diff options
| -rw-r--r-- | Changes | 8 | ||||
| -rw-r--r-- | parsing/lexer.mll | 2 | ||||
| -rw-r--r-- | parsing/parser.mly | 22 |
3 files changed, 32 insertions, 0 deletions
@@ -12,6 +12,14 @@ Language features: Using the -principal option guarantees forward compatibility. - New (module M) and (module M : S) syntax in patterns, for immediate unpacking of a first-class module. +- Let-like operators can now be defined. Syntax for definining + such an operator: let (let!) x f = ...; for using it: let! p = e1 in e2, + sugar for (let!) e1 (fun p -> e2); or with an explicit module qualifier + M.let! p = e1 in e2. Multiple-bindings are allowed (let! p1 = e1 and p2 = e2 + in in e3 is equivalent to let! (p1, p2) = (e1, e2) in e3. The lexical + definition for a let-like operator is the string "let", immediatly followed + by an non-empty sequence of operator characters. + Compilers: - Revised simplification of let-alias (PR#5205, PR#5288) diff --git a/parsing/lexer.mll b/parsing/lexer.mll index 87e2a8cbc..c0ddf023b 100644 --- a/parsing/lexer.mll +++ b/parsing/lexer.mll @@ -402,6 +402,8 @@ rule token = parse { INFIXOP4(Lexing.lexeme lexbuf) } | ['*' '/' '%'] symbolchar * { INFIXOP3(Lexing.lexeme lexbuf) } + | "let" symbolchar+ + { LETOP(Lexing.lexeme lexbuf) } | eof { EOF } | _ { raise (Error(Illegal_character (Lexing.lexeme_char lexbuf 0), diff --git a/parsing/parser.mly b/parsing/parser.mly index 885a581d4..87d43bdab 100644 --- a/parsing/parser.mly +++ b/parsing/parser.mly @@ -319,6 +319,17 @@ let wrap_type_annotation newtypes core_type body = let polyvars, core_type = varify_constructors newtypes core_type in (exp, ghtyp(Ptyp_poly(polyvars,core_type))) +let let_operator op bindings cont = + let pat, expr = + match List.rev bindings with + | [] -> assert false + | [x] -> x + | l -> + let pats, exprs = List.split l in + ghpat (Ppat_tuple pats), ghexp (Pexp_tuple exprs) + in + mkexp(Pexp_apply(op, ["", expr; "", ghexp(Pexp_function("", None, [pat, cont]))])) + %} /* Tokens */ @@ -386,6 +397,7 @@ let wrap_type_annotation newtypes core_type body = %token LESS %token LESSMINUS %token LET +%token <string> LETOP %token <string> LIDENT %token LPAREN %token MATCH @@ -462,6 +474,7 @@ The precedences must be listed from low to high. %nonassoc below_SEMI %nonassoc SEMI /* below EQUAL ({lbl=...; lbl=...}) */ %nonassoc LET /* above SEMI ( ...; let ... in ...) */ +%nonassoc LETOP %nonassoc below_WITH %nonassoc FUNCTION WITH /* below BAR (match ... with ...) */ %nonassoc AND /* above WITH (module rec A: SIG with ... and ...) */ @@ -982,6 +995,8 @@ expr: { mkexp(Pexp_apply($1, List.rev $2)) } | LET rec_flag let_bindings IN seq_expr { mkexp(Pexp_let($2, List.rev $3, $5)) } + | let_operator let_bindings IN seq_expr + { let_operator $1 $2 $4 } | LET MODULE UIDENT module_binding IN seq_expr { mkexp(Pexp_letmodule($3, $4, $6)) } | LET OPEN mod_longident IN seq_expr @@ -1704,6 +1719,7 @@ operator: | INFIXOP2 { $1 } | INFIXOP3 { $1 } | INFIXOP4 { $1 } + | LETOP { $1 } | BANG { "!" } | PLUS { "+" } | PLUSDOT { "+." } @@ -1719,6 +1735,12 @@ operator: | AMPERAMPER { "&&" } | COLONEQUAL { ":=" } ; +let_operator: + LETOP + { mkexp (Pexp_ident(Lident $1)) } + | mod_longident DOT LETOP + { mkexp (Pexp_ident(Ldot ($1, $3))) } +; constr_ident: UIDENT { $1 } /* | LBRACKET RBRACKET { "[]" } */ |