I added and alternate syntax for blocks of instructions.

The syntax: block { ... }
The other syntax: begin ... end
This implies adding a new keyword to LIGO: "block".

AST.ml

@@ -41,6 +41,7 @@ let sepseq_to_region to_region = function
 
 type kwd_and        = Region.t
 type kwd_begin      = Region.t
+type kwd_block      = Region.t
 type kwd_case       = Region.t
 type kwd_const      = Region.t
 type kwd_contains   = Region.t
@@ -204,7 +205,7 @@ and record_type = {
   opening     : kwd_record;
   field_decls : field_decls;
   terminator  : semi option;
-  close       : kwd_end
+  closing     : kwd_end
 }
 
 and field_decls = (field_decl reg, semi) nsepseq
@@ -297,12 +298,20 @@ and param_var = {
 }
 
 and block = {
-  opening    : kwd_begin;
+  opening    : block_opening;
   instr      : instructions;
   terminator : semi option;
-  close      : kwd_end
+  closing    : block_closing
 }
 
+and block_opening =
+  Block of kwd_block * lbrace
+| Begin of kwd_begin
+
+and block_closing =
+  Block of rbrace
+| End   of kwd_end
+
 and local_decl =
   LocalLam   of lambda_decl
 | LocalConst of const_decl reg
@@ -372,7 +381,7 @@ and map_injection = {
   opening    : kwd_map;
   bindings   : (binding reg, semi) nsepseq;
   terminator : semi option;
-  close      : kwd_end
+  closing    : kwd_end
 }
 
 and binding = {
@@ -508,7 +517,7 @@ and set_injection = {
   opening    : kwd_set;
   elements   : (expr, semi) nsepseq;
   terminator : semi option;
-  close      : kwd_end
+  closing    : kwd_end
 }
 
 and map_expr =
@@ -585,7 +594,7 @@ and record_injection = {
   opening    : kwd_record;
   fields     : (field_assign reg, semi) nsepseq;
   terminator : semi option;
-  close      : kwd_end
+  closing    : kwd_end
 }
 
 and field_assign = {
@@ -875,11 +884,11 @@ and print_sum_type {value; _} =
   print_nsepseq "|" print_variant value
 
 and print_record_type {value; _} =
-  let {opening; field_decls; terminator; close} = value in
+  let {opening; field_decls; terminator; closing} = value in
   print_token       opening "record";
   print_field_decls field_decls;
   print_terminator  terminator;
-  print_token       close "end"
+  print_token       closing "end"
 
 and print_type_app {value; _} =
   let type_name, type_tuple = value in
@@ -998,11 +1007,20 @@ and print_param_var {value; _} =
   print_type_expr param_type
 
 and print_block {value; _} =
-  let {opening; instr; terminator; close} = value in
+  let {opening; instr; terminator; closing} = value in
-  print_token        opening "begin";
+  print_block_opening opening;
   print_instructions  instr;
   print_terminator    terminator;
-  print_token        close "end"
+  print_block_closing closing
+
+and print_block_opening = function
+  Block (kwd_block, lbrace) -> print_token kwd_block "block";
+                              print_token lbrace    "{"
+| Begin kwd_begin           -> print_token kwd_begin "begin"
+
+and print_block_closing = function
+  Block rbrace -> print_token rbrace "}"
+| End kwd_end  -> print_token kwd_end "end"
 
 and print_local_decls sequence =
   List.iter print_local_decl sequence
@@ -1260,11 +1278,11 @@ and print_record_expr = function
 | RecordProj e -> print_record_projection e
 
 and print_record_injection {value; _} =
-  let {opening; fields; terminator; close} = value in
+  let {opening; fields; terminator; closing} = value in
   print_token opening "record";
   print_nsepseq ";" print_field_assign fields;
   print_terminator terminator;
-  print_token close "end"
+  print_token closing "end"
 
 and print_field_assign {value; _} =
   let {field_name; equal; field_expr} = value in
@@ -1319,18 +1337,18 @@ and print_set_remove node =
   print_path  set
 
 and print_map_injection {value; _} =
-  let {opening; bindings; terminator; close} = value in
+  let {opening; bindings; terminator; closing} = value in
   print_token opening "map";
   print_nsepseq ";" print_binding bindings;
   print_terminator terminator;
-  print_token close "end"
+  print_token closing "end"
 
 and print_set_injection {value; _} =
-  let {opening; elements; terminator; close} = value in
+  let {opening; elements; terminator; closing} = value in
   print_token opening "set";
   print_nsepseq ";" print_expr elements;
   print_terminator terminator;
-  print_token close "end"
+  print_token closing "end"
 
 and print_binding {value; _} =
   let {source; arrow; image} = value in

AST.mli

@@ -25,6 +25,7 @@ val sepseq_to_region  : ('a -> Region.t) -> ('a,'sep) sepseq -> Region.t
 
 type kwd_and        = Region.t
 type kwd_begin      = Region.t
+type kwd_block      = Region.t
 type kwd_case       = Region.t
 type kwd_const      = Region.t
 type kwd_contains   = Region.t
@@ -188,7 +189,7 @@ and record_type = {
   opening     : kwd_record;
   field_decls : field_decls;
   terminator  : semi option;
-  close       : kwd_end
+  closing     : kwd_end
 }
 
 and field_decls = (field_decl reg, semi) nsepseq
@@ -281,12 +282,20 @@ and param_var = {
 }
 
 and block = {
-  opening    : kwd_begin;
+  opening    : block_opening;
   instr      : instructions;
   terminator : semi option;
-  close      : kwd_end
+  closing    : block_closing
 }
 
+and block_opening =
+  Block of kwd_block * lbrace
+| Begin of kwd_begin
+
+and block_closing =
+  Block of rbrace
+| End   of kwd_end
+
 and local_decl =
   LocalLam   of lambda_decl
 | LocalConst of const_decl reg
@@ -356,7 +365,7 @@ and map_injection = {
   opening    : kwd_map;
   bindings   : (binding reg, semi) nsepseq;
   terminator : semi option;
-  close      : kwd_end
+  closing    : kwd_end
 }
 
 and binding = {
@@ -492,7 +501,7 @@ and set_injection = {
   opening    : kwd_set;
   elements   : (expr, semi) nsepseq;
   terminator : semi option;
-  close      : kwd_end
+  closing    : kwd_end
 }
 
 and map_expr =
@@ -569,7 +578,7 @@ and record_injection = {
   opening    : kwd_record;
   fields     : (field_assign reg, semi) nsepseq;
   terminator : semi option;
-  close      : kwd_end
+  closing    : kwd_end
 }
 
 and field_assign = {

LexToken.mli

@@ -67,6 +67,7 @@ type t =
 
 | And        of Region.t  (* "and"        *)
 | Begin      of Region.t  (* "begin"      *)
+| Block      of Region.t  (* "block"      *)
 | Case       of Region.t  (* "case"       *)
 | Const      of Region.t  (* "const"      *)
 | Contains   of Region.t  (* "contains"   *)

LexToken.mll

@@ -66,6 +66,7 @@ type t =
 
 | And        of Region.t  (* "and"        *)
 | Begin      of Region.t  (* "begin"      *)
+| Block      of Region.t  (* "block"      *)
 | Case       of Region.t  (* "case"       *)
 | Const      of Region.t  (* "const"      *)
 | Contains   of Region.t  (* "contains"   *)
@@ -190,6 +191,7 @@ let proj_token = function
 
 | And        region -> region, "And"
 | Begin      region -> region, "Begin"
+| Block      region -> region, "Block"
 | Case       region -> region, "Case"
 | Const      region -> region, "Const"
 | Contains   region -> region, "Contains"
@@ -279,6 +281,7 @@ let to_lexeme = function
 
 | And        _ -> "and"
 | Begin      _ -> "begin"
+| Block      _ -> "block"
 | Case       _ -> "case"
 | Const      _ -> "const"
 | Contains   _ -> "contains"
@@ -338,6 +341,7 @@ let to_region token = proj_token token |> fst
 let keywords = [
   (fun reg -> And        reg);
   (fun reg -> Begin      reg);
+  (fun reg -> Block      reg);
   (fun reg -> Case       reg);
   (fun reg -> Const      reg);
   (fun reg -> Contains   reg);
@@ -565,6 +569,7 @@ let is_ident = function
 let is_kwd = function
   And        _
 | Begin      _
+| Block      _
 | Case       _
 | Const      _
 | Contains   _

Lexer.mll

@@ -459,7 +459,7 @@ let byte_seq   = byte | byte (byte | '_')* byte
 let bytes      = "0x" (byte_seq? as seq)
 let esc        = "\\n" | "\\\"" | "\\\\" | "\\b"
                | "\\r" | "\\t" | "\\x" byte
-let symbol     = ';' | ',' | '(' | ')'| '[' | ']'
+let symbol     = ';' | ',' | '(' | ')'| '[' | ']' | '{' | '}'
                | '#' | '|' | "->" | ":=" | '=' | ':'
                | '<' | "<=" | '>' | ">=" | "=/="
                | '+' | '-' | '*' | '.' | '_' | '^'

ParToken.mly

@@ -17,6 +17,8 @@
 %token <Region.t> COMMA       (* ","   *)
 %token <Region.t> LPAR        (* "("   *)
 %token <Region.t> RPAR        (* ")"   *)
+%token <Region.t> LBRACE      (* "{"   *)
+%token <Region.t> RBRACE      (* "}"   *)
 %token <Region.t> LBRACKET    (* "["   *)
 %token <Region.t> RBRACKET    (* "]"   *)
 %token <Region.t> CONS        (* "#"   *)
@@ -42,6 +44,7 @@
 
 %token <Region.t> And         (* "and"        *)
 %token <Region.t> Begin       (* "begin"      *)
+%token <Region.t> Block       (* "block"      *)
 %token <Region.t> Case        (* "case"       *)
 %token <Region.t> Const       (* "const"      *)
 %token <Region.t> Contains    (* "contains"   *)

Parser.mly

@@ -21,32 +21,32 @@ open AST
 
 (* RULES *)
 
-(* The rule [series(Item)] parses a list of [Item] separated by
+(* The rule [series(Item,TERM)] parses a list of [Item] separated by
-   semi-colons and optionally terminated by a semi-colon, then the
+   semicolons and optionally terminated by a semicolon, then the
-   keyword [End]. *)
+   terminal TERM. *)
 
-series(Item):
+series(Item,TERM):
-  Item after_item(Item) { $1,$2 }
+  Item after_item(Item,TERM) { $1,$2 }
 
-after_item(Item):
+after_item(Item,TERM):
-  SEMI item_or_end(Item) {
+  SEMI item_or_closing(Item,TERM) {
     match $2 with
-      `Some (item, items, term, close) ->
+      `Some (item, items, term, closing) ->
-        ($1, item)::items, term, close
+        ($1, item)::items, term, closing
-    | `End close ->
+    | `Closing closing ->
-        [], Some $1, close
+        [], Some $1, closing
   }
-| End {
+| TERM {
    [], None, $1
   }
 
-item_or_end(Item):
+item_or_closing(Item,TERM):
-  End {
+  TERM {
-   `End $1
+   `Closing $1
   }
-| series(Item) {
+| series(Item,TERM) {
-    let item, (items, term, close) = $1
+    let item, (items, term, closing) = $1
-    in `Some (item, items, term, close)
+    in `Some (item, items, term, closing)
   }
 
 (* Compound constructs *)
@@ -198,14 +198,14 @@ variant:
   }
 
 record_type:
-  Record series(field_decl) {
+  Record series(field_decl,End) {
-   let first, (others, terminator, close) = $2 in
+   let first, (others, terminator, closing) = $2 in
-   let region = cover $1 close
+   let region = cover $1 closing
    and value  = {
      opening = $1;
      field_decls = first, others;
      terminator;
-     close}
+     closing}
    in {region; value}
   }
 
@@ -356,14 +356,24 @@ core_param_type:
   }
 
 block:
-  Begin series(instruction) {
+  Begin series(instruction,End) {
-   let first, (others, terminator, close) = $2 in
+   let first, (others, terminator, closing) = $2 in
-   let region = cover $1 close
+   let region = cover $1 closing
    and value = {
-     opening = $1;
+     opening = Begin $1;
      instr   = first, others;
      terminator;
-     close}
+     closing = End closing}
+   in {region; value}
+  }
+| Block LBRACE series(instruction,RBRACE) {
+   let first, (others, terminator, closing) = $3 in
+   let region = cover $1 closing
+   and value = {
+     opening = Block ($1,$2);
+     instr   = first, others;
+     terminator;
+     closing = Block closing}
    in {region; value}
   }
 
@@ -449,10 +459,9 @@ extended_expr:
 | map_injection     { {region = $1.region; value = `EMap $1} }
 | set_injection     { {region = $1.region; value = `ESet $1} }
 
-
 instruction:
   single_instr { Single $1 }
-| block        { Block  $1 }
+| block        { Block  $1 : instruction }
 
 single_instr:
   conditional  {        Cond $1 }
@@ -515,26 +524,26 @@ map_patch:
   }
 
 set_injection:
-  Set series(expr) {
+  Set series(expr,End) {
-    let first, (others, terminator, close) = $2 in
+    let first, (others, terminator, closing) = $2 in
-    let region = cover $1 close
+    let region = cover $1 closing
     and value = {
       opening  = $1;
       elements = first, others;
       terminator;
-      close}
+      closing}
     in {region; value}
   }
 
 map_injection:
-  Map series(binding) {
+  Map series(binding,End) {
-    let first, (others, terminator, close) = $2 in
+    let first, (others, terminator, closing) = $2 in
-    let region = cover $1 close
+    let region = cover $1 closing
     and value = {
       opening  = $1;
       bindings = first, others;
       terminator;
-      close}
+      closing}
     in {region; value}
   }
 
@@ -885,14 +894,14 @@ record_expr:
 | record_projection { RecordProj $1 }
 
 record_injection:
-  Record series(field_assignment) {
+  Record series(field_assignment,End) {
-    let first, (others, terminator, close) = $2 in
+    let first, (others, terminator, closing) = $2 in
-    let region = cover $1 close
+    let region = cover $1 closing
     and value = {
       opening = $1;
       fields  = first, others;
       terminator;
-      close}
+      closing}
     in {region; value}
   }
 

Tests/crowdfunding.ligo

@@ -11,7 +11,7 @@ entrypoint contribute (storage store : store;
                        const amount  : mutez)
   : store * list (operation) is
   var operations : list (operation) := []
-  begin
+  block {
     if now > store.deadline then
       fail "Deadline passed";
     else
@@ -20,14 +20,14 @@ entrypoint contribute (storage store : store;
 //        None -> patch store.backers with map sender -> amount end
       |    _ -> skip
       end
-  end with (store, operations)
+  } with (store, operations)
 
 entrypoint withdraw (storage store : store; const sender : address)
   : store * list (operation) is
   var operations : list (operation) := []
   begin
     if sender = owner then
-      if now >= store.deadline then
+      if now (Unit) >= store.deadline then
         if balance >= store.goal then
           begin
              store.funded := True;