Dysfunctionally Functional Language

This is a compiler frontend ie an interpreter written in OCAML language.

Installation guidelines

You will need to install:

• opam: the package manage for OCaml. Follow instructions here: https://opam.ocaml.org/doc/Install.html
• ocaml: the language we use as host for implementing our interpreters. Follow the instructions here: https://ocaml.org/docs/install.html
• menhir: the lexer and parser generator. Just type opam install menhir
• ounit: the unit testting library. Just type opam install ounit2
• dune: the standard build system for OCaml. Just type opam install dune
• Steps to execute

1. clone the repo
2. move into folder cd Dysfunctionally_Functional
3. open command-line and execute interp <your expressions in quote>

Steps for adding different features

for language extension:

Syntax

• Concrete Syntax: rules you have to follow to filter out incorrect code
• Abstract Syntax:

Semantics → is how we run code

• Specification
  • Results
  • Evaluation Judgements
  • Evaluation rules
• Implementation

using parse in utop you can convert from conceret to abstract syntax

ARITH

Grammar Notation

<Expression>::= <Number>
<Expression>::= <Expression> − <Expression>
<Expression>::= <Expression>/<Expression>
<Expression>::= (<Expression>)

Error Monad

The infix operator (>>=) is called bind and is left associative. Consider the expression c >>= f; its behavior may be described as follows:

1. evaluate the argument c to produce a result (i.e. a non-error value or an error value); if c returns an error, propagate it and conclude.
2. otherwise, if c returns Ok v, for some expressed value v, then pass v on to f by evaluating f v.

Let

<Expression>::= <Number>
<Expression>::= <Identifier>
<Expression>::= <Expression><BOp><Expression>
<Expression>::= zero?(<Expression>)
<Expression>::= if<Expression> then <Expression> else <Expression>
<Expression>::= let <Identifer> = <Expression> in <Expression>
<Expression>::= (<Expression>)

<BOp>::= + | - | * | /

Proc

〈Expression〉 ::= 〈Number〉
〈Expression〉 ::= 〈Identifier〉
〈Expression〉 ::= 〈Expression〉〈BOp〉〈Expression〉
〈Expression〉 ::= zero?(〈Expression〉)
〈Expression〉 ::= if 〈Expression〉then 〈Expression〉else 〈Expression〉
〈Expression〉 ::= let 〈Identifier〉= 〈Expression〉in 〈Expression〉
〈Expression〉 ::= (〈Expression〉)
〈Expression〉 ::= proc(〈Identifier〉){〈Expression〉}
〈Expression〉 ::= (〈Expression〉〈Expression〉)
〈BOp〉 ::= + |- |* |/

Rec

〈Expression〉 ::= 〈Number〉
〈Expression〉 ::= 〈Identifier〉
〈Expression〉 ::= 〈Expression〉〈BOp〉〈Expression〉
〈Expression〉 ::= zero?(〈Expression〉)
〈Expression〉 ::= if 〈Expression〉then 〈Expression〉else 〈Expression〉
〈Expression〉 ::= let 〈Identifier〉= 〈Expression〉in 〈Expression〉
〈Expression〉 ::= (〈Expression〉)
〈Expression〉 ::= proc(〈Identifier〉){〈Expression〉}
〈Expression〉 ::= (〈Expression〉〈Expression〉)
〈Expression〉 ::= letrec 〈Identifier〉(〈Identifier〉) = 〈Expression〉in 〈Expression〉
〈BOp〉 ::= + |- |* |