfo * Expr list)

Question

Error when try to get value in Call Expr -> (Expr option * MethodInfo * Expr list)

    | Call (A,B,C) -> try_get_return_sig(C.Tail()) // Error at C.Tail
    | Value(A) -> A // Error when get value
let rec try_get_return_sig(ex) = 
    match ex with
    | Lambda (_,ex) -> try_get_return_sig ex
    | Let (a,b,cont) -> Assign(NodeValue(a.ToString()),NodeValue(b.ToString()),try_get_return_sig cont)
    | IfThenElse (a,t,e) -> HoareLogic(try_get_return_sig t,try_get_return_sig a,try_get_return_sig e)
    | Sequential (f,s) -> SeqStatementIntro(try_get_return_sig f, try_get_return_sig s)
    | Call (A,B,C) -> try_get_return_sig(C.Tail()) // Error at C.Tail
    | Value(A) -> A // Error when get value
    | Var var as ex -> NodeValue(var.ToString())
    | b ->  if b.ToString().Contains("op_GreaterThan") then
                Console.WriteLine(b.CustomAttributes.ToString())
                let t = b.GetType()
                if FSharpType.IsUnion(t) then    
                    let union, fields =  FSharpValue.GetUnionFields(b, t)
                    for i = 1 to fields.GetLength(0) do
                        Console.WriteLine(fields.[i].ToString())
            if b.ToString().Contains("op_Equality") then
                Console.WriteLine(b.CustomAttributes.ToString())
                let t = b.GetType()
                if FSharpType.IsUnion(t) then    
                    let union, fields =  FSharpValue.GetUnionFields(b, t)
                    for i = 1 to fields.GetLength(0) do
                        Console.WriteLine(fields.[i].ToString())
                NodeValue(b.ToString())
            else
                NodeValue(b.ToString())
Call Expr -> (Expr option * MethodInfo * Expr list)

Answer 1

Tail is not a function, so there must not be any braces after it.

Also, you should post compiler output message so that people can easily diagnose the problem.

Answer 2

'Expr list' is not compatible with 'Expr'

at | Call (A,B,C) -> try_get_return_sig(C.Tail)

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The will of planet

Answer 3

I don't know what do you expect to get, but compiler is perfectly correct. C.Tail is a list of arguments, and try_get_return_sig obviously expects single expression, not a list of expressions.

Answer 4

my goal is http://social.msdn.microsoft.com/Forums/en-US/fsharpgeneral/thread/a430efe0-e5d7-46d3-8d99-d7933bc6077f

just want to programming into logic

final result will be something like

type expr =  
| Conj of expr * expr
| Disj of expr * expr
| GreaterThan expr * expr
| NodeValue of string
Disj(Conj(GreaterThan(x,1),NodeValue(2)),Conj(Neg(GreaterThan(x,1)),NodeValue(3))

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The will of planet

Answer 5

| Call (A,B,C) -> match B.ReturnParameter.Member.Name with
                      | "op_Equality" -> Equal(NodeValue("x"), try_get_return_sig(List.head(List.rev(C))))
                      | _ -> try_get_return_sig(List.head(List.rev(C)))
    | Value(A) -> NodeValue(fst(A).ToString())

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