gistfile1.fs

let (|BinaryExpression|_|) (expr:ExpressionSyntax) = 
    match expr with 
    | :? BinaryExpressionSyntax as expr -> Some(expr)
    | _ -> None

let (|LiteralExpression|_|) (expr:ExpressionSyntax) = 
    match expr with 
    | :? LiteralExpressionSyntax as expr -> Some(expr)
    | _ -> None

let (|InvocationExpression|_|) (expr:ExpressionSyntax) = 
    match expr with 
    | :? InvocationExpressionSyntax as expr -> Some(expr)
    | _ -> None