[Haskell-cafe] clz / bsr functions on Integer

[David James]

Hi – there is a countLeadingZeros function. It applies to instances of FiniteBits, such as Int (a fixed bit-size integer):

GHCi, version 8.10.7: https://www.haskell.org/ghc/  :? for help
Loaded package environment from C:\Users\David\AppData\Roaming\ghc\x86_64-mingw32-8.10.7\environments\default
> :m +Data.Bits
> countLeadingZeros (23 :: Int)
59
>

The Integer type represents unbounded integers, so countLeadingZeros doesn’t really make sense.

(ps. you can seach for functions like countLeadingZeros on Hoogle<https://hoogle.haskell.org/>).

Hope that helps, David.


From: james faure<mailto:james.faure at epitech.eu>
Sent: 13 November 2021 00:16
To: haskell-cafe at haskell.org<mailto:haskell-cafe at haskell.org>
Subject: [Haskell-cafe] clz / bsr functions on Integer

Why is there no `countLeadingZeros` function for Integer? This seems particularly strange because gmp provides mp_bitcnt_t mpz_scan0 (const mpz_t op, mp_bitcnt_t starting_bit)

More importantly, what is the recommended way to access it?

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