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In GHC (without language extensions) I have to do this:
x = 2 Prelude.+ 1
-- valid: x = (Prelude.+) 2 1
-- invalid: x = Prelude.+ 2 1
-- also invalid: x = 2 `Prelude.+` 1
How to change this behavior?
Quoting the Haskell Report, section 2.4:
The qualifier does not change the syntactic treatment of a name; for example, Prelude.+ is an infix operator with the same fixity as the definition of + in the Prelude
So, assuming the Prelude qualifier is just an example and you want to use the syntax shown in the comments, I don't think there is a way.
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How to take operator as input and how to perform operations using tat operator
I have tried using functions
If we provide the input 2,5,+. the program should give output as 7.
I'm not going to give you all of the code, but here's a good starting point.
In Python, check out the operator module:
>>> import operator
>>> sum = operator.add(2, 5)
>>> sum
7
>>> diff = operator.sub(2, 5)
>>> diff
-3
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I am trying to code something in Haskell and can't find a breakthrough. What I'm trying to do, is from GHCi input one pair of numbers, do some equations with them and print out results. Let say the input is (a,b). Equations could be as simple as c = b **2 + a **3 - sin b and d = a - b
The output should be (c,d). Is it possible to do it and how.
Here is a sample ghci session:
> a = 3
> b = 4
> (b**2 + a**3 - sin b, a - b)
(43.75680249530793,-1)
If this does not meet your needs, you will need to be more specific about your needs (preferably in a fresh question that refers to this one and explains why the new question is different from this one).
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I am learning Haskell, studying for a midterm. there is a test quiz I'm looking at at the moment with questions on type inference. some of the questions contain forward slashes and I have no idea what they represent. the goal is to determine the type of the function by looking at its variables. here are some examples of the questions im supposed to find the type of:
f1 x = (/x)
f3 x = (x/)
f5 = (1/)
f6 = (/2)
I have googled with no luck, what does the forward slash mean?
These are sections: the expression (/x) is equivalent to \y -> y / x and (x/) is equivalent to \y -> x / y.
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My Question is that: Is it possible to show (2^63::Int) in 128 bit in Haskell?
Because of Int abs (2^63::Int) will not work because of the Int, but What If I have a 128 bit computer or compiler is it possible then to show the result?
Of course if it is possible, then please show me the way :)
According to the Report, this question is implementation specific:
The finite-precision integer type Int covers at least the range [-2^29, 2^29-1]. As Int is an instance of the Bounded class, maxBound and minBound can be used to determine the exact Int range defined by an implementation.
I know of no implementations for which maxBound :: Int is larger than 2^63-1.
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I just started with haskell and im wondering if there is a easy way to match the letters between 2 string and output them.
like:
iced and liked will return i,e,d
Thank you!
Use Data.Set.intersection:
import qualified Data.Set as S
sharedLetters str1 str2 = S.toList $ S.intersection (S.fromList str1) (S.fromList str2)
EDIT: As #jozefg pointed out, there is a function in Data.List which does the same for lists:
> import Data.List (intersect)
> intersect "liked" "iced"
"ied"