On Tue, Jun 14, 2016 at 01:20:29PM +0300, Efraim Flashner wrote: > On Tue, Jun 14, 2016 at 11:57:26AM +0200, Ricardo Wurmus wrote: > > > > Efraim Flashner <[email protected]> writes: > > > > > +(define wc-command-implementation > > > + (lambda files > > > + (let ((files (filter (lambda (file) > > > + (catch 'system-error > > > + (lambda () > > > + (stat file)) > > > + (lambda args > > > + (let ((errno (system-error-errno args))) > > > + (format (current-error-port) "~a: ~a~%" > > > + file (strerror errno)) > > > + #f)))) > > > + files))) > > > + (for-each > > > + (lambda (file) > > > + (let-values (((lines chars) > > > + (call-with-input-file file lines+chars))) > > > + (format #t "~a ~a ~a~%" lines chars file))) > > > + files)))) > > > + > > > +(define wc-l-command-implementation > > > + (lambda files > > > + (let ((files (filter (lambda (file) > > > + (catch 'system-error > > > + (lambda () > > > + (stat file)) > > > + (lambda args > > > + (let ((errno (system-error-errno args))) > > > + (format (current-error-port) "~a: ~a~%" > > > + file (strerror errno)) > > > + #f)))) > > > + files))) > > > + (for-each > > > + (lambda (file) > > > + (let-values (((lines chars) > > > + (call-with-input-file file lines+chars))) > > > + (format #t "~a ~a~%" lines file))) > > > + files)))) > > > + > > > +(define wc-c-command-implementation > > > + (lambda files > > > + (let ((files (filter (lambda (file) > > > + (catch 'system-error > > > + (lambda () > > > + (stat file)) > > > + (lambda args > > > + (let ((errno (system-error-errno args))) > > > + (format (current-error-port) "~a: ~a~%" > > > + file (strerror errno)) > > > + #f)))) > > > + files))) > > > + (for-each > > > + (lambda (file) > > > + (let-values (((lines chars) > > > + (call-with-input-file file lines+chars))) > > > + (format #t "~a ~a~%" chars file))) > > > + files)))) > > > > It looks to me that the filter function is the same in all of these > > procedures. Even the actual implementation, i.e. the for-each over the > > resulting files is almost exactly the same. > > > > This could be simplified. If only the format expression differs then > > you could abstract this difference away. You could still have three > > different procedures, but they can be the result of evaluating a > > higher-order function. > > > > It also seems to me that you could use syntactic sugar to simplify > > “(define something (lambda ...))” to “(define (something ...))”. > > > > ~~ Ricardo > > It's already calling `((@@ (guix build bournish) > wc-l-command-implementation) ,@(delete "-l" args)), I could try changing > the ,@(delete part to ,@((@@ (guix build bournish) only-files) ,@(delete > "-l" args)) and then the various implementation functions will be just > printing the results >
It turns out I forgot that calling only-files from wc-commands would make it evaluate too soon, so I stuck it inside the different implementations. Factoring out the check if a file exists or not could also apply to the ls-command-implementation too later. -- Efraim Flashner <[email protected]> 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 09eef9cd841a7d212e024be0609168611923696b Mon Sep 17 00:00:00 2001 From: Efraim Flashner <[email protected]> Date: Sun, 22 May 2016 14:56:06 +0300 Subject: [PATCH] bournish: Add `wc' command. * guix/build/bournish.scm (lines+chars, only-files, wc-commands, wc-command-implementation, wc-l-command-implementation, wc-c-command-implementation): New variables. (%commands): Add wc command. --- guix/build/bournish.scm | 58 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-) diff --git a/guix/build/bournish.scm b/guix/build/bournish.scm index 1f17e0a..a8f6591 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 <[email protected]> +;;; Copyright © 2016 Efraim Flashner <[email protected]> ;;; ;;; This file is part of GNU Guix. ;;; @@ -25,6 +26,7 @@ #: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) #:export (%bournish-language)) @@ -103,6 +105,59 @@ characters." ((@ (guix build utils) dump-port) port (current-output-port)) *unspecified*))) +(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 (only-files files) + (filter (lambda (file) + (catch 'system-error + (lambda () + (stat file)) + (lambda args + (let ((errno (system-error-errno args))) + (format (current-error-port) "~a: ~a~%" + file (strerror errno)) + #f)))) + files)) + +(define (wc-command-implementation . files) + (for-each + (lambda (file) + (let-values (((lines chars) + (call-with-input-file file lines+chars))) + (format #t "~a ~a ~a~%" lines chars file))) + ((@@ (guix build bournish) only-files) files))) + +(define (wc-l-command-implementation . files) + (for-each + (lambda (file) + (let-values (((lines chars) + (call-with-input-file file lines+chars))) + (format #t "~a ~a~%" lines file))) + ((@@ (guix build bournish) only-files) files))) + +(define (wc-c-command-implementation . files) + (for-each + (lambda (file) + (let-values (((lines chars) + (call-with-input-file file lines+chars))) + (format #t "~a ~a~%" chars file))) + ((@@ (guix build bournish) only-files) files))) + +(define (wc-commands . args) + (cond ((member "-l" args) `((@@ (guix build bournish) wc-l-command-implementation) ,@(delete "-l" args))) + ((member "-c" args) `((@@ (guix build bournish) wc-c-command-implementation) ,@(delete "-c" args))) + (else `((@@ (guix build bournish) wc-command-implementation) ,@args)))) + (define (help-command . _) (display "\ Hello, this is Bournish, a minimal Bourne-like shell in Guile! @@ -129,7 +184,8 @@ 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-commands))) (define (read-bournish port env) "Read a Bournish expression from PORT, and return the corresponding Scheme -- 2.8.4
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