Re: eval/macros with functions with metadata
I certainly like that better than the binding solution, especially if
hotspot can potentially inline the functions. It still tricky to do
that in a macro, especially when the code to be evaled depends on the
current lexical scope, but I can maybe work around that. Thanks.
On 29 August 2013 04:50, Jason Wolfe ja...@w01fe.com wrote:
Sounds interesting, I'd love to hear more about the use case.
We ran into this issue as well when implementing the new positional
compilation for Graph. We filed a ticket [1], and worked around it with a
funny trick:
Suppose you want to eval a complicated thing, and the crux of the issue is
that this fails:
(let [y 1 f (fn [x] (+ x y))] (eval `(~f 1)))
A solution is to rework what you eval, so that it has a 'hole' for the
function and you slot the function into this hole afterwards (which Hotspot
seems to be able to optimize just fine):
(let [y 1 f (fn [x] (+ x y))] ((eval `(fn [g#] (g# 1))) f))
Happy to elaborate if you like.
Cheers,
Jason
[1] http://dev.clojure.org/jira/browse/CLJ-1206
On Wednesday, August 28, 2013 10:59:19 AM UTC-7, Jamie Brandon wrote:
That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x
... and compile the result ...
strucjure.regression.tests (graph-view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen aa...@assonance.org wrote:
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wol...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the
functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the
call.
What I'd like, though, is for it to be possible to copy the metadata
over to
a new function by client code, just using the regular (with-meta (fn
[blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or
whatever
extra thing, in the metadata, that's used in the form to be eval-ed
is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move,
though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks,
which
may be sweet, aromatic, fermented or spirit-based. ... Family and
social
life also offer numerous other occasions to consume drinks for
pleasure.
[Larousse, Drink entry]
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Re: eval/macros with functions with metadata
what's the use case for evaling a function object?
On Tue, Aug 27, 2013 at 8:54 PM, Ben Wolfson wolf...@gmail.com wrote:
or, the dreaded no matching ctor found exception.
Is there a way to write the function
(defn eval-at-one [f] (eval `(~f 1)))
such that it works when invoked like this:
(eval-at-one (fn [x] x))
;; -- 1
and like this
(eval-at-one (with-meta (fn [x] x) {}))
;; - IllegalArgumentException No matching ctor found for class
clojure.lang.AFunction$1 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
?
I thought that the object returned by with-meta might be hanging onto the
original, metadata-less object, which could then be retrieved and used
without difficulty, but this appears not to be the case.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks, which
may be sweet, aromatic, fermented or spirit-based. ... Family and social
life also offer numerous other occasions to consume drinks for pleasure.
[Larousse, Drink entry]
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(803)-295-0195
fredericksg...@gmail.com
www.gfredericks.com
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Re: eval/macros with functions with metadata
On Wed, Aug 28, 2013 at 2:46 AM, Gary Fredericks fredericksg...@gmail.comwrote: what's the use case for evaling a function object? This is just a minimal example that illustrates the difficulty, in the actual code where I came across it, a new function with relatively complex internals is created at runtime. -- Ben Wolfson Human kind has used its intelligence to vary the flavour of drinks, which may be sweet, aromatic, fermented or spirit-based. ... Family and social life also offer numerous other occasions to consume drinks for pleasure. [Larousse, Drink entry] -- -- 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: eval/macros with functions with metadata
Clojure struggles with staged programming because of JVM limitations. The deeper issue here is that JVM bytecode is fundamentally static: it's not allowed to contain references to objects that only exist at runtime. In languages that have a built-in concept of a runtime image, like Smalltalk or some Lisps, the line between static code and runtime data is blurred. https://groups.google.com/forum/#!searchin/clojure/eval$20closure/clojure/scAjN7_Xig0/bfWuWnzX7z4J https://groups.google.com/forum/#!searchin/clojure/eval$20closure/clojure/eQpeivDn-Vg/Jv29pOd0BgwJ https://groups.google.com/d/topic/clojure/jPGu5MUsGBs/discussion If you aren't worried about leaking memory, a possible workaround is to intern the fn in some namespace and then put the symbol in the macro output. On 28 August 2013 15:17, Ben Wolfson wolf...@gmail.com wrote: On Wed, Aug 28, 2013 at 2:46 AM, Gary Fredericks fredericksg...@gmail.com wrote: what's the use case for evaling a function object? This is just a minimal example that illustrates the difficulty, in the actual code where I came across it, a new function with relatively complex internals is created at runtime. -- Ben Wolfson Human kind has used its intelligence to vary the flavour of drinks, which may be sweet, aromatic, fermented or spirit-based. ... Family and social life also offer numerous other occasions to consume drinks for pleasure. [Larousse, Drink entry] -- -- 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: eval/macros with functions with metadata
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon ja...@scattered-thoughts.net wrote: If you aren't worried about leaking memory, a possible workaround is to intern the fn in some namespace and then put the symbol in the macro output. Hrm, I hope it doesn't come to that---as long as I'm creating the functions with their metadata, I can make things work, because I can add extra information to the with-meta call or do extra things when making the call. What I'd like, though, is for it to be possible to copy the metadata over to a new function by client code, just using the regular (with-meta (fn [blah] blah) (meta old-fn)) mechanism. But then the sneaky symbol, or whatever extra thing, in the metadata, that's used in the form to be eval-ed is pointing to the original function, not the one passed in. Maybe just providing a utility for fixing up the metadata is the right move, though it's kidn of dissatisfying. -- Ben Wolfson Human kind has used its intelligence to vary the flavour of drinks, which may be sweet, aromatic, fermented or spirit-based. ... Family and social life also offer numerous other occasions to consume drinks for pleasure. [Larousse, Drink entry] -- -- 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: eval/macros with functions with metadata
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wolf...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the call.
What I'd like, though, is for it to be possible to copy the metadata over to
a new function by client code, just using the regular (with-meta (fn [blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or whatever
extra thing, in the metadata, that's used in the form to be eval-ed is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move, though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks, which
may be sweet, aromatic, fermented or spirit-based. ... Family and social
life also offer numerous other occasions to consume drinks for pleasure.
[Larousse, Drink entry]
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Re: eval/macros with functions with metadata
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon ja...@scattered-thoughts.net
wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wolf...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the
functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the
call.
What I'd like, though, is for it to be possible to copy the metadata
over to
a new function by client code, just using the regular (with-meta (fn
[blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or whatever
extra thing, in the metadata, that's used in the form to be eval-ed is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move, though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks,
which
may be sweet, aromatic, fermented or spirit-based. ... Family and social
life also offer numerous other occasions to consume drinks for pleasure.
[Larousse, Drink entry]
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Re: eval/macros with functions with metadata
That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x
... and compile the result ...
strucjure.regression.tests (graph-view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen aa...@assonance.org wrote:
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wolf...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the
functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the
call.
What I'd like, though, is for it to be possible to copy the metadata
over to
a new function by client code, just using the regular (with-meta (fn
[blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or whatever
extra thing, in the metadata, that's used in the form to be eval-ed is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move, though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks,
which
may be sweet, aromatic, fermented or spirit-based. ... Family and social
life also offer numerous other occasions to consume drinks for
pleasure.
[Larousse, Drink entry]
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Re: eval/macros with functions with metadata
How about this alternative?
(deftype Wrapper [f]
clojure.lang.IFn
(invoke [this] (f))
(invoke [this a] (f a))
; repeat until you get bored
)
(defn e [f]
(let [wr (Wrapper. f)]
(eval `(~wr 1
(e inc)
(e (with-meta (fn [x] (+ 4 x)) {}))
On Wed, Aug 28, 2013 at 1:59 PM, Jamie Brandon ja...@scattered-thoughts.net
wrote:
That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x
... and compile the result ...
strucjure.regression.tests (graph-view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen aa...@assonance.org wrote:
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wolf...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the
functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the
call.
What I'd like, though, is for it to be possible to copy the metadata
over to
a new function by client code, just using the regular (with-meta (fn
[blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or
whatever
extra thing, in the metadata, that's used in the form to be eval-ed is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move,
though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks,
which
may be sweet, aromatic, fermented or spirit-based. ... Family and
social
life also offer numerous other occasions to consume drinks for
pleasure.
[Larousse, Drink entry]
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Re: eval/macros with functions with metadata
Sorry, that one doesn't work. It worked in my repl, but I must have been
using old code.
On Wed, Aug 28, 2013 at 2:27 PM, Aaron Cohen aa...@assonance.org wrote:
How about this alternative?
(deftype Wrapper [f]
clojure.lang.IFn
(invoke [this] (f))
(invoke [this a] (f a))
; repeat until you get bored
)
(defn e [f]
(let [wr (Wrapper. f)]
(eval `(~wr 1
(e inc)
(e (with-meta (fn [x] (+ 4 x)) {}))
On Wed, Aug 28, 2013 at 1:59 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x
... and compile the result ...
strucjure.regression.tests (graph-view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen aa...@assonance.org wrote:
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wolf...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the
functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the
call.
What I'd like, though, is for it to be possible to copy the metadata
over to
a new function by client code, just using the regular (with-meta (fn
[blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or
whatever
extra thing, in the metadata, that's used in the form to be eval-ed
is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move,
though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks,
which
may be sweet, aromatic, fermented or spirit-based. ... Family and
social
life also offer numerous other occasions to consume drinks for
pleasure.
[Larousse, Drink entry]
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Re: eval/macros with functions with metadata
This is a little hard for me to follow because I'm not sure what graph or
output-in are doing.
If the letfn is being generated by your compilation step, why can't that go
inside of your generated fn rather than outside it?
(clojure.core/fn
[input__2288__auto__]
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(num input__2288__auto__)))
On Wed, Aug 28, 2013 at 1:59 PM, Jamie Brandon ja...@scattered-thoughts.net
wrote:
That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x
... and compile the result ...
strucjure.regression.tests (graph-view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen aa...@assonance.org wrote:
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wolf...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the
functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the
call.
What I'd like, though, is for it to be possible to copy the metadata
over to
a new function by client code, just using the regular (with-meta (fn
[blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or
whatever
extra thing, in the metadata, that's used in the form to be eval-ed is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move,
though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks,
which
may be sweet, aromatic, fermented or spirit-based. ... Family and
social
life also offer numerous other occasions to consume drinks for
pleasure.
[Larousse, Drink entry]
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Re: eval/macros with functions with metadata
Sorry, I guess that wasn't very clear. Let's put a really simple
example with just the pattern-matching subset:
strucjure.regression.sandbox= (def p (pattern [1 ^x _ 3]))
#'strucjure.regression.sandbox/p
strucjure.regression.sandbox= p
[1 #strucjure.pattern.Bind{:symbol x, :pattern #strucjure.pattern.Any{}} 3]
strucjure.regression.sandbox= (def o (output ~p (fnk [x] x)))
#'strucjure.regression.sandbox/o
strucjure.regression.sandbox= o
#strucjure.pattern.Output{:pattern [1 #strucjure.pattern.Bind{:symbol
x, :pattern #strucjure.pattern.Any{}} 3], :fnk #
clojure.lang.AFunction$1@18ab1e1c}
strucjure.regression.sandbox= ((view ~p) [1 2 3])
[[1 2 3] nil]
strucjure.regression.sandbox= ((view ~o) [1 2 3])
[2 nil]
strucjure.regression.sandbox= (pprint (macroexpand-1 '(view ~o)))
(fn
[input3910]
(clojure.core/when
(clojure.core/vector? input3910)
(clojure.core/when
(clojure.core/= (clojure.core/count input3910) 3)
(clojure.core/let
[input-sym3911 (clojure.core/nth input3910 0)]
(clojure.core/when
(clojure.core/= input-sym3911 '1)
(clojure.core/let
[input-sym3912 (clojure.core/nth input3910 1)]
(clojure.core/let
[x input-sym3912]
(clojure.core/let
[input-sym3913 (clojure.core/nth input3910 2)]
(clojure.core/when
(clojure.core/= input-sym3913 '3)
[(#sandbox$fn__3090$pos_fn__1649__auto3091
strucjure.regression.sandbox$fn__3090$pos_fn__1649__auto3091@62b1f96f
x)
(clojure.core/seq (clojure.core/subvec input3910 3))])
You can see towards the end of the generated code where it calls the
fnk directly as #sandbox$fn__3090...
The motivation here is that you can define the grammar for a language
once and then make different transformations by attaching output fnks.
It would be very useful if those output fnks could be closures.
It's not obvious in this small example but the compiler produces some
important optimisations, otherwise I could just interpret the grammar
and there would be no problem.
In general, for staged programming it's useful to be able to pass
arbitrary data between stages eg metaocaml
(http://okmij.org/ftp/ML/MetaOCaml.html) often passes refs between
stages. I think some of the terra (http://terralang.org/) examples
pass closures too.
On 28 August 2013 20:54, Aaron Cohen aa...@assonance.org wrote:
This is a little hard for me to follow because I'm not sure what graph or
output-in are doing.
If the letfn is being generated by your compilation step, why can't that go
inside of your generated fn rather than outside it?
(clojure.core/fn
[input__2288__auto__]
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(num input__2288__auto__)))
On Wed, Aug 28, 2013 at 1:59 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x
... and compile the result ...
strucjure.regression.tests (graph-view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen aa...@assonance.org wrote:
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wolf...@gmail.com wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
Re: eval/macros with functions with metadata
Sounds interesting, I'd love to hear more about the use case.
We ran into this issue as well when implementing the new positional
compilation for Graph. We filed a ticket [1], and worked around it with a
funny trick:
Suppose you want to eval a complicated thing, and the crux of the issue is
that this fails:
(let [y 1 f (fn [x] (+ x y))] (eval `(~f 1)))
A solution is to rework what you eval, so that it has a 'hole' for the
function and you slot the function into this hole afterwards (which Hotspot
seems to be able to optimize just fine):
(let [y 1 f (fn [x] (+ x y))] ((eval `(fn [g#] (g# 1))) f))
Happy to elaborate if you like.
Cheers,
Jason
[1] http://dev.clojure.org/jira/browse/CLJ-1206
On Wednesday, August 28, 2013 10:59:19 AM UTC-7, Jamie Brandon wrote:
That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x
... and compile the result ...
strucjure.regression.tests (graph-view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen aa...@assonance.org javascript:
wrote:
I'm not sure if you'll consider this hacky or not.
(def ^:dynamic *fn-helper*)
(defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1
On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
ja...@scattered-thoughts.net javascript: wrote:
You will also run into problems if your functions close over any data:
user (let [f (fn [] 1)] (eval `(~f)))
1
nil
user (let [x 1 f (fn [] x)] (eval `(~f)))
IllegalArgumentException No matching ctor found for class
user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
I'm struggling with this as well, I'm definitely interested in finding
a non-hacky way to pass closures through eval without leaking memory.
Perhaps something like:
(let [x 1
f (fn [] x)
f-sym (gensym)]
(intern *ns* gensym (weak-ref f))
(with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
So that way f will be freed up when the resulting fn is gced.
On 28 August 2013 17:59, Ben Wolfson wol...@gmail.com javascript:
wrote:
On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
ja...@scattered-thoughts.net javascript: wrote:
If you aren't worried about leaking memory, a possible workaround is
to intern the fn in some namespace and then put the symbol in the
macro output.
Hrm, I hope it doesn't come to that---as long as I'm creating the
functions
with their metadata, I can make things work, because I can add extra
information to the with-meta call or do extra things when making the
call.
What I'd like, though, is for it to be possible to copy the metadata
over to
a new function by client code, just using the regular (with-meta (fn
[blah]
blah) (meta old-fn)) mechanism. But then the sneaky symbol, or
whatever
extra thing, in the metadata, that's used in the form to be eval-ed
is
pointing to the original function, not the one passed in. Maybe just
providing a utility for fixing up the metadata is the right move,
though
it's kidn of dissatisfying.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks,
which
may be sweet, aromatic, fermented or spirit-based. ... Family and
social
life also offer numerous other occasions to consume drinks for
pleasure.
[Larousse, Drink entry]
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You received this message because you are
eval/macros with functions with metadata
or, the dreaded no matching ctor found exception.
Is there a way to write the function
(defn eval-at-one [f] (eval `(~f 1)))
such that it works when invoked like this:
(eval-at-one (fn [x] x))
;; -- 1
and like this
(eval-at-one (with-meta (fn [x] x) {}))
;; - IllegalArgumentException No matching ctor found for class
clojure.lang.AFunction$1 clojure.lang.Reflector.invokeConstructor
(Reflector.java:163)
?
I thought that the object returned by with-meta might be hanging onto the
original, metadata-less object, which could then be retrieved and used
without difficulty, but this appears not to be the case.
--
Ben Wolfson
Human kind has used its intelligence to vary the flavour of drinks, which
may be sweet, aromatic, fermented or spirit-based. ... Family and social
life also offer numerous other occasions to consume drinks for pleasure.
[Larousse, Drink entry]
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