folks, how do I check for the supply of a mint account on-chain?
I have no idea on how to do this.
I've tried using:
let mint = Mint::unpack_unchecked(accounts.mint.data).unwrap();
Then I get this error:
expected reference `&[u8]`
found struct `Rc<RefCell<&mut [u8]>>`
Also, in my function, if I try to get accounts.mint.data to &[u8]format by doing this:
let data = accounts.mint.data.borrow().as_ref();
I get this non-sense error:
consider using a `let` binding to create a longer lived valuerustcE0716
mod.rs(98, 64): temporary value is freed at the end of this statement
mod.rs(99, 51): borrow later used here
Nevermind:
let mint = Mint::unpack_unchecked(&accounts.mint.data.borrow()).unwrap();
to get the supply, just access mint.supply
Related
I am facing an issue when I try to use the function Deedle.Frame.ReadCsv
I am trying to use the overload here: https://collective2.com/c2explorer_help/html/806c0295-1a9f-1bf4-50eb-a221419abe06.htm
let schemaSource = "dateRep (DateTime),,,,,,,,,"
let dataSource = Deedle.Frame.ReadCsv(path = "data.csv", schema = schemaSource)
When I do so, I get the following error:
error FS0503: A member or object constructor 'ReadCsv' taking 0 arguments is not accessible from this code location. All accessible versions of method 'ReadCsv' take 9 arguments.
What I do not get is that all but path are optional. If I use just:
Deedle.Frame.ReadCsv("data.csv")
It then works...
Any idea? I tried to find some resources on using overloaded functions from other .Net languages with optional parameters but I have not been successful.
I am not sure why the Intellisense/Signature shown in Visual Studio was wrong but using location = works...
I am an absolute newbie to coding, but I need to modify a F# script. It always gives me the error "Method or object constructor 'x' is not static". I read that this might be due to the fact that I try to call a non-static method within a module, which is by default static. For example 'x' = Get.Axis():
module Primitives =
let axis1 = Zaber.Motion.Ascii.Device.GetAxis(1)
The manual only provides code in C#: var axis1 = device.GetAxis(1);
If I use static member instead of let, I'll get a 'unexpected keyword static in definition' error, although I checked the indentation as suggested in another question.
Assuming you're using the Zaber Motion Library, I think what you need to do is get an instance of a device first, instead of trying to access the class in a static context.
Their documentation includes an example of how to get a list of devices by opening a serial port:
open Zaber.Motion.Ascii
use connection = Connection.OpenSerialPort("COM3")
let deviceList = connection.DetectDevices()
match deviceList |> Seq.tryHead with // See if we got at least one device
| Some device ->
let axis = device.GetAxis(1)
// TODO: Do whatever you want with the axis here
| None ->
failwith "No Devices Found on COM3"
I'm trying to make a Pokemon Red/Blue Chaos Edition, but like everyone else asking question on this site, I've encountered a bug that I cannot fix. I am using version 2.2.2 (x64) of BizHawk. The error is as follows:
NLua.Exceptions.LuaScriptException: [string "main"]:12: invalid arguments to method call
https://pastebin.com/pWmByXum
I did some research, and came to the conclusion that it's trying to run line 12 as a function even though I have none.
rng is being defined as a local variable inside the if block. It is therefore not available outside of that block when it is used as an argument to the call on line 12. At that point it would be nil. Move the declaration of rng to above the if block:
local rng = nil
Then in both places in fhe if block when you assign a value, just write:
rng = ...
instead of
local rng = ...
rng will then get assigned a value, but be available outside of the if block
Say:
let x = // some operation
type t = SomeTypeProvider<x>
Is this valid?
No.
Since the types must be generated at compile-time, the parameter to the type provider needs to be a constant.
In other words, the code you marked // some operation can evaluate to a literal, but cannot be a value returned by a runnable function:
let arg = "foo"
type t = SomeTypeProvider<arg> // okay
let [<Literal>] arg = """{"name":"foo","value":42}"""
type t = SomeTypeProvider<arg> // okay
let arg = x.ToString()
type t = SomeTypeProvider<arg> // Boom! arg is not a Literal
It depends on your application, but one of the most common cases is the following:
You have a database-related Type Provider, and the connection string needs to be retrieved in runtime, from some sort of config file or something. So a developer mistakenly thinks they need a runnable code to retrieve the connection string first and then pass it to the Type Provider.
The correct approach is the following:
Keep two databases: one locally stored in a constant location (just for schema), and another one for the runtime purposes.
Pass the first one (a constant!) to your Type Provider. Don't worry about the hardcoded paths; it is only used for schema retrieval.
// Use a fixed sample file for schema generation only
type MyCSVData = CsvProvider<"dummy.csv">
// Load the actual data at runtime
let data = MyCSVData.Load(RetrieveFileNameFromConfig())
i have got several times , trying to implement different functions, the message you see as title. I would like to know if anyone can tell me the general meaning (and reason) of this error message. As i mentioned before, i have got the problem several times and manage to fix it, but still didnt get the exact reason, so i will not post any specific code.
Thank you in advance
The most common case when you may get this error is when you write let binding that is not followed by an expression that calculates the result. In F#, everything is an expression that returns some result, so if you write let a = 10 it is generally not a valid expression. To make it valid, you need to return something:
let foo () =
let a = 10
() // return unit value (which doesn't represent any information)
The only exception where you can write just let a = 10 is a global scope of an F# source file - for example, inside a module declaration or in an F# script file. (This is why the declaration of foo above is valid).
It is difficult to give any advice without seeing your code, but you probably have a let declaration that is not followed by an F# expression.
Out of curiosity, the following example shows that let can really be used inside an expression (where it must return some meaningful result):
let a = 40 + (let a = 1
a + a)