Scripts

In Miranda the script is  the  persistent  entity  that  is  saved  from
session  to session (i.e.  it plays the role of what is called a program
in conventional languages).  Associated with a Miranda  session  at  any
given  time  is  a  single current script, identified by a UNIX pathname
ending in `.m'.

A script is a collection of declarations, establishing an environment in
which  you  wish to evaluate expressions.  The order of the declarations
in a script is not significant - for example  there  is  no  requirement
that an identifier be defined before it is used.

An identifier may not have more than one top-level binding  in  a  given
script.

Here are the kinds of declaration that can occur in a script:

1)  a  definition (of a function, data structure etc. - see manual entry
`definitions' for more details).  Example
	fac n = product[1..n]

2) a specification of the type of one or more identifiers, of the form
	var-list :: <type>
Example
	fac :: num->num
See 'Basic type structure' for an account of possible types.  Note  that
these  type  specifications are normally optional, since the compiler is
able  to  deduce  them  from  the  definitions  of   the   corresponding
identifiers.  It is however possible to introduce an identifier by means
of a type specification only, without  giving  it  a  defining  equation
(such  identifiers  are  said  to be `specified but not defined' and are
useful  in  program  development).   A  special  case  of  this  is  the
introduction  of  an  otherwise undefined typename - see separate manual
entry on `placeholder types'.

3) the definition of a user defined type - these  are  of  three  kinds,
synonyms, algebraic types, and abstract types (see separate manual entry
on each).

4) a library directive (%export,  %include  or  %free)  these  are  used
specify  the  interfaces  between  separately  compiled  scripts  -  see
separate manual entry on the library mechanism.

There is a manual entry giving the formal syntax of Miranda scripts.

Note
 A directory called `ex' (meaning `examples') containing a collection of
example  scripts  is supplied with the Miranda system, and will be found
under the `miralib' directory (usually kept at  /usr/lib/miralib  -  the
Miranda  session  command  `/miralib'  will tell you where it is on your
system).

A convention  which  the  Miranda  system  consistently  understands  in
Miranda  session  commands,  library  directives etc. is that a pathname
enclosed in <angle_brackets>, instead of "string_quotes" is relative  to
the  miralib  directory.   In  particular  note that the Miranda session
command
	/cd <ex>
will change your current directory to  be  "..../miralib/ex".   You  can
then say, e.g.
	!ls
to see what's in there.  In fact there is a README file, so a good thing
to say next would be
	!vi README

