* Re: [Caml-list] Good examples for a Camlp4 beginner?
2003-05-30 18:52 [Caml-list] Good examples for a Camlp4 beginner? Matt Gushee
@ 2003-05-30 19:13 ` Alexander V. Voinov
2003-05-30 19:27 ` Matt Gushee
2003-05-30 20:13 ` Basile STARYNKEVITCH
1 sibling, 1 reply; 4+ messages in thread
From: Alexander V. Voinov @ 2003-05-30 19:13 UTC (permalink / raw)
To: Matt Gushee; +Cc: caml-list
[-- Attachment #1: Type: text/plain, Size: 807 bytes --]
Hi Matt,
See a simple extension, which adds some sugar on top of the List module
functionality. My purpose in this case was to give close analogs to
Python's loops over sequences (e.g. lists), to facilitate transition. An
example is attached as well.
Alexander
Matt Gushee wrote:
>Hello, all--
>
>Over the past couple of weeks I have been learning about the various
>OCaml parsing and lexing tools, with an emphasis on Camlp4. It's
>fascinating, and I've learned a lot, but I am still having trouble
>grasping how the different components fit together. I think what I need
>now is to look at some examples of working, real-world code that use
>Camlp4 ... something non-trivial, but not enormously complex. Can anyone
>suggest a good place to start?
>
>Thanks in advance for any suggestions.
>
>
>
[-- Attachment #2: listsugar.ml --]
[-- Type: text/plain, Size: 957 bytes --]
open Pcaml;;
EXTEND
GLOBAL: expr;
expr:
[ [ "map"; list = expr; "with"; OPT "|"; clauses = LIST1 clause SEP "|" ->
<:expr< List.map (fun [ $list:clauses$ ]) $list$ >> ]
| [ "iterate"; list = expr; "with"; OPT "|"; clauses = LIST1 clause SEP "|" ->
<:expr< List.iter (fun [ $list:clauses$ ]) $list$ >> ]
| [ "foldr"; list = expr; "from"; initval = expr; "with"; OPT "|";
clauses = LIST1 clause SEP "|" ->
<:expr< List.fold_right (fun a b ->
match (a, b) with [ $list:clauses$ ])
$list$ $initval$ >> ]
| [ "foldl"; list = expr; "from"; initval = expr; "with"; OPT "|";
clauses = LIST1 clause SEP "|" ->
<:expr< List.fold_left (fun a b ->
match (a, b) with [ $list:clauses$ ])
$initval$ $list$ >> ]
];
clause:
[[ p = patt; w = OPT when_expr; "->"; e = expr -> (p, w, e)]];
when_expr:
[[ "when"; e = expr -> e ]];
END;;
[-- Attachment #3: testsugar.ml --]
[-- Type: text/plain, Size: 973 bytes --]
open Printf
let _ =
let values = [1; 2; 3; 4; 5; 6; 7] in
let vals2 =
map values with
| 1 | 3 | 7 -> 10
| v when v mod 2 == 0 -> v + 1
| v -> v - 1
in
let valfmtd = String.concat ", " (map vals2 with v -> sprintf "<%d>" v) in
let suml, sumsquares, nelem =
foldl values from 0.0, 0.0, 0 with
(suml0, sumsq0, n), value ->
let fv = float value in
(suml0 +. fv, sumsq0 +. fv *. fv, n + 1)
in
let mean = suml /. float nelem in
let sdev = sqrt ((sumsquares -. float nelem *. mean *. mean)
/. (float nelem -. 1.0)) in
let sumr =
foldr values from 0.0 with
value, sum0 -> (
printf "found value = %d, sum0 = %5.2f\n" value sum0;
sum0 +. float value
)
in
printf "%s\n" valfmtd;
printf "mean: %g, sdev: %g\n" mean sdev;
printf "sumr: %g\n" sumr;
iterate values with
| 1 -> printf "one\n"
| v when v mod 2 == 0 -> printf "%d is even\n" v
| v -> printf "%d is odd\n" v
^ permalink raw reply [flat|nested] 4+ messages in thread* [Caml-list] Good examples for a Camlp4 beginner?
2003-05-30 18:52 [Caml-list] Good examples for a Camlp4 beginner? Matt Gushee
2003-05-30 19:13 ` Alexander V. Voinov
@ 2003-05-30 20:13 ` Basile STARYNKEVITCH
1 sibling, 0 replies; 4+ messages in thread
From: Basile STARYNKEVITCH @ 2003-05-30 20:13 UTC (permalink / raw)
To: Matt Gushee; +Cc: caml-list
>>>>> "Matt" == Matt Gushee <mgushee@havenrock.com> writes:
Matt> Hello, all-- Over the past couple of weeks I have been
Matt> learning about the various OCaml parsing and lexing tools,
Matt> with an emphasis on Camlp4. It's fascinating, and I've
Matt> learned a lot, but I am still having trouble grasping how
Matt> the different components fit together. I think what I need
Matt> now is to look at some examples of working, real-world code
Matt> that use Camlp4 ... something non-trivial, but not
Matt> enormously complex. Can anyone suggest a good place to
Matt> start?
Yes, you might look into the tracing facilities of Poesia monitor;
get the following files (under CVS) from
http://www2.poesia-filter.org:8000/cgi-bin/cvsweb.cgi/PoesiaSoft/PoesiaMonIcap/
README.trace
pa_trace.ml
trace.ml
trace.mli
In a few words, the pa_trace.ml preprocessing file transform
expressions like
trace FOO "x=%d y=%d" x y tracend
into
begin
if Trace.flags.foo then
Trace.tracer Trace.FOO [filename] [lineno] [colno]
(Printf.sprintf "x=%d y=%d" x y
end
where [filename] is actually the string of the source filename, eg
"foobar.ml", [lineno] is the line number, eg 43, etc.
Even if I coded some camlp4 stuff, I definitely do not claim to be a
camlp4 expert. In particular, I never coded any pretty printer.
Of course you could have a look into the Coq proof system, which
(IIRC) initated the development of camlp4 and which is probably the
major camlp4 user.
Regards.
--
Basile STARYNKEVITCH http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net
aliases: basile<at>tunes<dot>org = bstarynk<at>nerim<dot>net
8, rue de la Faïencerie, 92340 Bourg La Reine, France
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^ permalink raw reply [flat|nested] 4+ messages in thread