On Sun, Jun 05, 2016 at 10:37:12PM +0200, Ludovic Courtès wrote: > Efraim Flashner <efr...@flashner.co.il> skribis: > > + > > +(define* (wc-command-implementation file #:optional args) > > + (let-values (((lines chars) > > + (call-with-input-file file lines+chars))) > > + (match args > > + (#\l > > + (format #t "~a ~a~%" lines file)) > > + (#\c > > + (format #t "~a ~a~%" chars file)) > > + (_ > > + (format #t "~a ~a ~a~%" lines chars file))))) > > + > > +(define (wc-command args . rest) > > + (let* ((flags (cond ((string=? args "-l") #\l) > > + ((string=? args "-c") #\c) > > + (else #\nul))) ; no flags, "args" is a file > > + (files (filter (lambda (file) > > + (catch 'system-error > > + (lambda () > > + (lstat file)) > > + (lambda args > > + (let ((errno (system-error-errno args))) > > + (format (current-error-port) "~a: ~a~%" > > + file (strerror errno)) > > + #f)))) > > + (if (char=? flags #\nul) (cons args rest) rest)))) > > + (for-each > > + (lambda (file) > > + ((@@ (guix build bournish) wc-command-implementation) file flags)) > > + files))) > > As discussed at > <https://lists.gnu.org/archive/html/guix-devel/2016-05/msg00782.html>, > remember that ‘wc-command’ is called by the compiler to generate Scheme > code from the input shell code. Thus, it must emit code that does the > job. However, here, it does the job directly, at compilation time, and > emits the result of ‘for-each’ as code.
copied from that email: Thus, you must similarly distinguish those two stages by providing: 1. A ‘wc-command-implementation’ procedure that implements ‘wc’; 2. A ‘wc-command’ procedure that emits the code that calls wc-command-implementation’; so something like: (define (wc-command args) `((@@ (guix build bournish) wc-command-implementation) ,@args)) Better yet, ‘wc-command’ could check for the presence of “-l” or “-c” at compile time and emit a call to the right thing. > > I’ll commit a couple of fixes for bugs I just found and that prevent us > from doing: > > (compile "ls" #:from %bournish-language #:to 'scheme). > > This is useful to clearly understand what code is generated from the > input. > > Ludo’. I've refactored the code so now in wc-command it checks if theres a flag or not, and then passes the list of files to wc-command-implementation to do the actual computation. Does it make sense to switch it to something like the case-lambda setup that `ls' uses or is for-each ok? -- Efraim Flashner <efr...@flashner.co.il> אפרים פלשנר GPG key = A28B F40C 3E55 1372 662D 14F7 41AA E7DC CA3D 8351 Confidentiality cannot be guaranteed on emails sent or received unencrypted
From ebce5076177314bfd17a53019b3f6b6888762b01 Mon Sep 17 00:00:00 2001
From: Efraim Flashner <efr...@flashner.co.il>
Date: Sun, 22 May 2016 14:56:06 +0300
Subject: [PATCH] bournish: Add `wc' command.
* guix/build/bournish.scm (file-size, wc-c-command, wc-l-command,
lines+chars, wc-command, wc-command-implementation): New variables.
(%commands): Add wc command.
---
guix/build/bournish.scm | 64 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 63 insertions(+), 1 deletion(-)
diff --git a/guix/build/bournish.scm b/guix/build/bournish.scm
index 1f17e0a..46e6e1c 100644
--- a/guix/build/bournish.scm
+++ b/guix/build/bournish.scm
@@ -1,5 +1,6 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016 Ludovic Courtès <l...@gnu.org>
+;;; Copyright © 2016 Efraim Flashner <efr...@flashner.co.il>
;;;
;;; This file is part of GNU Guix.
;;;
@@ -25,7 +26,9 @@
#:use-module (ice-9 match)
#:use-module (ice-9 ftw)
#:use-module (srfi srfi-1)
+ #:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
+ #:use-module (srfi srfi-41)
#:export (%bournish-language))
;;; Commentary:
@@ -103,6 +106,64 @@ characters."
((@ (guix build utils) dump-port) port (current-output-port))
*unspecified*)))
+(define (file-size file)
+ (stat:size (stat file)))
+
+(define (wc-c-command file)
+ ;; Faster when only `wc -c' is called
+ (file-size file))
+
+(define (wc-l-command file)
+ ;; Faster when only `wc -l' is called
+ (stream-length
+ (stream-filter
+ (lambda (chr)
+ (char=? chr #\newline))
+ (port->stream (open-file file "r")))))
+
+(define (lines+chars port)
+ ;; Return the number of lines and number of chars read from PORT.
+ ;; TODO: Also return the number of words.
+ (let loop ((lines 0) (chars 0))
+ (match (read-char port) ; get the next char ready
+ ((? eof-object?) ;done!
+ (values lines chars))
+ (#\newline ;recurse
+ (loop (1+ lines) (1+ chars)))
+ (_ ;recurse
+ (loop lines (1+ chars))))))
+
+(define* (wc-command-implementation filelist #:optional args)
+ (let ((files (filter (lambda (file)
+ (catch 'system-error
+ (lambda ()
+ (lstat file))
+ (lambda args
+ (let ((errno (system-error-errno args)))
+ (format (current-error-port) "~a: ~a~%"
+ file (strerror errno))
+ #f))))
+ filelist)))
+ (for-each
+ (lambda (file)
+ (let-values (((lines chars)
+ (call-with-input-file file lines+chars)))
+ (match args
+ (#\l
+ (format #t "~a ~a~%" lines file))
+ (#\c
+ (format #t "~a ~a~%" chars file))
+ (_
+ (format #t "~a ~a ~a~%" lines chars file)))))
+ files)))
+
+(define (wc-command args . rest)
+ (let* ((flags (cond ((string=? args "-l") #\l)
+ ((string=? args "-c") #\c)
+ (else #\nul)))) ; no flags, "args" is a file
+ ((@@ (guix build bournish) wc-command-implementation)
+ (if (char=? flags #\nul) (cons args rest) rest) flags)))
+
(define (help-command . _)
(display "\
Hello, this is Bournish, a minimal Bourne-like shell in Guile!
@@ -129,7 +190,8 @@ commands such as 'ls' and 'cd'; it lacks globbing,
pipes---everything.\n"))
("help" ,help-command)
("ls" ,ls-command)
("which" ,which-command)
- ("cat" ,cat-command)))
+ ("cat" ,cat-command)
+ ("wc" ,wc-command)))
(define (read-bournish port env)
"Read a Bournish expression from PORT, and return the corresponding Scheme
--
2.8.3
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