Is there a way to assign the same value to multiple variables in Haskell? e.g something like this:
h,f = 5
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Just out of curiosity: Is there some other language you have in mind that can do this? – Chris Martin Mar 12 '18 at 06:43
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@ChrisMartin Maybe [this one](https://stackoverflow.com/questions/16348815/python-assigning-multiple-variables-to-same-value-list-behavior). – wisn Mar 12 '18 at 06:50
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@ChrisMartin in Python you can do `h = f = 5`. – Elmex80s Mar 12 '18 at 09:10
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@ChrisMartin In R you can even do `f <- 5 -> h` – Stéphane Laurent Mar 12 '18 at 19:46
1 Answers
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Prelude> let [x, y] = replicate 2 5
Prelude> x
5
Prelude> y
5
Prelude>
You need replicate to "duplicate" a value. In this case, I duplicating 5 twice. [x, y] mean get x and y from a List. That list is [5, 5]. So, you got x = 5 and y = 5.
Well, I never did such behavior in the real world Haskell but you get what you want.
EDIT: We could use repeat function and the feature of lazy evaluation in the Haskell. Thanks to luqui.
Prelude> let x:y:_ = repeat 5
Prelude> x
5
Prelude> y
5
Prelude>
wisn
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2If you want to avoid the possible pattern match error if you mismatch the length of the list with the number to replicate, use `repeat` instead: `let x:y:_ = repeat 5`. And I, too, have never seen this idiom in the wild, and suspect it to be rather futile for reasons @absolutezero mentions. – luqui Mar 12 '18 at 08:02
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@luqui I forgot that I could use `repeat` and the feature of lazy evaluation. Thanks! – wisn Mar 12 '18 at 08:21