I am trying to install the SpinWheelControl Cocoapod: https://github.com/joshdhenry/SpinWheelControl using swift 5 and Xcode 10.3. Installation is fine but when I go to run, the compiler gives an error:
"The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions"
at this line of code:
let nearestWedge: Int = Int(round(((currentRadians + (radiansPerWedge / 2)) + snappingPositionRadians) / radiansPerWedge))
This type of wheel would be really useful for me if it worked.
Are you able to get this framework running with Swift 5 or perhaps refactor that line of code so it will run?
Thank you!
Try to break the single long expression into small expressions.
For example :
let exp1 = currentRadians + (radiansPerWedge / 2)
let exp2 = (exp1 + snappingPositionRadians) / radiansPerWedge
let nearestWedge = Int(round(exp2))
Related
I write code below:
let array1: [Int] = [0,1]
let array2 = array1 + [2]
It just works.I want to find where + operator define. I search ArrayExtension in my workspace without result.I search Apple doc Collection Sequence Array , there is no result.
Is there a way to navigate to operator definition ,like CMD + CTRL + J for func
Update for Xcode 13: Unfortunately, this does not work in Xcode 13 anymore. There is currently no way to “jump” to the definition of an operator.
Previous answer for Xcode 11: You can select the operator in the Xcode source editor, and choose "Navigate -> Jump to definition" from the menu, or press CMD+CTRL+J.
(This was broken in Xcode 10, but works again in Xcode 11, which is currently in beta.)
Playing with F# and it seems that i cannot find out what is wrong.
FS0003 This value is not a function and cannot be applied. Did you
forget to terminate a declaration?
evaporator 25.0 10.0 10.0
let evaporator (volumeMl:double) (evapPerDaydouble:double) (threshold:double):int =
let mutable counter = 0
let mutable currentVolume = volumeMl
while (currentVolume > (volumeMl * (threshold / 100.))) do
currentVolume <- currentVolume - ((currentVolume * threshold / 100.))
counter <- (counter + 1)
counter
let result = evaporator 25.0 10.0 10.0
printfn "%f" result
Update
modified code with ;;
let result = evaporator 25.0 10.0 10.0;;
And it is working like expected. Strange.
Update 2
The only problem with your initial code is that you've used printfn "%f" instead of printfn "%i".
If your issue is fixed by adding ;; it makes me think you are running this in FSI and seeing the compiler error in FSI. This is fine but perhaps you are typing or pasting code directly in to the FSI prompt?
My advice to everyone starting with F#, and even experienced F# users, is to never type or paste code into FSI. Write code in your editor, select it, and send it to FSI. This way you don't need to worry about remembering semi-colons, and you get compiler errors and suggestions as you type. I have worked in F# day-to-day for years and never had the need to type directly into FSI.
Also, don't forget to re-run all your function and type definitions in FSI if you change them. It's best to reset FSI and start with clean state if you're seeing confusing errors.
This can happen if there is leading whitespace. The following example produces this error.
let x = 1
let y = 2
Removing the leading whitespace resolves the issue.
let x = 1
let y = 2
Setting your editor to show whitespace will help detect this.
The reason adding ;; also helps is because it terminates the blocked code created by the leading whitespace.
I'm using luacheck (within the Atom editor), but open to other static analysis tools.
Is there a way to check that I'm using an uninitialized table field? I read the docs (http://luacheck.readthedocs.io/en/stable/index.html) but maybe I missed how to do this?
In all three cases in the code below I'm trying to detect that I'm (erroneously) using field 'y1'. None of them do. (At run-time it is detected, but I'm trying to catch it before run-time).
local a = {}
a.x = 10
a.y = 20
print(a.x + a.y1) -- no warning about uninitialized field y1 !?
-- luacheck: globals b
b = {}
b.x = 10
b.y = 20
print(b.x + b.y1) -- no warning about uninitialized field y1 !?
-- No inline option for luacheck re: 'c', so plenty of complaints
-- about "non-standard global variable 'c'."
c = {} -- warning about setting
c.x = 10 -- warning about mutating
c.y = 20 -- " " "
print(c.x + c.y1) -- more warnings (but NOT about field y1)
The point is this: as projects grow (files grow, and the number & size of modules grow), it would be nice to prevent simple errors like this from creeping in.
Thanks.
lua-inspect should be able to detect and report these instances. I have it integrated into ZeroBrane Studio IDE and when running with the deep analysis it reports the following on this fragment:
unknown-field.lua:4: first use of unknown field 'y1' in 'a'
unknown-field.lua:7: first assignment to global variable 'b'
unknown-field.lua:10: first use of unknown field 'y1' in 'b'
unknown-field.lua:14: first assignment to global variable 'c'
unknown-field.lua:17: first use of unknown field 'y1' in 'c'
(Note that the integration code only reports first instances of these errors to minimize the number of instances reported; I also fixed an issue that only reported first unknown instance of a field, so you may want to use the latest code from the repository.)
People who look into questions related to "Lua static analysis" may also be interested in the various dialects of typed Lua, for example:
Typed Lua
Titan
Pallene
Ravi
But you may not have heard of "Teal". (early in its life it was called "tl"); .
I'm taking the liberty to answer my original question using Teal, since I find it intriguing.
-- 'record' (like a 'struct')
local Point = record
x : number
y : number
end
local a : Point = {}
a.x = 10
a.y = 20
print(a.x + a.y1) -- will trigger an error
-- (in VS Code using teal extension & at command line)
From command line:
> tl check myfile.tl
========================================
1 error:
myfile.tl:44:13: invalid key 'y1' in record 'a'
By the way...
> tl gen myfile.tl'
creates a pure Lua file: 'myfile.lua' that has no type information in it. Note: running this Lua file will trigger the 'nil' error... lua: myfile.lua:42: attempt to index a nil value (local 'a').
So, Teal gives you a chance to catch 'type' errors, but it doesn't require you to fix them before generating Lua files.
UPDATE:
I now realize that the question was stupid, I should have just filed the issue. In hindsight, I don't see why I even asked this question.
The issue is here: https://github.com/fsharp/FSharp.Compiler.Service/issues/544
Original question:
I'm using FSharp Compiler Services for parsing some F# code.
The particular piece of code that I'm facing right now is this:
let f x y = x+y
let g = f 1
let h = (g 2) + 3
This program yields a TAST without the (+) call on the last line. That is, the compiler service returns TAST as if the last line was just let h = g 2.
The question is: is this is a legitimate bug that I ought to report or am I missing something?
Some notes
Here is a repo containing minimal repro (I didn't want to include it in this question, because Compiler Services require quite a bit of dancing around).
Adding more statements after the let h line does not change the outcome.
When compiled to IL (as opposed to parsed with Compiler Services), it seems to work as expected (e.g. see fiddle)
If I make g a value, the program parses correctly.
If I make g a normal function (rather than partially applied one), the program parses correctly.
I have no priori experience with FSharp.Compiler.Services but nevertheless I did a small investigation using Visual Studio's debugger. I analyzed abstract syntax tree of following string:
"""
module X
let f x y = x+y
let g = f 1
let h = (g 2) + 3
"""
I've found out that there's following object inside it:
App (Val (op_Addition,NormalValUse,D:\file.fs (6,32--6,33) IsSynthetic=false),TType_forall ([T1; T2; T3],TType_fun (TType_var T1,TType_fun (...,...))),...,...,...)
As you can see, there's an addition in 6th line between characters 32 and 33.
The most likely explanation why F# Interactive doesn't display it properly is a bug in a library (maybe AST is in an inconsistent state or pretty-printing is broken). I think that you should file a bug in project's issue tracker.
UPDATE:
Aforementioned object can be obtained in a debbuger in a following way:
error.[0]
(option of Microsoft.FSharp.Compiler.SourceCodeServices.FSharpImplementationFileDeclaration.Entity)
.Item2
.[2]
(option of Microsoft.FSharp.Compiler.SourceCodeServices.FSharpImplementationFileDeclaration.MemberOrFunctionOrValue)
.Item3
.f (private member)
.Value
(option of Microsoft.FSharp.Compiler.SourceCodeServices.FSharpExprConvert.ConvExprOnDemand#903)
.expr
I'm trying to pattern match a binary against this
<<_:(A * ?N + A + B)/binary,T:1/binary,_/binary>>
However it seems erlang throws an error saying that variable T is unbound. Just a quick explanation: I want to ignore a certain number of bytes and then read a byte and then ignore the remaining bytes. How can I achieve this?
In bit syntax we can't use runtime expressions as bit size.
We can use only constants, compile time expressions like _:(4*8)/binary and variables: _:Var/binary.
In your case, solution is to bind A * ?N + A + B to variable first.
IgnoredBytes = A * ?N + A + B,
<<_:IgnoredBytes/binary,T:1/binary,_/binary>> = SomeBinary,
T.
It's Better explained in answer from [erlang-questions]