https://github.com/gabryon99/imp
IMP is a small imperative programming language.
https://github.com/gabryon99/imp
imperative menhir ocaml ocamllex programming-language semantics
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IMP is a small imperative programming language.
- Host: GitHub
- URL: https://github.com/gabryon99/imp
- Owner: gabryon99
- Created: 2022-04-29T21:51:03.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2022-05-01T15:44:57.000Z (over 3 years ago)
- Last Synced: 2024-12-28T14:36:56.263Z (10 months ago)
- Topics: imperative, menhir, ocaml, ocamllex, programming-language, semantics
- Language: OCaml
- Homepage:
- Size: 8.79 KB
- Stars: 2
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
## IMP - a simple imperative language
> **IMP** is a small language of while programs. IMP is called an "imperative" language because program execution involeves carrying out a series of explicit commands to change state.
>
> *The formal semantics of programming languages* - *Glynn Winskel*
This OCaml project implements a simple interpreter of the IMP programming language described by Winskell. The language is extended with some tweaks which are not present in the book, such as the `print` and `read` functions. The interpreter makes use of `ocamllex`, `menhir` and `ppx` as dependencies. To build the executable run `dune run` and to execute type `dune exec imp`.
Be aware that this implementation is a toy, it surely has some not checked errors 🙂
### Grammar
The grammar is expressed using the BNF.
```
Arithmetic Expressions
a ::= n | X | a0 + a1 | a0 - a1 | a0 * a1 | read | ( a )
Boolean Expressions
b ::= true | false | a0 = a1 | a0 <= a1 | a0 < a1 | a0 >= a1 | a0 > a1 | !b | b0 || b1 | b0 && b1 | ( b )
Commands
c ::= skip | print a | c0; c1 | if b then c0 else c1 end | while b do c end
```
### A simple program
The program shown below implement the factorial function.
```
n := read;
f := 1;
while n > 0 do
f := f * n;
n := n - 1;
end
print f;
```
All the examples can be found inside the `playground` directory.
### Added Features
The features added to the language are a few:
* the `end` keyword has been introduced to mark the end of while/if block;
* the `read` expression is useful to read a number from the *standard input* (⚠️ No check is performed onto the typed input);
* the `print` command is the most complex one: it prints a number onto the screen.