guard-clause Questions
4
Solved
Do they exist? How are they implemented?
The coroutining predicates of SWI-Prolog (freeze, when, dif etc.) have the functionality of guards. How do they fit in the preferred Prolog programming sty...
Dangle asked 7/12, 2012 at 9:8
4
Solved
I want to write a simple game "guess number" - with n attempts. I want to add some conditions and hits. Is it possible to use guards inside do block ?
Here is my code:
game = return()
game n = do...
Tantalic asked 16/1, 2020 at 22:2
4
Solved
In scala, pattern match has guard pattern:
val ch = 23
val sign = ch match {
case _: Int if 10 < ch => 65
case '+' => 1
case '-' => -1
case _ => 0
}
Is the Raku version lik...
Cordelier asked 13/4, 2018 at 9:56
2
Solved
I came across with the following code recently and it bothers me a lot
lowerSafeForeignCall dflags block
| (entry, middle, CmmForeignCall { .. }) <- blockSplit block
= do
-- do block stuffs
-...
Vigilantism asked 31/5, 2019 at 10:36
4
Solved
I'm learning F# and I've started to play around with both sequences and match expressions.
I'm writing a web scraper that's looking through HTML similar to the following and taking the last URL in...
Thermel asked 11/8, 2016 at 22:44
2
Solved
Suppose I want to model a tree structure in Haskell with
data Tree = Null | Node Tree Integer Tree deriving Show
and I'd like to test if every entry is, say, less than 10. I thought I would use...
Humdinger asked 25/9, 2018 at 23:14
4
Solved
In ML-family languages, people tend to prefer pattern matching to if/else construct. In F#, using guards within pattern matching could easily replace if/else in many cases.
For example, a simple ...
Pater asked 2/11, 2011 at 20:4
2
Solved
In a code base I'm reading, I found a function declaration like this (some parts are missing):
filepathNormalise :: BS.ByteString -> BS.ByteString
filepathNormalise xs
| isWindows, Just (a,xs)...
Duthie asked 1/10, 2017 at 6:37
2
Solved
A common surprise for beginning F# programmers is the fact that the following is an incomplete match:
let x, y = 5, 10
match something with
| _ when x < y -> "Less than"
| _ when x = y ->...
Crowbar asked 17/4, 2017 at 16:21
5
Solved
I'm in the situation where a lot of my classes are containers of well-known but unordered objects of different types, e.g. a container may look as follows:
public class Container
{
public A A { g...
Coleville asked 2/10, 2009 at 12:13
3
Solved
I see two styles of writing the same thing:
def find_nest(animal)
return unless animal.bird?
GPS.find_nest(animal.do_crazy_stuff)
end
vs
def find_nest(animal)
if animal.bird?
GPS.find_nest(...
Toot asked 17/6, 2016 at 11:40
1
Solved
I usually perform guard checking like so:
public void doStuff(Foo bar, Expression<Func<int, string>> pred) {
if (bar == null) throw new ArgumentNullException();
if (pred == null) thr...
Vallo asked 30/6, 2016 at 4:53
5
Solved
What approaches do people take (if any) in managing guard clause explosion in your classes? For example:
public void SomeMethod<T>(string var1, IEnumerable<T> items, int count)
{
if (...
Wakefield asked 20/10, 2009 at 23:27
4
Solved
I just wondered whether it's possible to match against the same values for multiple times with the pattern matching facilities of functional programming languages (Haskell/F#/Caml).
Just think of ...
Popp asked 24/7, 2009 at 17:25
3
Solved
I am getting NameError: undefined local variable or method with ruby 2.1.2
As observed in this question, expressions like:
bar if bar = true
raises an undefined local variable error (provided t...
Betjeman asked 14/8, 2014 at 11:24
1
Solved
In haskell, one could write :
containsTen::Num a => Eq a => [a] -> Bool
containsTen (x : y : xs)
| x + y == 10 = True
| otherwise = False
Is it possible to write something equivalent ...
Breakneck asked 27/7, 2014 at 13:4
4
Solved
Is it possible in F# to pattern match directly against a let binding?
For example, this compiles without any warnings:
let value =
match arg with
| 1 -> "value1"
| 2 -> "value2"
| _ -...
Teresetereshkova asked 15/3, 2014 at 14:4
1
Solved
I have this simple F# function:
let compareNum x =
let y = 10
match x with
| _ when x = y -> 0
| _ when x > y -> 1
| _ when x < y -> -1
However, F# compiler gives me "Incompl...
Voluntarism asked 9/9, 2013 at 4:47
3
i tried to write 3-4 where statement in a one function but i get error and couldnt do it , i tried to do something like that :
foo x=
| x == foo1 = 5
| x == foo2 =3
| x == foo3 =1
| otherwise =2
...
Resendez asked 1/4, 2013 at 9:5
2
Solved
The active pattern in this question fails to compile after upgrading to VS 2012 RTM. It provides a way to do a type test and match a literal within a single pattern. For example:
let (|Value|_|) v...
Roseboro asked 16/8, 2012 at 14:28
2
Solved
I define a point
type TimeSeriesPoint<'T> =
{ Time : DateTimeOffset
Value : 'T }
and a series
type TimeSeries<'T> = TimeSeriesPoint<'T> list
where I assume the points in ...
Ovoviviparous asked 5/7, 2012 at 23:59
3
Solved
I do agree with Mark Seeman's notion that Automatic Properties are somewhat evil as they break encapsulation. However I do like the concise syntax, readability and convenience they bring.
I quote:...
Personal asked 21/7, 2011 at 8:23
2
Solved
I'm trying to automate file comment headers. I'm stuck trying to figure out how to insert the result of the uuidgen command into my header using vim's autocmd.
Inside the header, the placeholder t...
Fogbow asked 5/5, 2010 at 15:10
18
In my C# code, I have an if statement that started innocently enough:
if((something == -1) && (somethingelse == -1) && (etc == -1)) {
// ...
}
It's growing. I think there must b...
Gnome asked 8/6, 2009 at 17:4
1
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