Re: cond- variant?
I wrote pred-cond for Midje way back, which does what you want. https://github.com/marick/Midje/blob/master/src/midje/clojure/core.clj#L176 Example use: https://github.com/marick/Midje/blob/master/src/midje/parsing/1_to_explicit_form/facts.clj#L100 Like normal cond pred-cond will short-circuit once it hits a match (so unlike con-) On Tue, Feb 11, 2014 at 11:36 PM, s...@corfield.org wrote: I use cond- quite a lot but I find myself often wanting a version that uses predicate functions rather than expressions which would seem more “threaded”. Am I just missing a better way to write these things? For example: (cond- accounts (empty? accounts) (conj “stuff”)) That just screams for something like: (condp- accounts empty? (conj “stuff”)) Then you could thread the predicates: (condp- a p1 (f1 args) p2 (f2 args)) which would be: (let [x (if (p1 a) (f1 a args) a)] (if (p2 x) (f2 x args) x)) Suggestions? Sean Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org World Singles, LLC - http://worldsingles.com -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out. -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: cond- variant?
On Feb 12, 2014, at 1:34 AM, Alex Baranosky alexander.barano...@gmail.com wrote: I wrote pred-cond for Midje way back, which does what you want. https://github.com/marick/Midje/blob/master/src/midje/clojure/core.clj#L176 That doesn't appear to thread each expression through the results so it isn't really a variant of cond- but between that and the source of cond- I suspect I will just end up rolling my own... Sean Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org/ Perfection is the enemy of the good. -- Gustave Flaubert, French realist novelist (1821-1880) signature.asc Description: Message signed with OpenPGP using GPGMail
Re: cond- variant?
Here's what I ended up with - minor variants of cond- and cond- (defmacro condp- Takes an expression and a set of predicate/form pairs. Threads expr (via -) through each form for which the corresponding predicate is true of expr. Note that, unlike cond branching, condp- threading does not short circuit after the first true test expression. [expr clauses] (assert (even? (count clauses))) (let [g (gensym) pstep (fn [[pred step]] `(if (~pred ~g) (- ~g ~step) ~g))] `(let [~g ~expr ~@(interleave (repeat g) (map pstep (partition 2 clauses)))] ~g))) (defmacro condp- Takes an expression and a set of predicate/form pairs. Threads expr (via -) through each form for which the corresponding predicate is true of expr. Note that, unlike cond branching, condp- threading does not short circuit after the first true test expression. [expr clauses] (assert (even? (count clauses))) (let [g (gensym) pstep (fn [[pred step]] `(if (~pred ~g) (- ~g ~step) ~g))] `(let [~g ~expr ~@(interleave (repeat g) (map pstep (partition 2 clauses)))] ~g))) On Feb 12, 2014, at 2:34 PM, Sean Corfield s...@corfield.org wrote: On Feb 12, 2014, at 1:34 AM, Alex Baranosky alexander.barano...@gmail.com wrote: I wrote pred-cond for Midje way back, which does what you want. https://github.com/marick/Midje/blob/master/src/midje/clojure/core.clj#L176 That doesn't appear to thread each expression through the results so it isn't really a variant of cond- but between that and the source of cond- I suspect I will just end up rolling my own... signature.asc Description: Message signed with OpenPGP using GPGMail
cond- variant?
I use cond- quite a lot but I find myself often wanting a version that uses predicate functions rather than expressions which would seem more “threaded”. Am I just missing a better way to write these things? For example: (cond- accounts (empty? accounts) (conj “stuff”)) That just screams for something like: (condp- accounts empty? (conj “stuff”)) Then you could thread the predicates: (condp- a p1 (f1 args) p2 (f2 args)) which would be: (let [x (if (p1 a) (f1 a args) a)] (if (p2 x) (f2 x args) x)) Suggestions? Sean Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org World Singles, LLC - http://worldsingles.com -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
