doseq is a macro, not a function, and its expansion expands the loop right
in place :
$ java -cp clojure/clojure.jar:clojure-contrib/clojure-contrib.jar
clojure.contrib.repl_ln
Clojure 1.1.0-master-SNAPSHOT
1:1 user=> (require 'clojure.contrib.pprint)
nil
1:2 user=> (clojure.contrib.pprint/pprint (macroexpand-1 '(doseq [x (range 0
10)] x)))
(clojure.core/loop
[seq_9
(clojure.core/seq (range 0 10))
chunk_10
nil
count_11
(clojure.core/int 0)
i_12
(clojure.core/int 0)]
(if
(clojure.core/< i_12 count_11)
(clojure.core/let
[x (.nth chunk_10 i_12)]
(do x)
(recur seq_9 chunk_10 count_11 (clojure.core/unchecked-inc i_12)))
(clojure.core/when-let
[seq_9 (clojure.core/seq seq_9)]
(if
(clojure.core/chunked-seq? seq_9)
(clojure.core/let
[c__5257__auto__ (clojure.core/chunk-first seq_9)]
(recur
(clojure.core/chunk-rest seq_9)
c__5257__auto__
(clojure.core/int (clojure.core/count c__5257__auto__))
(clojure.core/int 0)))
(clojure.core/let
[x (clojure.core/first seq_9)]
(do x)
(recur
(clojure.core/next seq_9)
nil
(clojure.core/int 0)
(clojure.core/int 0)))))))
nil
1:3 user=>
HTH,
--
Laurent
2009/12/15 Greg Harman <ghar...@gmail.com>
> Why does that work? The same recursion happens in the finally. There's
> a layer of indirection now, but the doseq was already a layer of
> indirection between the finally and doseq's internal recur.
>
> I see from the linked thread above that the basic issue is a known
> implementation issue with Clojure to limit complexity - given that,
> perhaps doseq (and any other out-of-the-box macros/functions that are
> internally implemented with recur, or otherwise trigger that
> exception) should be documented as having this effect.
>
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