mpri-funcprog-project/src/RawLambda.ml
Théophile Bastian 7bc7921fc3 Add IfZero in the syntax + placeholders
Also add (* TODO ifzero *) all around as placeholders
2018-02-16 00:19:44 +01:00

56 lines
1.6 KiB
OCaml

(* Variables are strings. *)
type variable =
string
(* Every [let] binding is marked recursive or nonrecursive. *)
and recursive =
| Recursive
| NonRecursive
(* The four standard integer arithmetic operations are supported. *)
and binop =
| OpAdd
| OpSub
| OpMul
| OpDiv
(* This language is the untyped lambda-calculus, extended with possibly
recursive [let] bindings, integer literals (that is, constants), integer
arithmetic operations, and the primitive operation [print], which prints an
integer value and returns it. *)
and term_ =
| Var of variable
| Lam of variable * term
| App of term * term
| Lit of int
| BinOp of term * binop * term
| Print of term
| Let of recursive * variable * term * term
| IfZero of term * term * term
(* Every abstract syntax tree node of type [term] is annotated with a place,
that is, a position in the source code. This allows us to produce a good
error message when a problem is detected. *)
and term =
term_ placed
(* A value of type ['a placed] can be thought of as a value of type ['a]
decorated with a place. *)
and 'a placed = {
place: Error.place;
value: 'a
}
(* The following annotation requests the automatic generation of a [show_]
function for each of the types defined above. For instance, the function
[show_term], of type [term -> string], converts a term to a string. These
functions can be useful during debugging. Running with [--debug] causes
every intermediate abstract syntax tree to be displayed in this way. *)
[@@deriving show { with_path = false }]