Running Miranda

The functional programming language Miranda has an implementation running on one of the CS Linux workstations (miranda.cs.uiowa.edu). This machine is not accessible from off-campus, so you need to ssh to linux.cs.uiowa.edu, and from there ssh miranda.

Programs are composed in a text file using the editor of your choice. The command to invoke the Miranda system is: 'mira filename'. The filename in the command (if any) designates a text file containing a Miranda program (or script as it’s called in Miranda). Note that files containing Miranda scripts must have a name which ends with '.m'. Also, if the 'mira' command is issued from another of the CS Linux workstations, a session on the miranda machine is automatically initiated.

Assuming that a script compiles successfully, the remainder of the session is a series of interactions with the Miranda system. At each Miranda prompt you enter an arbitrary Miranda expression whose constituent functions are defined in the script (or are pre-defined), the result will be displayed, and the prompt for the next input issued.

An entry with first character '/' is regarded as a command rather than an expression to be evaluated. The following commands (plus others) are available:

/quit - end Miranda session

/help - display info on the Miranda commands

/man - enter on-line Miranda documentation subsystem

/edit - edit current script (vi is default editor, can be reset to your choice)

/aux - print list of auxiliary commands

Another command allows you to name your default editor, and then you can switch between editing and executing your program without stopping and restarting Miranda. There are various other types of input permitted at the Miranda prompt and they are explained by the help command.

Miranda has excellent, comprehensive documentation available on-line (use the /man command after starting Miranda), and /man entry 100 is a good place to start and is required reading. The functions which are pre-defined are fully described in the on-line manual (/man entry 28). The precise BNF syntax and related constraints are given in /man entries 24, 25 & 26.

Note that to access the manual entries in Miranda you must set the following environment variables:

tcsh

• setenv VIEWER "less -e"
• setenv MENUVIEWER cat
• setenv RETURNTOMENU YES

bash

• export VIEWER="less -e"
• export MENUVIEWER=cat
• export RETURNTOMENU=YES

The directory /usr/lib/miralib/ex (on the Miranda machine) contains a collection of example Miran-a scripts — they are briefly described in the README file also in this directory. Examples that we’ll discuss in class will be placed in our class directory and will be closely oriented towards our uses of Miranda.