MiniPascal

MiniPascal as a Racket language

This is the minipascal package. It provides MiniPascal as a new #lang language.

After installation (see later) the following program will run as is in DrRacket.

#lang minipascal
program fact;
type 
  int=integer;
function fact(n:int):int;
  begin
    if n=0 then
      fact:=1
    else
      fact:=n*fact(n-1)
  end;
begin
  writeln(fact(10));
end.

See mini-pascal-grammar.rkt for a complete grammar.

Features

The following features are supported:

• constant definitions
• type definitions
• function and procedure declarations
• nested functions and procedures
• base types: integer, boolean, char,
• arrays
• strings
• integer and char can be used as index ranges

Compilers

MiniPascal comes with two compilers. The simple one in "semantics-simple.rkt" translates directly from Pascal to Racket without any (compile time) type checking. This compiler is written in the same spirit as the example in the Ragg tutorial. In other words it "compiles by macro expansion".

The other compiler in "semantics.rkt" demonstrates how scoping and type checking can by implemented. The compiler more traditional, it expands the whole Pascal program in one go.

To switch from the full compiler to the simple one, add simple to the #lang line. That is, the lines:

#lang minipascal
#lang minipascal simple

use the full and simple compiler respectively.

Exercises

• Add mod as an operator
• Add repeat
• Add case
• Add enumerated types
• Add real numbers
• Add records
• Add files

Installation

Install this package from the command line with:

raco pkg install --deps search-ask minipascal

or, by evaluating the following in DrRacket:

#lang racket

(require pkg)
(install "minipascal" #:deps 'search-ask)

Use the Racket package manager to install:

raco pkg install minipascal

References

Pascal ISO 7185 from 1990: http://pascal-central.com/docs/iso7185.pdf