[Haskell-cafe] nested function application question
rmm-haskell at z.odi.ac
Mon Jan 5 13:29:10 EST 2009
In this case you have to use parens -- two dollar signs, like this
B.intercalate $ B.intercalate ByteString [ByteString] $ [ByteString]
would also not type check -- it is exactly equivalent to your first
B.intercalate (B.intercalate ByteString [ByteString] ([ByteString]))
just with one level of extra parentheses.
If for some reason you absolutely need to avoid parentheses (mostly as
a thought exercise, I guess), you'd have to have a flipped version of
flippedIntercalate :: [ByteString] -> ByteString -> ByteString
flippedIntercalate = flip B.intercalate
flippedIntercalate [ByteString] $ B.intercalate ByteString [ByteString]
of course, this is pretty contrived.
On Jan 5, 2009, at 1:23 PM, Galchin, Vasili wrote:
> yep ... that is exactly what I meant!! so can I use more $'s or must
> I use parens (as you did) to disambiguate?
> On Mon, Jan 5, 2009 at 12:18 PM, Ross Mellgren <rmm-
> haskell at z.odi.ac> wrote:
> Did you mean:
> B.intercalate (B.intercalate ByteString [ByteString]) [ByteString]
> ($) applies all the way to the right, so you were giving the inner
> intercalate two lists of ByteString.
> On Jan 5, 2009, at 1:17 PM, Galchin, Vasili wrote:
>> Hi Max,
>> That is what should happen .... The inner B.intercalate will
>> produce the ByteString to be used by the B.intercalate. ??
>> On Mon, Jan 5, 2009 at 12:13 PM, Max Rabkin <max.rabkin at gmail.com>
>> 2009/1/5 Galchin, Vasili <vigalchin at gmail.com>:
>> > Hello,
>> > I have the following:
>> > B.intercalate $ B.intercalate
>> > ByteString
>> > [ByteString]
>> > [ByteString]
>> > I get a type error with this. If I comment out the 2nd
>> > and the third parameter I get no type errors.
>> B.intercalate needs a ByteString and a list of ByteStrings. Two
>> B.intercalates need two ByteStrings and two lists of ByteStrings.
>> Haskell-Cafe mailing list
>> Haskell-Cafe at haskell.org
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