Re: monads m-seq and m-lift
As I understand it, m-seq is transforms a list of monadic computation into a computation returning the list of result. The resulting computation just sequentially does every computationin the sequence and keep the result. It is useful when the arity is not known at runtime foir example. On Tue, Nov 2, 2010 at 10:45 AM, Sunil S Nandihalli sunil.nandiha...@gmail.com wrote: Hello everybody, I was looking at the functions/macros defined with them I find that m-lift is very easy and intuitive .. following is the extract from the monads example ... (with-monad sequence-m (defn pairs [xs] ((m-lift 4 #(list :a %1 :b %2 :c %3 :d %4)) (range 0 3) (range 10 13) (range 100 103) (range 1000 1003 (pairs (range 2)) ; Another way to define pairs is through the m-seq operation. It takes ; a sequence of monadic values and returns a monadic value containing ; the sequence of the underlying values, obtained from chaining together ; from left to right the monadic values in the sequence. (with-monad sequence-m (defn pairs [xs] (m-seq (list xs xs can somebody help me understand what is happening in the second one .. ? when would it be more appropriate to use m-seq instead of m-lift .. Thanks, Sunil. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- Sent from an IBM Model M, 15 August 1989. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: monads m-seq and m-lift
On 02.11.2010, at 11:45, Sunil S Nandihalli wrote: following is the extract from the monads example ... It looks quite modified and no longer returns pairs! Here is the original: (with-monad sequence-m (defn pairs [xs] ((m-lift 2 #(list %1 %2)) xs xs))) ; Another way to define pairs is through the m-seq operation. It takes ; a sequence of monadic values and returns a monadic value containing ; the sequence of the underlying values, obtained from chaining together ; from left to right the monadic values in the sequence. (with-monad sequence-m (defn pairs [xs] (m-seq (list xs xs can somebody help me understand what is happening in the second one .. ? when would it be more appropriate to use m-seq instead of m-lift .. In most real-life cases you wouldn't have that choice, as m-lift and m-seq do very different things. It's just for making pairs that either one is fine. One example for the use of m-seq is given right after the pairs example: (with-monad sequence-m (defn ntuples [n xs] (m-seq (replicate n xs This is a generalization from pairs to n-tuples. You couldn't do this using m-lift applied to the list function because m-lift requires a fixed arity. Another example is given later in the example collection under random number generators. Konrad. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: monads m-seq and m-lift
On Tue, Nov 2, 2010 at 7:58 AM, Konrad Hinsen konrad.hin...@fastmail.netwrote: On 02.11.2010, at 11:45, Sunil S Nandihalli wrote: following is the extract from the monads example ... It looks quite modified and no longer returns pairs! Here is the original: (with-monad sequence-m (defn pairs [xs] ((m-lift 2 #(list %1 %2)) xs xs))) ; Another way to define pairs is through the m-seq operation. It takes ; a sequence of monadic values and returns a monadic value containing ; the sequence of the underlying values, obtained from chaining together ; from left to right the monadic values in the sequence. (with-monad sequence-m (defn pairs [xs] (m-seq (list xs xs can somebody help me understand what is happening in the second one .. ? when would it be more appropriate to use m-seq instead of m-lift .. In most real-life cases you wouldn't have that choice, as m-lift and m-seq do very different things. It's just for making pairs that either one is fine. One example for the use of m-seq is given right after the pairs example: (with-monad sequence-m (defn ntuples [n xs] (m-seq (replicate n xs This is a generalization from pairs to n-tuples. You couldn't do this using m-lift applied to the list function because m-lift requires a fixed arity. This wouldn't work?: (with-monad sequence-m (defn ntuples [n xs] (apply (m-lift n list) (replicate n xs (If m-lift is a macro that requires the arity arg to be known at macroexpansion time: (with-monad sequence-m (defn ntuples [n xs] (apply (eval `(m-lift ~n list)) (replicate n xs instead. Icky, mind you.) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: monads m-seq and m-lift
On 02.11.2010, at 13:34, Ken Wesson wrote: This wouldn't work?: (with-monad sequence-m (defn ntuples [n xs] (apply (m-lift n list) (replicate n xs No. (If m-lift is a macro that requires the arity arg to be known at macroexpansion time: (with-monad sequence-m (defn ntuples [n xs] (apply (eval `(m-lift ~n list)) (replicate n xs instead. Icky, mind you.) That should work. But once you are at that level of Lisp proficiency, you should also have heard the eval is evil lesson a few times ;-) Konrad. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: monads m-seq and m-lift
On Tue, Nov 2, 2010 at 8:55 AM, Konrad Hinsen konrad.hin...@fastmail.netwrote: On 02.11.2010, at 13:34, Ken Wesson wrote: This wouldn't work?: (with-monad sequence-m (defn ntuples [n xs] (apply (m-lift n list) (replicate n xs No. (If m-lift is a macro that requires the arity arg to be known at macroexpansion time: (with-monad sequence-m (defn ntuples [n xs] (apply (eval `(m-lift ~n list)) (replicate n xs instead. Icky, mind you.) That should work. But once you are at that level of Lisp proficiency, you should also have heard the eval is evil lesson a few times ;-) Yeah, I wouldn't actually use it for something like that in production code. In this case I'd use m-seq. In fact the only time I've used eval in production code, thus far, was in a system that had to generate new functions on the fly based on data only available at runtime, and for efficiency reasons those needed to become bytecode and potentially subject to JIT compilation. So there was a compiler function that took some data, constructed (fn ...) forms and eval'd them, and returned the resulting function objects to its caller. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: monads m-seq and m-lift
Hi Konrad, nicolas and Ken, Thanks for help. I am sure I will need more help when I try to walk through the rest of the examples. But the idea of monads is really neat..:).. Sunil. On Tue, Nov 2, 2010 at 7:19 PM, Ken Wesson kwess...@gmail.com wrote: On Tue, Nov 2, 2010 at 8:55 AM, Konrad Hinsen konrad.hin...@fastmail.netwrote: On 02.11.2010, at 13:34, Ken Wesson wrote: This wouldn't work?: (with-monad sequence-m (defn ntuples [n xs] (apply (m-lift n list) (replicate n xs No. (If m-lift is a macro that requires the arity arg to be known at macroexpansion time: (with-monad sequence-m (defn ntuples [n xs] (apply (eval `(m-lift ~n list)) (replicate n xs instead. Icky, mind you.) That should work. But once you are at that level of Lisp proficiency, you should also have heard the eval is evil lesson a few times ;-) Yeah, I wouldn't actually use it for something like that in production code. In this case I'd use m-seq. In fact the only time I've used eval in production code, thus far, was in a system that had to generate new functions on the fly based on data only available at runtime, and for efficiency reasons those needed to become bytecode and potentially subject to JIT compilation. So there was a compiler function that took some data, constructed (fn ...) forms and eval'd them, and returned the resulting function objects to its caller. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.comclojure%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: monads m-seq and m-lift
yea .. I was playing around and modified it in the due coarse.. :) Sunil. On Tue, Nov 2, 2010 at 5:28 PM, Konrad Hinsen konrad.hin...@fastmail.netwrote: On 02.11.2010, at 11:45, Sunil S Nandihalli wrote: following is the extract from the monads example ... It looks quite modified and no longer returns pairs! Here is the original: (with-monad sequence-m (defn pairs [xs] ((m-lift 2 #(list %1 %2)) xs xs))) ; Another way to define pairs is through the m-seq operation. It takes ; a sequence of monadic values and returns a monadic value containing ; the sequence of the underlying values, obtained from chaining together ; from left to right the monadic values in the sequence. (with-monad sequence-m (defn pairs [xs] (m-seq (list xs xs can somebody help me understand what is happening in the second one .. ? when would it be more appropriate to use m-seq instead of m-lift .. In most real-life cases you wouldn't have that choice, as m-lift and m-seq do very different things. It's just for making pairs that either one is fine. One example for the use of m-seq is given right after the pairs example: (with-monad sequence-m (defn ntuples [n xs] (m-seq (replicate n xs This is a generalization from pairs to n-tuples. You couldn't do this using m-lift applied to the list function because m-lift requires a fixed arity. Another example is given later in the example collection under random number generators. Konrad. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.comclojure%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
