[Haskell-cafe] nested function application question
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 B.intercalate and the third parameter I get no type errors. Regards, Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
2009/1/5 Galchin, Vasili vigalc...@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 B.intercalate 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. --Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
Hi Max, That is what should happen The inner B.intercalate will produce the ByteString to be used by the B.intercalate. ?? Vasili On Mon, Jan 5, 2009 at 12:13 PM, Max Rabkin max.rab...@gmail.com wrote: 2009/1/5 Galchin, Vasili vigalc...@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 B.intercalate 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. --Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
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. -Ross 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. ?? Vasili On Mon, Jan 5, 2009 at 12:13 PM, Max Rabkin max.rab...@gmail.com wrote: 2009/1/5 Galchin, Vasili vigalc...@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 B.intercalate 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. --Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
On Mon, Jan 5, 2009 at 10:17 AM, Galchin, Vasili vigalc...@gmail.com wrote: Hi Max, That is what should happen The inner B.intercalate will produce the ByteString to be used by the B.intercalate. ?? Vasili Of course. My mistake. Ross Mellgren seems to be on the money though. --Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
yep ... that is exactly what I meant!! so can I use more $'s or must I use parens (as you did) to disambiguate? Vasili On Mon, Jan 5, 2009 at 12:18 PM, Ross Mellgren rmm-hask...@z.odi.ac wrote: Did you mean: B.intercalate (B.intercalate ByteString [ByteString]) [ByteString] ($) applies all the way to the right, so you were giving the inner intercalate two lists of ByteString. -Ross 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. ?? Vasili On Mon, Jan 5, 2009 at 12:13 PM, Max Rabkin max.rab...@gmail.com wrote: 2009/1/5 Galchin, Vasili vigalc...@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 B.intercalate 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. --Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
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 example: 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 intercalate: flippedIntercalate :: [ByteString] - ByteString - ByteString flippedIntercalate = flip B.intercalate flippedIntercalate [ByteString] $ B.intercalate ByteString [ByteString] of course, this is pretty contrived. -Ross On Jan 5, 2009, at 1:23 PM, Galchin, Vasili wrote: yep ... that is exactly what I meant!! so can I use more $'s or must I use parens (as you did) to disambiguate? Vasili On Mon, Jan 5, 2009 at 12:18 PM, Ross Mellgren rmm- hask...@z.odi.ac wrote: Did you mean: B.intercalate (B.intercalate ByteString [ByteString]) [ByteString] ($) applies all the way to the right, so you were giving the inner intercalate two lists of ByteString. -Ross 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. ?? Vasili On Mon, Jan 5, 2009 at 12:13 PM, Max Rabkin max.rab...@gmail.com wrote: 2009/1/5 Galchin, Vasili vigalc...@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 B.intercalate 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. --Max ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
2009/1/5 Ross Mellgren rmm-hask...@z.odi.ac: 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 intercalate: Or a version of ($) that associates differently. infixl 0 $$ f $$ x = f x *Main Data.ByteString :t \x y z - intercalate $$ intercalate x y $$ z \x y z - intercalate $$ intercalate x y $$ z :: ByteString - [ByteString] - [ByteString] - ByteString -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
Thank you everybody! Vasili On Mon, Jan 5, 2009 at 12:57 PM, David Menendez d...@zednenem.com wrote: 2009/1/5 Ross Mellgren rmm-hask...@z.odi.ac: 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 intercalate: Or a version of ($) that associates differently. infixl 0 $$ f $$ x = f x *Main Data.ByteString :t \x y z - intercalate $$ intercalate x y $$ z \x y z - intercalate $$ intercalate x y $$ z :: ByteString - [ByteString] - [ByteString] - ByteString -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ http://www.eyrie.org/%7Ezednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
On Mon, Jan 5, 2009 at 3:16 PM, Brandon S. Allbery KF8NH allb...@ece.cmu.edu wrote: On 2009 Jan 5, at 13:57, David Menendez wrote: 2009/1/5 Ross Mellgren rmm-hask...@z.odi.ac: 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 intercalate: Or a version of ($) that associates differently. infixl 0 $$ f $$ x = f x *Main Data.ByteString :t \x y z - intercalate $$ intercalate x y $$ z \x y z - intercalate $$ intercalate x y $$ z :: ByteString - [ByteString] - [ByteString] - ByteString ...at which point we're reinventing Applicative, no? Is const a reinvention of return? You could write the above code with (*), but you'd need to convert back and forth from Identity in order to get the proper Applicative instance. runIdentity $ Identity B.intercalate * Identity (B.intercalate x y) * Identity z At that point, you might as well save the noise and write, B.intercalate (B.intercalate x y) z -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] nested function application question
On 2009 Jan 5, at 13:57, David Menendez wrote: 2009/1/5 Ross Mellgren rmm-hask...@z.odi.ac: 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 intercalate: Or a version of ($) that associates differently. infixl 0 $$ f $$ x = f x *Main Data.ByteString :t \x y z - intercalate $$ intercalate x y $ $ z \x y z - intercalate $$ intercalate x y $$ z :: ByteString - [ByteString] - [ByteString] - ByteString ...at which point we're reinventing Applicative, no? -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
