CODEWITHSUNDEEP
haskell
apolune
apolune

Reputation: 457

Why is Data.Word in Haskell called that?

Why is an unsigned integral type in Haskell called "Word"? Does the "ord" stand for "ordinal"?

Here is the documentation on Data.Word: http://hackage.haskell.org/package/base-4.6.0.1/docs/Data-Word.html#t:Word

This is a very hard question to google!

Upvotes: 15

Views: 2333

Answers (1)

bheklilr
bheklilr

Reputation: 54068

From wikipedia:

The term 'word' is used for a small group of bits which are handled simultaneously by processors of a particular architecture. The size of a word is thus CPU-specific. Many different word sizes have been used, including 6-, 8-, 12-, 16-, 18-, 24-, 32-, 36-, 39-, 48-, 60-, and 64-bit. Since it is architectural, the size of a word is usually set by the first CPU in a family, rather than the characteristics of a later compatible CPU. The meanings of terms derived from word, such as longword, doubleword, quadword, and halfword, also vary with the CPU and OS.

In short, a word is a fixed-length group of bits that the CPU can process. We normally work with words that are powers of two, since modern CPUs handle those very well. A word in particular is not really a number, although we treat it as such for most purposes. Instead, just think of it as a fixed number of bits in RAM that you can manipulate. A common use for something like Word8 is to implement ASCII C-style strings, for example. Haskell's implementation treats WordN types as unsigned integers that implement Num, among other type classes.

There is a module called Data.Ord where "Ord" stands for "Ordering". It has extra functions for working with comparisons of datatypes and is where the Ordering datatype and Ord typeclass are defined. It is unrelated to Data.Word.

Upvotes: 23

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