How to read byte array from file in Haskell?

Question

When I want read bytes from a file in Java, I can do like this:

InputStream is = new FileInputStream(...);
while((int b = is.read()) != -1){
    //...analysis the bytes.
}

And how do it in Haskell? I don't see any function witch can read bytes module System.IO and Data.ByteString.

stackage.org/haddock/lts-12.8/bytestring-0.10.8.2/…

Sibi
– Sibi

2019-01-03 05:36:13 +00:00
Commented Jan 3, 2019 at 5:36 — Sibi
– Sibi, Commented Jan 3, 2019 at 5:36

talex · Accepted Answer · 2019-01-03 06:25:10Z

2

Use readFile

import Data.ByteString(readFile)

main = do 
    content <-  Data.ByteString.readFile "path/to/file"
    print content

It read the file and print it content on screen.

edited Jan 3, 2019 at 6:25

answered Jan 3, 2019 at 5:44

talex

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5 Comments

talex Over a year ago

It read ByteString which is in fact array of Word8 which is smart way to name byte.

Jacky Wong Over a year ago

So you mean I don't need to import ByteString to read Word8 which like Byte in Java ?

talex Over a year ago

Easiest way to check that is to try, but yes, you don't need to import it.

Potato44 Over a year ago

@talex the readFile in prelude reads into a String. It appears the question asker wants to read into bytes rather then characters. I think ByteString is the correct thing for that.

talex Over a year ago

@Potato44 then proper (Data.ByteString) function should be imported.

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