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authorLudovic Courtès <ludo@gnu.org>2019-11-25 21:55:46 +0100
committerLudovic Courtès <ludo@gnu.org>2019-11-26 00:16:35 +0100
commitcf1e6f5f9016b3471f10581ee840c26398f44736 (patch)
tree17f80e99e2835677f5f6c6015cf6b6320254cc01
parent0cbef07b34bbe00f9728ad39308ca209c9e8f428 (diff)
downloadguix-cf1e6f5f9016b3471f10581ee840c26398f44736.tar
guix-cf1e6f5f9016b3471f10581ee840c26398f44736.tar.gz
doc: cookbook: Use @result{} & co. instead of a '>' prompt.
* doc/guix-cookbook.texi (A Scheme Crash Course) (Extended example): Use @result{}, @print{}, and @error{}.
-rw-r--r--doc/guix-cookbook.texi89
1 files changed, 48 insertions, 41 deletions
diff --git a/doc/guix-cookbook.texi b/doc/guix-cookbook.texi
index c8d9beaa66..0a33efc73a 100644
--- a/doc/guix-cookbook.texi
+++ b/doc/guix-cookbook.texi
@@ -111,9 +111,10 @@ REPL} by running @code{guile} from the command line.
Alternatively you can also run @code{guix environment --ad-hoc guile -- guile}
if you'd rather not have Guile installed in your user profile.
-In the following examples we use the @code{>} symbol to denote the REPL
-prompt, that is, the line reserved for user input. @xref{Using Guile
-Interactively,,, guile, GNU Guile Reference Manual}) for more details on the
+In the following examples, lines show what you would type at the REPL;
+lines starting with ``@result{}'' show evaluation results, while lines
+starting with ``@print{}'' show things that get printed. @xref{Using Guile
+Interactively,,, guile, GNU Guile Reference Manual}), for more details on the
REPL.
@itemize
@@ -126,12 +127,15 @@ and @code{#f} stand for the Booleans ``true'' and ``false'', respectively.
Examples of valid expressions:
@lisp
-> "Hello World!"
"Hello World!"
-> 17
+@result{} "Hello World!"
+
17
-> (display (string-append "Hello " "Guix" "\n"))
-"Hello Guix!"
+@result{} 17
+
+(display (string-append "Hello " "Guix" "\n"))
+@print{} Hello Guix!
+@result{} #<unspecified>
@end lisp
@item
@@ -144,8 +148,8 @@ last evaluated expression as its return value.
Anonymous functions are declared with the @code{lambda} term:
@lisp
-> (lambda (x) (* x x))
-#<procedure 120e348 at <unknown port>:24:0 (x)>
+(lambda (x) (* x x))
+@result{} #<procedure 120e348 at <unknown port>:24:0 (x)>
@end lisp
The above procedure returns the square of its argument. Since everything is
@@ -153,18 +157,18 @@ an expression, the @code{lambda} expression returns an anonymous procedure,
which can in turn be applied to an argument:
@lisp
-> ((lambda (x) (* x x)) 3)
-9
+((lambda (x) (* x x)) 3)
+@result{} 9
@end lisp
@item
Anything can be assigned a global name with @code{define}:
@lisp
-> (define a 3)
-> (define square (lambda (x) (* x x)))
-> (square a)
-9
+(define a 3)
+(define square (lambda (x) (* x x)))
+(square a)
+@result{} 9
@end lisp
@item
@@ -178,8 +182,8 @@ Procedures can be defined more concisely with the following syntax:
A list structure can be created with the @code{list} procedure:
@lisp
-> (list 2 a 5 7)
-(2 3 5 7)
+(list 2 a 5 7)
+@result{} (2 3 5 7)
@end lisp
@item
@@ -188,20 +192,21 @@ term is not called over the other terms. Thus it effectively returns a list
of terms.
@lisp
-> '(display (string-append "Hello " "Guix" "\n"))
-(display (string-append "Hello " "Guix" "\n"))
-> '(2 a 5 7)
-(2 a 5 7)
+'(display (string-append "Hello " "Guix" "\n"))
+@result{} (display (string-append "Hello " "Guix" "\n"))
+
+'(2 a 5 7)
+@result{} (2 a 5 7)
@end lisp
@item
-The @emph{quasiquote} disables evaluation of a parenthesized expression until
+The @dfn{quasiquote} disables evaluation of a parenthesized expression until
a comma re-enables it. Thus it provides us with fine-grained control over
what is evaluated and what is not.
@lisp
-> `(2 a 5 7 (2 ,a 5 ,(+ a 4)))
-(2 a 5 7 (2 3 5 7))
+`(2 a 5 7 (2 ,a 5 ,(+ a 4)))
+@result{} (2 a 5 7 (2 3 5 7))
@end lisp
Note that the above result is a list of mixed elements: numbers, symbols (here
@@ -211,25 +216,27 @@ Note that the above result is a list of mixed elements: numbers, symbols (here
Multiple variables can be named locally with @code{let}:
@lisp
-> (define x 10)
-> (let ((x 2)
- (y 3))
- (list x y))
-(2 3)
-> x
-10
-> y
-ERROR: In procedure module-lookup: Unbound variable: y
+(define x 10)
+(let ((x 2)
+ (y 3))
+ (list x y))
+@result{} (2 3)
+
+x
+@result{} 10
+
+y
+@error{} In procedure module-lookup: Unbound variable: y
@end lisp
Use @code{let*} to allow later variable declarations to refer to earlier
definitions.
@lisp
-> (let* ((x 2)
- (y (* x 3)))
- (list x y))
-(2 6)
+(let* ((x 2)
+ (y (* x 3)))
+ (list x y))
+@result{} (2 6)
@end lisp
@item
@@ -982,10 +989,10 @@ definition in @samp{$GUIX_CHECKOUT/guix/build/gnu-build-system.scm}:
Or from the REPL:
@lisp
-> (add-to-load-path "/path/to/guix/checkout")
-> ,module (guix build gnu-build-system)
-> (map first %standard-phases)
-(set-SOURCE-DATE-EPOCH set-paths install-locale unpack bootstrap patch-usr-bin-file patch-source-shebangs configure patch-generated-file-shebangs build check install patch-shebangs strip validate-runpath validate-documentation-location delete-info-dir-file patch-dot-desktop-files install-license-files reset-gzip-timestamps compress-documentation)
+(add-to-load-path "/path/to/guix/checkout")
+,use (guix build gnu-build-system)
+(map first %standard-phases)
+@result{} (set-SOURCE-DATE-EPOCH set-paths install-locale unpack bootstrap patch-usr-bin-file patch-source-shebangs configure patch-generated-file-shebangs build check install patch-shebangs strip validate-runpath validate-documentation-location delete-info-dir-file patch-dot-desktop-files install-license-files reset-gzip-timestamps compress-documentation)
@end lisp
If you want to know more about what happens during those phases, consult the