doc: cookbook: Mention "#true" and "#false".

* doc/guix-cookbook.texi (A Scheme Crash Course): Mention "#true" and
"#false".
(Extended example): Likewise.
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Ludovic Courtès 2020-10-14 11:28:30 +02:00
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@ -128,8 +128,9 @@ REPL.
@item
Scheme syntax boils down to a tree of expressions (or @emph{s-expression} in
Lisp lingo). An expression can be a literal such as numbers and strings, or a
compound which is a parenthesized list of compounds and literals. @code{#t}
and @code{#f} stand for the Booleans ``true'' and ``false'', respectively.
compound which is a parenthesized list of compounds and literals. @code{#true}
and @code{#false} (abbreviated @code{#t} and @code{#f}) stand for the
Booleans ``true'' and ``false'', respectively.
Examples of valid expressions:
@ -1090,9 +1091,9 @@ this:
#t)
@end lisp
The procedure must return @code{#t} on success. It's brittle to rely on the return
The procedure must return @code{#true} on success. It's brittle to rely on the return
value of the last expression used to tweak the phase because there is no
guarantee it would be a @code{#t}. Hence the trailing @code{#t} to ensure the right value
guarantee it would be a @code{#true}. Hence the trailing @code{#true} to ensure the right value
is returned on success.
@subsubsection Code staging