diff options
Diffstat (limited to '')
| -rw-r--r-- | compiler/Extract.ml | 61 |
1 files changed, 55 insertions, 6 deletions
diff --git a/compiler/Extract.ml b/compiler/Extract.ml index 6c523549..dbca4f8f 100644 --- a/compiler/Extract.ml +++ b/compiler/Extract.ml @@ -577,12 +577,17 @@ and extract_field_projector (ctx : extraction_ctx) (fmt : F.formatter) in (* Check if we extract the type as a tuple, and it only has one field. In this case, there is no projection. *) - let has_one_field = + let num_fields = match proj.adt_id with | TAdtId id -> ( let d = TypeDeclId.Map.find id ctx.trans_types in - match d.kind with Struct [ _ ] -> true | _ -> false) - | _ -> false + match d.kind with + | Struct fields -> Some (List.length fields) + | _ -> None) + | _ -> None + in + let has_one_field = + match num_fields with Some len -> len = 1 | None -> false in if is_tuple_struct && has_one_field then extract_texpression ctx fmt inside arg @@ -590,7 +595,52 @@ and extract_field_projector (ctx : extraction_ctx) (fmt : F.formatter) (* Exactly one argument: pretty-print *) let field_name = (* Check if we need to extract the type as a tuple *) - if is_tuple_struct then FieldId.to_string proj.field_id + if is_tuple_struct then + match !backend with + | FStar | HOL4 | Coq -> FieldId.to_string proj.field_id + | Lean -> + (* Tuples in Lean are syntax sugar for nested products/pairs, + so we need to map the field id accordingly. + + We give two possibilities: + - either we use the custom syntax [.#i], like in: [(0, 1).#1] + - or we introduce nested projections which use the field + projectors [.1] and [.2], like in: [(0, 1).2.1] + + This necessary in some situations, for instance if we have + in Rust: + {[ + struct Tuple(u32, (u32, u32)); + ]} + + The issue comes from the fact that in Lean [A * B * C] and [A * (B * + C)] are the same type. As a result, in Rust, field 1 of [Tuple] is + the pair (an element of type [(u32, u32)]), however in Lean it would + be the first element of the pair (an element of type [u32]). If such + situations happen, we allow to force using the nested projectors by + providing the proper command line argument. TODO: we can actually + check the type to determine exactly when we need to use nested + projectors and when we don't. + + When using nested projectors, a field id i maps to: + - (.2)^i if i is the last element of the tuple + - (.2)^i.1 otherwise + where (.2)^i denotes .2 repeated i times. + For example, 3 maps to .2.2.2 if the tuple has 4 fields and + to .2.2.2.1 if it has more than 4 fields. + Note that the first "." is added below. + *) + let field_id = FieldId.to_int proj.field_id in + if !Config.use_nested_tuple_projectors then + (* Nested projection: "2.2.2..." *) + if field_id = 0 then "1" + else + let twos_prefix = + String.concat "." (Collections.List.repeat field_id "2") + in + if field_id + 1 = Option.get num_fields then twos_prefix + else twos_prefix ^ ".1" + else "#" ^ string_of_int field_id else ctx_get_field proj.adt_id proj.field_id ctx in (* Open a box *) @@ -1863,8 +1913,7 @@ let extract_global_decl (ctx : extraction_ctx) (fmt : F.formatter) (fun fmt -> let body = match !backend with - | FStar -> "eval_global " ^ body_name - | Lean -> "eval_global " ^ body_name ^ " (by decide)" + | FStar | Lean -> "eval_global " ^ body_name | Coq -> body_name ^ "%global" | HOL4 -> "get_return_value " ^ body_name in |