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FHASH QUESTIONS

How Reflection MakeUnion three level type?
How Reflection MakeUnion three level type?
hop of those help? The reason you're getting the exception is that when you call getAll in the recursive case for B1, the field type is C, and C has two cases, C1 | C2, so you get back an array of two elements. Then, that array is passed to the MakeU
TAG : fhash
Date : January 02 2021, 06:48 AM , By : pdkent
Is it possible to require statically resolved type parameter to be a generic type?
Is it possible to require statically resolved type parameter to be a generic type?
around this issue You can try to do define the add function and then assign it to infix operator:
TAG : fhash
Date : January 02 2021, 06:48 AM , By : user152423
Matching Patterns for list of tuples
Matching Patterns for list of tuples
will help you Your match expression has a final catch-all clause (the _ clause) that just calls getVar again with the same parameters. If the when (fst head) = exp condition fails, then code falls through to the catch-all clause, so getVar gets calle
TAG : fhash
Date : January 02 2021, 06:48 AM , By : Gianluca Riccardi
F# Array.tryFindIndex start search from an index
F# Array.tryFindIndex start search from an index
around this issue The base libraries try to provide functions for your convenience but they cannot possibly anticipate all use cases. Nothing wrong with writing your own if need be:
TAG : fhash
Date : January 02 2021, 06:48 AM , By : DicksGarage
Why some common standards were redefined in F#?
Why some common standards were redefined in F#?
I wish this helpful for you I have started F a few days ago and I do not understand why some things which have been common for very long have been redefined?
TAG : fhash
Date : January 02 2021, 06:48 AM , By : k19k
Pattern matching with type annotations
Pattern matching with type annotations
I hope this helps you . Actually, even when you use type annotation in function parameters, you are using type annotation in patterns too. F pattern matching works even on function parameters (let binding in general).So, as usual, type annotation is
TAG : fhash
Date : January 02 2021, 06:48 AM , By : Nulq
Passing a F# struct to C#
Passing a F# struct to C#
With these it helps To create List out of any other enumerable (including F list) use the .ToList extension method from System.Linq.Enumerable:
TAG : fhash
Date : January 02 2021, 06:48 AM , By : RyanMcG
how to use list.filter when the function called has several parameters, in F#?
how to use list.filter when the function called has several parameters, in F#?
will be helpful for those in need You can use List.choose:
TAG : fhash
Date : January 02 2021, 06:48 AM , By : hlpimfalling
How can I declare an object into another class on F#?
How can I declare an object into another class on F#?
To fix the issue you can do You are probably getting an error because module.Owe is not a correct way of referencing a type from another module. You do not need the module keyword here - you just need to give the module name and the class name as in
TAG : fhash
Date : January 02 2021, 06:48 AM , By : Pradeep Gowda
This expression was expected to have type 'obj' but here has type 'string'
This expression was expected to have type 'obj' but here has type 'string'
Hope that helps According to the Fabulous Guide (https://fsprojects.github.io/Fabulous/views-perf.html) you need to box the list elements:
TAG : fhash
Date : January 02 2021, 06:48 AM , By : Barry
Create sequence from multidimensional array in F#
Create sequence from multidimensional array in F#
With these it helps To answer the second part of your question, you can make the function generic by replacing MyDiscriminatedUnionType type with a generic type parameter such as 'a:
TAG : fhash
Date : January 02 2021, 06:31 AM , By : koder
How to test F# option types with xUnit
How to test F# option types with xUnit
help you fix your problem A general rule of thumb with unit tests is that the Act section should be a single statement.Everything that we want to check about the result is some form of assertion
TAG : fhash
Date : December 31 2020, 04:56 AM , By : Ricardo
With FParsec how would I parse: line ending in newline <|> a line ending with eof
With FParsec how would I parse: line ending in newline <|> a line ending with eof
may help you . FParsec actually has a built-in parser that does exactly what you're looking for: skipRestOfLine. It terminates on either newlines or eof, just like what you're looking for.If you want to try to implement it yourself as a learning exer
TAG : fhash
Date : December 30 2020, 04:10 PM , By : Pepe Araya
In Argu, getting missing argument error for what appears to be an optional parameter
In Argu, getting missing argument error for what appears to be an optional parameter
To fix this issue Instead of making the Count case an int option, leave it an int and call GetResult(...) passing in a default value:
TAG : fhash
Date : December 28 2020, 02:06 PM , By : Stephen
Testing private types with factory constructors
Testing private types with factory constructors
To fix the issue you can do I wouldn't probably go so far to write a test for a smart constructor like the one you have, but if I were writing one, I'd probably just avoid the problem altogether and have a test that checks for a success given a posit
TAG : fhash
Date : December 25 2020, 08:01 PM , By : perl
Async.Parallel doesn't run list |> Async.Parallel |> Async.Ignore |> Async.Start?
Async.Parallel doesn't run list |> Async.Parallel |> Async.Ignore |> Async.Start?
will help you It seems that you have a race condition: ag.Add None happens before the enqueue copies even have a chance to run, because you're starting them on a background thread with Async.Start. In order to maintain the correct order of operations
TAG : fhash
Date : December 25 2020, 06:01 PM , By : George Handlin
F# How to write a function that takes int list or string list
F# How to write a function that takes int list or string list
I hope this helps you . You are running into value restrictions on the automatic generalization of the type inference system as outlined hereSpecifically,
TAG : fhash
Date : December 25 2020, 11:30 AM , By : semicolonth
Result bind with different types?
Result bind with different types?
seems to work fine Can be solved by removing the generic parameter and using a single Error DU. Unfortunately this loses the signature I wanted, but it will have to do.
TAG : fhash
Date : December 25 2020, 09:19 AM , By : James Cary
F# query expression nested lists
F# query expression nested lists
Any of those help I'm trying to query a list of events each containg a list of attendees. I'm using a query expression on an EF db context. I've managed to do it like this: , What you're doing is pretty much exactly what groupJoin does.
TAG : fhash
Date : December 23 2020, 06:30 PM , By : user113409
How to write generic type and duck typing in the same function?
How to write generic type and duck typing in the same function?
Hope that helps To be perfectly honest, I'm not sure why this happens. Perhaps it's because you need to specify all type parameters explicitly, if you specify one? As I said, I don't know. However, adding another type parameter to the test function a
TAG : fhash
Date : December 05 2020, 12:02 PM , By : Patastroph
F# XLinq traversal - curried version of function throws StackOverflowException
F# XLinq traversal - curried version of function throws StackOverflowException
wish helps you Look: every time you call nestedCurried, you call nestedCurried again, right away, unconditionally.To make things a bit clearer, consider that the expression List.collect f is equivalent to let x = f; List.collect x. This means that yo
TAG : fhash
Date : December 01 2020, 05:00 PM , By : user150744
Why doesn't manyCharsTill combinator work if the "till" parser starts with spaces?
Why doesn't manyCharsTill combinator work if the "till" parser starts with spaces?
To fix the issue you can do The issue is that spaces parses successfully and moves the stream to the beginning of w. pstring "" then fails. The end result is that the endp parser has failed, but it has changed the state (we've moved past the spaces).
TAG : fhash
Date : December 01 2020, 04:47 PM , By : user177910
What is the idiomatic F# equivalent to declaring a variable for later use in C#
What is the idiomatic F# equivalent to declaring a variable for later use in C#
seems to work fine You can use functions and values. There is no need to declare unassigned variables.
TAG : fhash
Date : November 29 2020, 03:01 PM , By : Steve M
AsyncResult and handling rollback
AsyncResult and handling rollback
around this issue (warning: this was posted also on https://forums.fsharp.org/t/asyncresult-and-handling-rollback/928) , Just do some error handling outside the workflow, like this:
TAG : fhash
Date : November 29 2020, 12:01 PM , By : Brian Drum
Loading assembly dynamically from a Typeprovider
Loading assembly dynamically from a Typeprovider
will help you Someone linked this answer, which has an explanation of the issue and a solution:Type provider calling another dll in F
TAG : fhash
Date : November 28 2020, 09:01 AM , By : Marc
Time to live memoization in F#
Time to live memoization in F#
around this issue If you are willing to limit what to memoize to functions that take a string input, you can reuse the functionality from System.Runtime.Caching.This should be reasonably robust as part of the core library (you would hope...) but the
TAG : fhash
Date : November 28 2020, 08:01 AM , By : Frank Rotolo
Scoping assignment
Scoping assignment
will help you The let keyword creates a name binding, which means "this name means this value" (or this function). It is immutable: in the code you wrote, the name z in the split function will always refer to the value abs(x / 10), and cannot be chan
TAG : fhash
Date : November 26 2020, 11:01 PM , By : James
Simple explanation of List.Fold and List.Foldback in F#
Simple explanation of List.Fold and List.Foldback in F#
I hope this helps you . The best way to understand it is with an example. Imagine you have list of numbers and you want to find out the total. In imperative programming you could do this:
TAG : fhash
Date : November 25 2020, 07:22 PM , By : Novi Indrayani
F# Type Provider compiled as *.exe file
F# Type Provider compiled as *.exe file
I wish this helpful for you Perhaps there's some good underlying reason for always looking for DLLs instead of EXEs, but I suspect this may be an arbitrary limitation.I can get things to work in FSI if I supply the assembly's full name to the TypePro
TAG : fhash
Date : November 25 2020, 07:22 PM , By : Bjørn Lyngwa
How to construct a list of float<metre>?
How to construct a list of float<metre>?
wish of those help I reported this to the F team a while ago, but you need to specify the step manually when using Measures.
TAG : fhash
Date : November 25 2020, 07:06 PM , By : matthew
Imagesharp mutate in F#
Imagesharp mutate in F#
it helps some times F can automatically convert from an anonymous function (fun ...) to a System.Action, but only if the types match exactly. Here, they don't, because Kodachrome() doesn't return unit. So you need to ignore its return value:
TAG : fhash
Date : November 23 2020, 03:01 PM , By : apple
f# finding the indexes of a string in a char array
f# finding the indexes of a string in a char array
I wish did fix the issue. Hey all i am new to F , Here's a solution using recursive functions:
TAG : fhash
Date : November 23 2020, 12:01 PM , By : George Handlin
Insert type into F# tree
Insert type into F# tree
wish help you to fix your issue This is the solution that I was able to come up with. I wouldn't doubt that a more efficient answer exist.
TAG : fhash
Date : November 22 2020, 11:00 PM , By : BooTeK
F# - Writing a function that accepts both non-generic and generic argument
F# - Writing a function that accepts both non-generic and generic argument
it should still fix some issue Your original definition for await is fine. The problem is with unitTask which is not generic. Make it generic the same way you did with stringTask:
TAG : fhash
Date : November 22 2020, 04:01 AM , By : user157138
Encapsulating mutable states
Encapsulating mutable states
will help you Think of it this way: incr is a value, not a function. Its value is a closure that captures some state (i.e., counter). It's the closure that is subsequently being called potentially multiple times (incr is only executed/assigned once).
TAG : fhash
Date : November 17 2020, 12:01 PM , By : FriendL
F# "this rule will never be matched" expression in a NOT recursive function
F# "this rule will never be matched" expression in a NOT recursive function
I hope this helps you . You can't match against a variable, I mean you can but if you do so what would happen is that the variable will be bound to that value and it seems to me that's not what you are trying to do, otherwise the first case in your c
TAG : fhash
Date : November 17 2020, 11:52 AM , By : boney M
f# signature matching explained
f# signature matching explained
seems to work fine I think that part of the problem comes from mixing methods (OO style) and functions (FP style). FP style functions have multiple parameters separated by spaces. OO style methods have parens and parameters separated by commas. Metho
TAG : fhash
Date : November 17 2020, 01:00 AM , By : Yst
Can this random number generator logic be simplified?
Can this random number generator logic be simplified?
fixed the issue. Will look into that further You could define a helper function to perform a Fisher-Yates shuffle. This shuffle function is pretty generally useful since it will work on any seq
TAG : fhash
Date : November 14 2020, 07:01 AM , By : mikhaelrasputin
Assigning a value post while-loop results in error
Assigning a value post while-loop results in error
I hope this helps you . as far as I can tell it's just because you mixed tabs and spaces in there - and in deed this works if I evaluate it in FSharpInteractive:
TAG : fhash
Date : November 14 2020, 06:58 AM , By : Jim Davis
Discriminated Union initialization
Discriminated Union initialization
hop of those help? I don't think that there's a more succinct way, but I also wouldn't model playing cards like this, because it doesn't help making illegal states unrepresentable. As an example, I can do this:
TAG : fhash
Date : November 13 2020, 09:01 AM , By : Paul McKee
Defining tuple data types in the function signature on F#
Defining tuple data types in the function signature on F#
wish help you to fix your issue First, the following code block is defining five functions, not five integer values:
TAG : fhash
Date : November 12 2020, 04:01 AM , By : todor
Nested loop and functional programming
Nested loop and functional programming
I wish this helpful for you You have to add those checks in the match.See here what your code is missing:
TAG : fhash
Date : November 09 2020, 03:01 PM , By : Fahad
Using XML-Typeprovider from another Module
Using XML-Typeprovider from another Module
this one helps. You can separate the samples out into their own files.I use it in the following way
TAG : fhash
Date : November 06 2020, 04:01 AM , By : Edo
Why is Type Annotation Required Here?
Why is Type Annotation Required Here?
With these it helps Because the type parameter 'T is not referenced in the body of the function, so type inference has no way to know your intention was to name 'T the return type.So you can either add it in the body as the return type (as you alread
TAG : fhash
Date : November 04 2020, 08:15 AM , By : MikeG
How to return a value from a function based on conditions
How to return a value from a function based on conditions
To fix this issue You're just missing a final else (value). The structure of your if statement is if...elif, but you need it to be if...elif...else, otherwise there's at least one code path through your function that doesn't return a value. Add else
TAG : fhash
Date : November 03 2020, 09:01 AM , By : DaveF
F# List of Tuples
F# List of Tuples
wish helps you It sounds very similar to your previous question ...Make a List from a Tuple List on F
TAG : fhash
Date : November 03 2020, 04:01 AM , By : quicky
Pattern match on a list of tuples
Pattern match on a list of tuples
it helps some times If I want to add all the elements of a list of tuples, I get an error with the following , You just forgot a pair of parens
TAG : fhash
Date : November 01 2020, 12:01 AM , By : user179190
How do i convert the result of the input into an int in F#?
How do i convert the result of the input into an int in F#?
hop of those help? Use (int)input int input. Under the covers this parses the input and returns an int or throws a System.FormatException.Another option is to use Int32's TryParse method and return the both the result and success indicator as a tuple
TAG : fhash
Date : November 01 2020, 12:01 AM , By : Luciano Campos
Unable to perform basic arithmetic
Unable to perform basic arithmetic
will be helpful for those in need In F, I receive an error when I write the following code: , You need to add parentheses:
TAG : fhash
Date : October 31 2020, 01:52 PM , By : user185949
Is List.where identical to List.filter?
Is List.where identical to List.filter?
I wish this helpful for you Yes, they're identical; I assume .where's existence is solely for LINQ users who would wonder where it is otherwise.
TAG : fhash
Date : October 29 2020, 04:01 PM , By : Star Gryphon
F# Piping a parameter into higher-order function or declaring own function
F# Piping a parameter into higher-order function or declaring own function
This might help you I have a function which processes an input list into a different type but that in itself is not the interesting thing here. , I think your pipe is wrong, it should be:
TAG : fhash
Date : October 29 2020, 04:01 PM , By : Vodkat
is an "optionalized" pipe operator idiomatic F#
is an "optionalized" pipe operator idiomatic F#
it should still fix some issue I like to use the pipe operator '|>' a lot. However, when mixing functions that return 'simple' values with functions that return 'Option-Typed-values', things become a bit messy e.g.: , I think using Option.map would b
TAG : fhash
Date : October 29 2020, 06:12 AM , By : user157064
Make a List from a Tuple List on F#
Make a List from a Tuple List on F#
To fix the issue you can do You need to filter the list first to get tuples that have an x value of 1, then map the results to get the y value :
TAG : fhash
Date : October 29 2020, 05:01 AM , By : user118656
Ignoring backslash and double quotes in F#
Ignoring backslash and double quotes in F#
I think the issue was by ths following , The @ sign doesn't "ignore" backslashes in the sense that they don't appear in the string, it simply treats them as normal characters, instead of as characters with a special meaning. E.g.,
TAG : fhash
Date : October 29 2020, 05:01 AM , By : Blight
Functional increment
Functional increment
To fix the issue you can do You're introducing a new q binding for the result of the expression evaluated in your first case match rather than comparing against it. What you want is something like this:
TAG : fhash
Date : October 28 2020, 04:01 PM , By : Meg
How to leverage power of TextWriterFormat for printfn style in combination with ConditionalAttribute which requires unit
How to leverage power of TextWriterFormat for printfn style in combination with ConditionalAttribute which requires unit
should help you out I set myself to creating a trace function that behaves like sprintf or printfn, but is disabled (JIT removes it on call site) for Release builds by using the ConditionalAttribute. , An overloading based version.You might want some
TAG : fhash
Date : October 28 2020, 10:01 AM , By : Sandip
F# printf paddings
F# printf paddings
Hope this helps The %5s and %-5s are formatting codes along with width and alignments specified.The hyphen in your first code aligns the value to the left.
TAG : fhash
Date : October 28 2020, 07:41 AM , By : JoeKaras
What is "monadic reflection"?
What is "monadic reflection"?
will be helpful for those in need Monadic reflection is essentially a grammar for describing layered monads or monad layering. In Haskell describing also means constructing monads. This is a higher level system so the code looks like functional but t
TAG : fhash
Date : October 26 2020, 11:52 AM , By : CSCI GOIN KILL ME
Forcing a generic parameter
Forcing a generic parameter
hop of those help? Building on Julien Roncaglia's answer, this method should at least be type-safe because we are using when guards:
TAG : fhash
Date : October 24 2020, 01:32 PM , By : perl
Stack overflow exception when using pipes in tail-recursive function
Stack overflow exception when using pipes in tail-recursive function
like below fixes the issue I think the answer is the same as in the thread Vandroiy links: when you have
TAG : fhash
Date : October 24 2020, 01:32 PM , By : user171555

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