mira.1

.TH MIRA 1 "November 2019"
.SH NAME
mira \- the Miranda(tm) functional programming system
.SH SYNOPSIS
.B mira
[options]
[file]
.fi
.SH DESCRIPTION
Miranda is a functional programming system with lazy evaluation,
polymorphic strong typing and function definition by pattern matching.
.PP
The \fBmira\fP program takes a single argument which is the name of
a file of definitions (called a "script").  If no argument is given a
default name "\fBscript.m\fP" is assumed.  The names of files
containing miranda scripts must end in ".m" and \fBmira\fP will
add this if missing. The specified file need not yet exist - in  this
case  you  will  be  starting  a  Miranda  session with an empty current
script.
.PP
The basic action of the Miranda system is to evaluate expressions in
the environment established by the script, so in its simplest mode of
use it behaves like a desk calculator.  Expressions are typed one per
line, terminated by ENTER.
."For example
.".nf
."      Miranda \fBproduct [1..40]
."      815915283247897734345611269596115894272000000000\fP
.".fi
."There is a `standard environment' of predefined functions, such as
."product, which are always in scope.
The interpreter also accepts
certain commands (mostly beginning with a `\fB/\fP' character) - these
include \fB/help\fP or \fB/h\fP which prints a summary of the available
commands, and \fB/man\fP or \fB/m\fP which gives access to the online
manual of the Miranda system (menu driven and self explanatory). This
documents all aspects of the Miranda language and system and should be
consulted for further details.  It is also possible to access the
Miranda system manual directly from a UNIX shell by the command \fBmira
-man\fP.
.SH OPTIONS
.TP
.B -lib pathname
Specifies location of the miralib directory.  For default see \fBFILES\fP.
Can also be done by setting environment variable \fBMIRALIB\fP.  The location
of the miralib directory can be interrogated (but not changed) from
within the miranda session by the command `/miralib'.
.TP
.B -gc
Switches on a flag causing the garbage collector  to  print  information
each  time  a  garbage  collection  takes  place.  This flag can also be
switched on and off from within the  miranda  session  by  the  commands
`/gc', `/nogc'.
.TP
.B -count
Switches  on  a  flag  causing  statistics  to  be  printed  after  each
expression  evaluation.   This flag can also be switched on and off from
within the miranda session by the commands `/count', `/nocount'.
.TP
.B -list (-nolist)
Switches on (off) a flag causing Miranda scripts to  be  listed  to  the
screen  during  compilation.   This flag can also be switched on and off
from within the miranda session by the commands `/list', `/nolist'.
.TP
.B -nostrictif
Enables the compiler to accept old Miranda scripts with no `\fBif\fP'
after the guard comma.
.TP
.B -hush (-nohush)
The  miranda  system  decides  whether  or not to give prompts and other
feedback by testing its standard input with `isatty'.  If  the  standard
input  does not appear to be a terminal it assumes that prompts would be
inappropriate, otherwise it gives them.  In either case  this  behaviour
can be overriden by an explicit flag ("-hush" for silence, "-nohush" for
prompts etc).  This switch is  also  available  from  within  a  miranda
session by the commands `/hush', `/nohush'.
.TP
.B -dic SIZE
Causes  the  dictionary, used by the compiler to store identifiers etc.,
to be SIZE bytes (default 100k).  This can be interrogated (but not changed)
from within the miranda session by the command `/dic'.
.TP
.B -heap SIZE
Causes the heap to be SIZE cells (default 2500k).  This can
changed within the miranda session by the command `/heap SIZE'.
A cell is 9 bytes (2 words of 32 bits, and a tag field).
.TP
.B -editor prog
Causes the resident editor (usual default `\fBvi\fP') to be \fBprog\fP
instead.  This can also be done from within the miranda session by the
command \fB/editor prog\fP.  Any occurrences of \fB!\fP and \fB%\fP in
\fBprog\fP will be replaced by the line number and the name of the file
to be edited, respectively.  For more detailed discussion see online manual
subsection 31/5.
.TP
.B -UTF-8 (-noUTF-8)
Assume the current locale is (is not) UTF-8 overriding environment vars
(version 2.044 and later).
.TP
.B -stdenv
Run mira without loading the standard environment.  Any script needing
functions from <stdenv> will then have to explicitly %include <stdenv>,
or define the required functions itself.  Not recommended as normal
practise and may have unexpected consequences.
.TP
.B -object
Used for debugging the compiler.  Modifies the  behaviour of ?identifier(s)
to show the associated combinator code, which may or may not be comprehensible
as there is no documentation other than the source code.
.SH SPECIAL CALLS
The following special calls to \fBmira\fP do not start a Miranda session
but accomplish another purpose.
.TP
.B mira -man
Enter Miranda online manual from the UNIX shell.  From within a
Miranda session this is done by the command `/man' or `/m'.
.TP
.B mira -version
Prints  version information.  This information can be obtained 
within a Miranda session by the command `/version' or `/v'.
.TP
.B mira -V
More detailed version information.  Can be obtained within a Miranda session
by the command `/V'.
.PP
The remaining special calls are discussed in more detail in the online manual
- we list them here for completeness.
.TP
.B mira -exec
Special call permitting the use of miranda script as a stand-alone
program. See online manual subsection 31/4 for details.
.TP
.B mira -exec2
As \fB-exec\fP except that it redirects stderr to a log file.
See online manual subsection 31/4 for details.
.PP
These three relate to separate compilation and Miranda's
built in `make' facility.  See online manual section 27 (\fBthe library
mechanism\fP):-
.TP
.B mira -make [files]
Checks that all the miranda source files listed have up-to-date .x
(intermediate code) files, triggering compilation processes if necessary.
.TP
.B mira -exports [files]
Sends to stdout a list of the identifiers exported from the given
miranda source files, together with their types (may force compilation
if needed).
.TP
.B mira -sources [files]
Send to stdout a list of all the Miranda source files on which the given
source files directly or indirectly depend (via \fB%include\fP or \fB%insert\fP
statements), excluding the standard environment \fB<stdenv>\fP.
.TP
.B mira -version
Gives version information.  This information can also be  obtained  from
within a Miranda session by the command `/version'.
.TP
.B mira -V
More detailed version information.
.SH ENVIRONMENT
.TP
.B MIRALIB
Specifies the location of the miralib directory.  A \fB-lib\fP flag,
if present, overrides this.  For default location see \fBFILES\fP.
.TP
.B EDITOR
The  first time it is called (i.e. if no .mirarc file is present
in the home directory or in miralib) the miranda  system  takes
the  preferred editor from this environment variable - if
not set `\fBvi\fP' is assumed.  Chosen editor can be changed from
within a Miranda session by the command \fB/editor prog\fP.
Any occurrences of \fB!\fP and \fB%\fP in \fBprog\fP will be replaced
by the line number and the name of the file to be edited, respectively.
For more detailed discussion see online manual subsection 31/5.
.TP
.B LC_CTYPE, LANG
At startup (version 2.044 and later) the miranda system inspects \fBLC_TYPE\fP,
or if that is empty \fBLANG\fP,  to
determine  if  it  is running in a UTF-8 locale.  On Windows/Cygwin this
information is taken from the \fBuser-default ANSI code page\fP.  An
explicit \fB-UTF-8\fP or \fB-noUTF-8\fP flag, if present, overrides.
.TP
.B RECHECKMIRA
If this is set to any non-empty string the Miranda system checks to see
if any relevant source file has been updated, and performs any
necessary recompilation, before each interaction with the user.  This is
the appropriate behaviour if an editor window is being kept open during
the Miranda session.  By default the check is performed only after `\fB/e\fP'
commands and `\fB!\fP' escapes.  This can also be controlled from
within a Miranda session by the commands `/recheck', `/norecheck'.
.TP
.B SHELL
Determines what shell is  used  in  `!'  escapes. This  will  normally
contain  the  name of the user's login shell.  If no \fBSHELL\fP is present in
the environment, \fB/bin/sh\fP is assumed.
.TP
.B MIRAPROMPT
Sets a string to be used as session prompt instead of the default prompt
"Miranda " (version 2.044 and later).
.TP
.B NOSTRICTIF
If this is set to any non-empty string Miranda accepts old scripts with no `\fBif\fP'
after the guard comma.  Equivalent to calling mira with option
\fB-nostrictif\fP.  Deprecated - you should put the `\fBif\fP's in.
.PP
The behaviour of the menudriver program that displays pages of the online
manual can be modified using three environment variables:-
.TP
.B VIEWER
The program used for displaying pages of the online manual.
If  this  variable is not set the default is
normally `\fBmore -d\fP' or (roughly equivalent) `\fBless -EX\fP'.
If you set \fBVIEWER\fP to something, you may also need to set an  environment
variable \fBRETURNTOMENU\fP.
.TP
.B RETURNTOMENU=YES 
Prevents another prompt being given after displaying each section,
causing instead an immediate return to contents page.  Appropriate if
\fBVIEWER\fP is a program that pauses for input at end of file (e.g.
`\fBless\fP').  It should be `\fBNO\fP' if \fBVIEWER\fP is a program that
quits silently at end of file (e.g. `\fBmore -d\fP', `\fBless -EX\fP').
.TP
.B MENUVIEWER
Can be used  to
specify  the  program  used to display manual contents pages (default is
usually `\fBcat\fP' or `\fBmore\fP').
.PP
To find the current settings of the online manual enter \fB???\fP
to the "next selection" prompt of the manual system.
.SH FILES
.TP
.B /usr/lib/miralib
A directory containing files which \fBmira\fP needs - by default it
looks for this at \fB/usr/lib/miralib\fP, then \fB/usr/local/lib/miralib\fP,
and lastly at \fB./miralib\fP.  If it does not find a miralib of the
same version number as itself in one of these places it exits with a panic
message.  This behaviour can be overriden with the \fB-lib\fP option or
by setting the environment variable \fBMIRALIB\fP.
.TP
.B $HOME/.mirarc
Records most recent settings of heap size, dictionary size, editor
and various flags which can be toggled during a session.  Written and
read by \fBmira\fP using a peculiar format, not intended to be edited by
humans.  The settings can be interrogated within a Miranda session
by the command \fB/settings\fP or \fB/s\fP, and changed by various session
commands (use \fB/aux\fP or \fB/a\fP to list these).  The only setting
which cannot be changed in a session is dictionary
size - this is done using the \fB-dic\fP option when mira is invoked.
This rarely needs to be changed, however.
.PP
If a \fB.mirarc\fP is
copied to \fBmiralib/.mirarc\fP the settings it records will be picked
up by new users, who will not yet have their own \fB.mirarc\fP file.  This
allows an administrator to change the default settings, e.g. to
have a default editor other than \fBvi\fP.  The \fB$HOME/.mirarc\fP
once created will override the global one, however, allowing users
to make individual choices.
.SH SEE ALSO
.PP
.B http://miranda.org.uk
the Miranda home page.
.PP
D.A.Turner \fBAn Overview of Miranda\fP, SIGPLAN Notices, 21(12), December 1986.
A convenient summary of the main features of Miranda.
.PP
\fBMiranda System Manual\fP.  Accessed
by \fBmira -man\fP or \fB/man\fP from within a Miranda session.
.SH COPYRIGHT
The Miranda system  is  Copyright  (c)  Research  Software
Limited 1985-2019. For distribution terms see the file "COPYING" included
in the distribution.