The computation
appendFile file str function appends
the string
str, to the file
file.
Note that
writeFile and
appendFile write a literal
string to a file. To write a value of any printable type, as with
print, use the
show function to convert the value to a
string first.
This operation may fail with the same errors as
hPutStr and
withFile.
Examples
The following example could be more efficently written by acquiring a
handle instead with
openFile and using the computations capable
of writing to handles such as
hPutStr.
>>> let fn = "hello_world"
>>> in writeFile fn "hello" >> appendFile fn " world!" >> (readFile fn >>= putStrLn)
"hello world!"
>>> let fn = "foo"; output = readFile' fn >>= putStrLn
>>> in output >> appendFile fn (show [1,2,3]) >> output
this is what's in the file
this is what's in the file[1,2,3]