Thread Macro For Inserting In Arbitrary Positions
Frequently I want to use the thread macros (- or -) except I need
to thread the arguments into positions other than the first and the
last. Or sometimes I have to go back and forth between first and last
positions. Instead of alternating between - and - and creating
nesting, I've been using this thread macro which replaces underscore
with the value of the previous expression.
(defmacro --
Threads the expr through the forms. Replaces all underscores (_)
with x in the form, making a list of it if it is not a list already.
If there are more forms, inserts the first form as the last item in
second form, etc.
([x form] (if (seq? form)
(with-meta `(~(first form) ~@(replace {'_ x} (next
form))) (meta form))
(list form x)))
([x form more] `(-- (-- ~x ~form) ~@more)))
Is there a reason something like this does not exist in clojure.core?
Is this an oversight or is there a reason this is not there?
Asim
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Re: Thread Macro For Inserting In Arbitrary Positions
Here is an example of using this:
(-- hello world (.toUpperCase _) (.toLowerCase _) (.indexOf _ w))
On Tue, Jul 5, 2011 at 3:50 PM, Asim Jalis asimja...@gmail.com wrote:
Frequently I want to use the thread macros (- or -) except I need
to thread the arguments into positions other than the first and the
last. Or sometimes I have to go back and forth between first and last
positions. Instead of alternating between - and - and creating
nesting, I've been using this thread macro which replaces underscore
with the value of the previous expression.
(defmacro --
Threads the expr through the forms. Replaces all underscores (_)
with x in the form, making a list of it if it is not a list already.
If there are more forms, inserts the first form as the last item in
second form, etc.
([x form] (if (seq? form)
(with-meta `(~(first form) ~@(replace {'_ x} (next
form))) (meta form))
(list form x)))
([x form more] `(-- (-- ~x ~form) ~@more)))
Is there a reason something like this does not exist in clojure.core?
Is this an oversight or is there a reason this is not there?
Asim
--
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To post to this group, send email to clojure@googlegroups.com
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Re: Thread Macro For Inserting In Arbitrary Positions
Is there a reason something like this does not exist in clojure.core?
Is this an oversight or is there a reason this is not there?
Previous discussions on this subject:
1.
http://groups.google.com/group/clojure/browse_thread/thread/e826fc303e440b7c/0e7bdba707b7982d
(in particular Rich's response on the second page:
http://groups.google.com/group/clojure/msg/1eb5cf8fa3248049 )
2.
http://groups.google.com/group/clojure/browse_thread/thread/66ff0b89229be894/c3d4a6dae45d4852
On Tue, Jul 5, 2011 at 7:14 PM, Asim Jalis asimja...@gmail.com wrote:
Here is an example of using this:
(-- hello world (.toUpperCase _) (.toLowerCase _) (.indexOf _ w))
On Tue, Jul 5, 2011 at 3:50 PM, Asim Jalis asimja...@gmail.com wrote:
Frequently I want to use the thread macros (- or -) except I need
to thread the arguments into positions other than the first and the
last. Or sometimes I have to go back and forth between first and last
positions. Instead of alternating between - and - and creating
nesting, I've been using this thread macro which replaces underscore
with the value of the previous expression.
(defmacro --
Threads the expr through the forms. Replaces all underscores (_)
with x in the form, making a list of it if it is not a list already.
If there are more forms, inserts the first form as the last item in
second form, etc.
([x form] (if (seq? form)
(with-meta `(~(first form) ~@(replace {'_ x} (next
form))) (meta form))
(list form x)))
([x form more] `(-- (-- ~x ~form) ~@more)))
Is there a reason something like this does not exist in clojure.core?
Is this an oversight or is there a reason this is not there?
Asim
--
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your first post.
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--
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Re: Thread Macro For Inserting In Arbitrary Positions
On Tue, Jul 5, 2011 at 4:14 PM, Asim Jalis asimja...@gmail.com wrote: Here is an example of using this: (-- hello world (.toUpperCase _) (.toLowerCase _) (.indexOf _ w)) BTW, that's not a very compelling example since you can already do: (- hello world! .toUpperCase .toLowerCase (.indexOf w)) -- Sean A Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org/ World Singles, LLC. -- http://worldsingles.com/ Railo Technologies, Inc. -- http://www.getrailo.com/ Perfection is the enemy of the good. -- Gustave Flaubert, French realist novelist (1821-1880) -- 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
