@iftex
@finalout
@end iftex
-@comment $Id: scheme.texinfo,v 1.26 1993/10/16 05:31:51 jawilson Exp $
+@comment $Id: scheme.texinfo,v 1.27 1993/10/16 08:48:11 cph Exp $
@comment %**start of header (This is for running Texinfo on a region.)
@setfilename scheme
@settitle MIT Scheme Reference
@titlepage
@title{MIT Scheme Reference Manual}
-@subtitle Edition 1.25 alpha
+@subtitle Edition 1.27 alpha
@subtitle for Scheme Release 7.2
-@subtitle 14 October 1993
+@subtitle 16 October 1993
@author by Chris Hanson
@author the MIT Scheme Team
@author and a cast of thousands
* Numerical operations::
* Numerical input and output::
* Fixnum and Flonum Operations::
+* Random Numbers::
Fixnum and Flonum Operations
* Output Procedures::
* Format::
* Custom Output::
+* Prompting::
* Port Primitives::
Port Primitives
@example
@group
-
(list-transform-positive '(1 2 3 4 5) odd?) @result{} (1 3 5)
-
(list-transform-negative '(1 2 3 4 5) odd?) @result{} (2 4)
@end group
@end example
* Output Procedures::
* Format::
* Custom Output::
+* Prompting::
* Port Primitives::
@end menu
@comment **** end CLTL ****
-@node Custom Output, Port Primitives, Format, Input/Output
+@node Custom Output, Prompting, Format, Input/Output
@section Custom Output
MIT Scheme provides hooks for specifying that certain kinds of objects
depending on other components of @var{unparser-state}.
@end deffn
-@node Port Primitives, , Custom Output, Input/Output
+@node Prompting, Port Primitives, Custom Output, Input/Output
+@section Prompting
+@cindex prompting
+
+This section describes procedures that prompt the user for input. Why
+should the programmer use these procedures when it is possible to do
+prompting using ordinary input and output procedures? One reason is
+that the prompting procedures are more succinct. However, a second and
+better reason is that the prompting procedures can be separately
+customized for each user interface, providing more natural interaction.
+The interfaces for Edwin and for GNU Emacs have already been customized
+in this fashion; because Edwin and Emacs are very similar editors, their
+customizations provide very similar behavior.
+
+@findex nearest-cmdl/port
+Each of these procedure accepts an optional argument called @var{port},
+which must be an @sc{i/o} port if given. If not given, this port
+defaults to the value of @code{(nearest-cmdl/port)}, the @sc{i/o} port
+of the @sc{rep} loop; this is usually the console @sc{i/o} port.
+
+The required argument @var{prompt} must be a string.
+
+@deffn {procedure+} prompt-for-command-expression prompt [port]
+Prompts the user for an expression that is to be executed as a command.
+This is the procedure called by the @sc{rep} loop to read the user's
+expressions.
+
+The prompt string is formed by appending a space to @var{prompt}, unless
+@var{prompt} already ends in a space.
+
+The default behavior of this procedure is to print the prompt string
+preceded by two newlines, flush the output buffer, then read an object
+and return it.
+
+Under Edwin and Emacs, before the object is read, the interaction buffer
+is put into a mode that allows expressions to be edited and submitted
+for input using specific editor commands. The first expression that is
+submitted is returned as the value of this procedure.
+@end deffn
+
+@deffn {procedure+} prompt-for-command-char prompt [port]
+@findex char-graphic?
+Prompts the user for a single character that is to be executed as a
+command; the returned character is guaranteed to satisfy
+@code{char-graphic?}. If at all possible, the character is read from
+the user interface using a mode that reads the character as a single
+keystroke; in other words, it should not be necessary for the user to
+follow the character with a carriage return or similar rubbish.
+
+@findex debug
+@findex where
+This is the procedure called by @code{debug} and @code{where} to read
+the user's commands.
+
+The prompt string is formed by appending a space to @var{prompt}, unless
+@var{prompt} already ends in a space.
+
+The default behavior of this procedure is to print the prompt string
+preceded by two newlines, flush the output buffer, read a character in
+@dfn{raw} mode, echo that character, and return it.
+
+Under Edwin and Emacs, instead of reading a character, the interaction
+buffer is put into a mode in which graphic characters submit themselves
+as input. After this mode change, the first such character submitted is
+returned as the value of this procedure.
+@end deffn
+
+@deffn {procedure+} prompt-for-expression prompt [port]
+Prompts the user for an expression.
+
+The prompt string is formed by appending a colon and a space to
+@var{prompt}, unless @var{prompt} already ends in a space.
+
+The default behavior of this procedure is to print the prompt string
+preceded by two newlines, flush the output buffer, then read an object
+and return it.
+
+Under Edwin and Emacs, the expression is read in the minibuffer.
+@end deffn
+
+@deffn {procedure+} prompt-for-evaluated-expression prompt [environment [port]]
+Prompts the user for an evaluated expression. Calls
+@code{prompt-for-expression} to read an expression, then evaluates the
+expression using @var{environment}; if @var{environment} is not given,
+the @sc{rep} loop environment is used.
+@end deffn
+
+@deffn {procedure+} prompt-for-confirmation prompt [port]
+Prompts the user for confirmation. The result yielded by this procedure
+is a boolean.
+
+The prompt string is formed by appending the string @code{" (y or n)? "}
+to @var{prompt}, unless @var{prompt} already ends in a space.
+
+The default behavior of this procedure is to print the prompt string
+preceded by two newlines, flush the output buffer, then read a
+character. If the character is @code{#\y}, @code{#\Y}, or
+@code{#\space}, the procedure returns @code{#t}; If the character is
+@code{#\n}, @code{#\N}, or @code{#\rubout}, the procedure returns
+@code{#f}. Otherwise the prompt is repeated.
+
+Under Edwin or Emacs, the confirmation is read in the minibuffer.
+@end deffn
+
+@node Port Primitives, , Prompting, Input/Output
@section Port Primitives
@cindex port primitives
projects / mit-scheme.git / commitdiff