OK, the second question I've sort of answered for myself, by riffing on the
source of line-seq:
(defn expr-seq
"Returns forms from src (assumed to be Clojure source) as a lazy sequence
of expressions"
[^java.io.PushbackReader src]
(when-let [expr (read src)]
(try
(cons expr (lazy-seq (expr-seq src)))
(catch RuntimeException eof))))
However, line-seq doesn't bother with catching an exception (presumably
because it's not using a PushbackReader). So I come back to my first
question: how do I detect the end of a file?
On Monday, 7 April 2014 18:45:44 UTC+1, Simon Brooke wrote:
>
> I've written a pair of functions which read a stream of Clojure source and
> identify the var[*] definitions. They work, but the way they work seems
> clumsy to me. Here they are:
>
> (defn find-vars-in-reader [eddi]
> "Return a list of names of vars declared in the stream this reader
> reads"
> (try
> (let [sexpr (read eddi)]
> (cond
> (nil? sexpr) nil
> (= (first sexpr) 'def) (cons (first (rest
> sexpr)) (find-vars-in-reader eddi))
> true (find-vars-in-reader eddi)))
> (catch RuntimeException eof)))
>
> (defn find-vars-in-file [filename]
> "Return a list of names of vars declared in the file at this path name"
> (with-open [eddi (java.io.PushbackReader. (reader filename))]
> (find-vars-in-reader eddi)))
>
> The thing that really offends me about this is using catching a runtime
> exception to stop reading. There must be a better way of detecting an
> end-of-file, but I've missed it.
>
> The other thing, though, is I can't help feeling that it would be more
> idiomatic Clojure to write a wrapper around a source file which allowed
> functions to treat the file as a lazy sequence of S-expressions; and I can't
> help feeling someone must already have done this. Have they? Is there a
> library I should be looking at?
>
>
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