This project is a compiler (and an interpreter) Mallard, a simple programming language.
Out of a sense of environmental responsibility, this compiler is constructed largely from post-consumer waste code, primarily from the Calculator project. However, many parts had to be melted down and recast, and almost every part required at least some small modification.
Mallard has control structures like if/then/else/fi and while/do/od, which our calculator did not have.
- while loops are written like this:
while x do
fact = fact * x ;
x = x - 1 ;
od
The condition can be any expression. 0 is interpreted as False, and any non-zero value is True. The block between do and od is executed as long as the condition (x in the example) evaluates to a non-zero value.
- if/then/else/fi, with an optional else part. The condition after the
ifis like the condition in thewhileloop, just an expression that evaluates to 0 for False or anything else for True. In practice that means it is very hard to test for anything but equality. Here's a program that does use an if/then/else to test for equality:
Mallard also has a read expression
for reading from the keyboard and a
print statement for printing.
An interpreter is provided. You are building a code generator for a compiler that generates code for a Duck Machine 2019W.
See docs/HOWTO-compile.md