fix(build): track 23 codegen modules referenced by lib/dune

lib/bash_codegen.ml

@@ -0,0 +1,106 @@
+(* SPDX-License-Identifier: PMPL-1.0-or-later *)
+(* SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell *)
+
+(** Bash/POSIX shell emitter (heavily restricted MVP).
+
+    Bash is genuinely limited: no first-class numbers, no closures, no
+    structures. We accept Int-only programs whose entry returns Int (used
+    as the shell exit code). Functions are emitted as Bash functions that
+    [echo] their result; callers read it via [$(fn args)]. *)
+
+open Ast
+
+exception Bash_unsupported of string
+let unsupported m = raise (Bash_unsupported m)
+
+let bash_reserved = [
+  "if"; "then"; "else"; "elif"; "fi"; "case"; "esac";
+  "for"; "while"; "until"; "do"; "done"; "function"; "return";
+  "in"; "break"; "continue"; "exit"; "true"; "false";
+]
+
+let mangle s = if List.mem s bash_reserved then s ^ "_" else s
+
+(* Bash arithmetic only: every expression must evaluate to an integer. *)
+let rec gen_expr (e : expr) : string =
+  match e with
+  | ExprLit (LitInt (n, _))     -> string_of_int n
+  | ExprLit (LitBool (true, _)) -> "1"
+  | ExprLit (LitBool (false, _))-> "0"
+  | ExprLit _ -> unsupported "Bash backend accepts only Int/Bool literals"
+  | ExprVar id -> "$" ^ mangle id.name
+  | ExprBinary (a, op, b) ->
+      let s = match op with
+        | OpAdd -> "+" | OpSub -> "-" | OpMul -> "*" | OpDiv -> "/" | OpMod -> "%"
+        | OpEq  -> "==" | OpNe -> "!="
+        | OpLt  -> "<" | OpLe -> "<=" | OpGt -> ">" | OpGe -> ">="
+        | OpAnd -> "&&" | OpOr -> "||"
+        | OpBitAnd -> "&" | OpBitOr -> "|" | OpBitXor -> "^"
+        | OpShl -> "<<" | OpShr -> ">>"
+        | OpConcat -> unsupported "string concat not supported in Bash backend"
+      in
+      "(" ^ gen_expr a ^ " " ^ s ^ " " ^ gen_expr b ^ ")"
+  | ExprUnary (OpNeg, x) -> "(-" ^ gen_expr x ^ ")"
+  | ExprUnary (OpNot, x) -> "(! " ^ gen_expr x ^ ")"
+  | ExprUnary _ -> unsupported "unary op not supported in Bash backend"
+  | ExprApp (callee, args) ->
+      let name = match callee with
+        | ExprVar id -> id.name
+        | _ -> unsupported "indirect call not supported in Bash backend"
+      in
+      let arg_strs = List.map gen_expr args in
+      (* Call a Bash function and capture its echo: $(fn 1 2) *)
+      Printf.sprintf "$(%s %s)" (mangle name) (String.concat " " arg_strs)
+  | ExprIf { ei_cond; ei_then; ei_else } ->
+      let c = gen_expr ei_cond in
+      let t = gen_expr ei_then in
+      let f = match ei_else with Some e -> gen_expr e | None -> "0" in
+      (* Bash arithmetic ternary: $((c ? t : f)) — works in all $((...)) *)
+      Printf.sprintf "(%s ? %s : %s)" c t f
+  | ExprLet { el_pat = PatVar _; _ } ->
+      unsupported "expression-position let not supported in Bash backend"
+  | ExprSpan (inner, _) -> gen_expr inner
+  | ExprBlock _ -> unsupported "block expressions not supported in Bash backend"
+  | _ -> unsupported "expression form not supported in Bash backend"
+
+let gen_function (fd : fn_decl) : string =
+  let name = mangle fd.fd_name.name in
+  let params = fd.fd_params in
+  let body_expr = match fd.fd_body with
+    | FnExpr e -> e
+    | FnBlock { blk_stmts = []; blk_expr = Some e } -> e
+    | FnBlock _ ->
+        unsupported "Bash backend accepts only single-expression function bodies"
+  in
+  let body_str = gen_expr body_expr in
+  let buf = Buffer.create 128 in
+  Buffer.add_string buf (name ^ "() {\n");
+  List.iteri (fun i (p : param) ->
+    Buffer.add_string buf
+      (Printf.sprintf "  local %s=$%d\n" (mangle p.p_name.name) (i + 1))
+  ) params;
+  Buffer.add_string buf (Printf.sprintf "  echo $((%s))\n}\n\n" body_str);
+  Buffer.contents buf
+
+let generate (program : program) (_symbols : Symbol.t) : string =
+  let buf = Buffer.create 1024 in
+  Buffer.add_string buf "#!/usr/bin/env bash\n";
+  Buffer.add_string buf "# Generated by AffineScript compiler\n";
+  Buffer.add_string buf "# SPDX-License-Identifier: PMPL-1.0-or-later\n";
+  Buffer.add_string buf "set -euo pipefail\n\n";
+  List.iter (function
+    | TopFn fd -> Buffer.add_string buf (gen_function fd)
+    | _ -> ()
+  ) program.prog_decls;
+  let has_main = List.exists (function
+    | TopFn fd -> fd.fd_name.name = "main"
+    | _ -> false) program.prog_decls in
+  if has_main then Buffer.add_string buf "exit $(main)\n";
+  Buffer.contents buf
+
+let codegen_bash (program : program) (symbols : Symbol.t) : (string, string) result =
+  try Ok (generate program symbols)
+  with
+  | Bash_unsupported msg -> Error ("Bash backend: " ^ msg)
+  | Failure msg          -> Error ("Bash codegen error: " ^ msg)
+  | e                    -> Error ("Bash codegen error: " ^ Printexc.to_string e)