hacalc

This is an example interpreter for PatternT library
The library expects from interpreters to add builtin definitions and other stuff that cannot be expressed with patterns
Here is what hacalc adds to PatternT:

• operations on numbers: $mult, $add, $div, ..
• deep equality checker - $equal (it simplifies arguments before actual stupid check)
• $num? $le? $lt?
• staged rule application. Example:

* -> +
------
+ -> *

Above will not create an infinite loop because rules separated by ----- are applied in separate groups, in order

Examples

Using 'Calculator simple' rules from here: https://github.com/Donaim/PatternT-tests/blob/master/examples/test1

3 * x + (1 * x + 5 * x)
>>> 9 * x

3 * x + (1 * x + 1 + 5 * x)
>>> 1 + (9 * x)

3 * x + 3 + 5 * x + 10 + (1 * x + 1 + 5 * x)
>>> 14 + (14 * x)

Using 'Lambda calculus' rules from here: https://github.com/Donaim/PatternT-tests/blob/master/examples/test1

+ (succ (succ 0)) (succ 0)
>>> (succ (succ (succ 0)))

show (+ (succ (succ 0)) (succ 0))
>>> 3

show (fac (succ (succ (succ (succ 0
>>> 24

> inf (succ (succ 0))
>>> true

> (succ (succ 0)) inf
>>> false

HOWTO

This program can be used as a standalone compiler, but there is also a hacalc-ide that is much nicer to use

Instructions for standalone compiler:

1. Write rules to rules/file
2. $ stack run -- rules/file
3. Input expressions