A simple recursive descent parser. Written for the formal languages course in HSE. The language is described with the following grammar:
S -> Commands | \epsilon
Commands -> Expr (; Commands)?
Expr > Ident = Expr
| Arithmetic
| ListExpr
ListExpr -> Ident = ListExpr
| Ident (++ ListExpr)?
| List (++ ListExpr)?
Arithmetic -> Ident = Arithmetic
| Term ((+ | -) Arithmetic)?
Term -> Power ((* | /) Term)?
Power -> Factor (^ Power)?
Factor -> Ident
| Num
| '(' Arithmetic ')'
| -Factor
List = '[' (NodeSequence | epsilon) ']'
NodeSequence = (Arithmetic | List) (, List)?
Ident -> [a-z]+
Num -> [0-9]+
Running the build script build.sh generates an executable Main. Main parses several inputs specified and terminates.
To run parser on your input, load Main into the interpreter ghci and execute parse <input> or modify Main.hs.
This should work on any version of the haskell compiler, but has only been tested on ghc 8.4.2.