---

yaml
---
r: 1011
b: refs/heads/master
c: 0c19c8e
h: refs/heads/master
i:
  1009: 38769c0
  1007: 2b42d1a
v: v3

Author: graydon

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: afd3af9bb58f19323c584417d359d83742ba889f
+refs/heads/master: 0c19c8e18f5e145c379fe4b50e5ea8d44fe4969f

trunk/src/comp/front/ast.rs

@@ -55,6 +55,18 @@ tag mutability {
     imm;
 }
 
+tag layer {
+    layer_value;
+    layer_state;
+    layer_gc;
+}
+
+tag effect {
+    eff_pure;
+    eff_impure;
+    eff_unsafe;
+}
+
 tag binop {
     add;
     sub;
@@ -85,6 +97,11 @@ tag unop {
     neg;
 }
 
+tag mode {
+    val;
+    alias;
+}
+
 type stmt = spanned[stmt_];
 tag stmt_ {
     stmt_decl(@decl);
@@ -146,7 +163,9 @@ tag lit_ {
 
 // NB: If you change this, you'll probably want to change the corresponding
 // type structure in middle/typeck.rs as well.
+
 type ty_field = rec(ident ident, @ty ty);
+type ty_arg = rec(mode mode, @ty ty);
 type ty = spanned[ty_];
 tag ty_ {
     ty_nil;
@@ -160,18 +179,14 @@ tag ty_ {
     ty_vec(@ty);
     ty_tup(vec[@ty]);
     ty_rec(vec[ty_field]);
-    ty_fn(vec[rec(mode mode, @ty ty)], @ty);        // TODO: effect
+    ty_fn(vec[ty_arg], @ty);        // TODO: effect
     ty_path(path, option.t[def]);
     ty_mutable(@ty);
 }
 
-tag mode {
-    val;
-    alias;
-}
-
 type arg = rec(mode mode, @ty ty, ident ident, def_id id);
-type _fn = rec(vec[arg] inputs,
+type _fn = rec(effect effect,
+               vec[arg] inputs,
                @ty output,
                block body);
 

trunk/src/comp/front/parser.rs

@@ -1161,7 +1161,7 @@ impure fn parse_ty_params(parser p) -> vec[ast.ty_param] {
     ret ty_params;
 }
 
-impure fn parse_item_fn(parser p) -> @ast.item {
+impure fn parse_item_fn(parser p, ast.effect eff) -> @ast.item {
     auto lo = p.get_span();
     expect(p, token.FN);
     auto id = parse_ident(p);
@@ -1187,7 +1187,8 @@ impure fn parse_item_fn(parser p) -> @ast.item {
 
     auto body = parse_block(p);
 
-    let ast._fn f = rec(inputs = inputs.node,
+    let ast._fn f = rec(effect = eff,
+                        inputs = inputs.node,
                         output = output,
                         body = body);
 
@@ -1305,18 +1306,61 @@ impure fn parse_item_tag(parser p) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
+impure fn parse_layer(parser p) -> ast.layer {
+    alt (p.peek()) {
+        case (token.STATE) {
+            p.bump();
+            ret ast.layer_state;
+        }
+        case (token.GC) {
+            p.bump();
+            ret ast.layer_gc;
+        }
+        case (_) {
+            ret ast.layer_value;
+        }
+    }
+    fail;
+}
+
+
+impure fn parse_effect(parser p) -> ast.effect {
+    alt (p.peek()) {
+        case (token.IMPURE) {
+            p.bump();
+            ret ast.eff_impure;
+        }
+        case (token.UNSAFE) {
+            p.bump();
+            ret ast.eff_unsafe;
+        }
+        case (_) {
+            ret ast.eff_pure;
+        }
+    }
+    fail;
+}
+
 impure fn parse_item(parser p) -> @ast.item {
+    let ast.effect eff = parse_effect(p);
+    let ast.layer lyr = parse_layer(p);
+
     alt (p.peek()) {
         case (token.FN) {
-            ret parse_item_fn(p);
+            check (lyr == ast.layer_value);
+            ret parse_item_fn(p, eff);
         }
         case (token.MOD) {
+            check (eff == ast.eff_pure);
+            check (lyr == ast.layer_value);
             ret parse_item_mod(p);
         }
         case (token.TYPE) {
+            check (eff == ast.eff_pure);
             ret parse_item_type(p);
         }
         case (token.TAG) {
+            check (eff == ast.eff_pure);
             ret parse_item_tag(p);
         }
         case (?t) {

trunk/src/comp/middle/fold.rs

@@ -185,7 +185,8 @@ type ast_fold[ENV] =
      (fn(&ENV e, &span sp,
          &ast.block_) -> block)                   fold_block,
 
-     (fn(&ENV e, vec[arg] inputs,
+     (fn(&ENV e, ast.effect effect,
+         vec[arg] inputs,
          @ty output, &block body) -> ast._fn)     fold_fn,
 
      (fn(&ENV e, &ast._mod m) -> ast._mod)        fold_mod,
@@ -570,7 +571,7 @@ fn fold_fn[ENV](&ENV env, ast_fold[ENV] fld, &ast._fn f) -> ast._fn {
     auto output = fold_ty[ENV](env, fld, f.output);
     auto body = fold_block[ENV](env, fld, f.body);
 
-    ret fld.fold_fn(env, inputs, output, body);
+    ret fld.fold_fn(env, f.effect, inputs, output, body);
 }
 
 fn fold_item[ENV](&ENV env, ast_fold[ENV] fld, @item i) -> @item {
@@ -891,10 +892,11 @@ fn identity_fold_block[ENV](&ENV e, &span sp, &ast.block_ blk) -> block {
 }
 
 fn identity_fold_fn[ENV](&ENV e,
+                         ast.effect effect,
                          vec[arg] inputs,
                          @ast.ty output,
                          &block body) -> ast._fn {
-    ret rec(inputs=inputs, output=output, body=body);
+    ret rec(effect=effect, inputs=inputs, output=output, body=body);
 }
 
 fn identity_fold_mod[ENV](&ENV e, &ast._mod m) -> ast._mod {
@@ -1007,7 +1009,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_item_tag  = bind identity_fold_item_tag[ENV](_,_,_,_,_,_),
 
          fold_block = bind identity_fold_block[ENV](_,_,_),
-         fold_fn = bind identity_fold_fn[ENV](_,_,_,_),
+         fold_fn = bind identity_fold_fn[ENV](_,_,_,_,_),
          fold_mod = bind identity_fold_mod[ENV](_,_),
          fold_crate = bind identity_fold_crate[ENV](_,_,_),
 

trunk/src/comp/middle/typeck.rs

@@ -1643,7 +1643,8 @@ fn check_fn(&@crate_ctxt ccx, &span sp, ast.ident ident, &ast._fn f,
     auto block_t = check_block(fcx, f.body);
     auto block_wb = writeback(fcx, block_t);
 
-    auto fn_t = rec(inputs=f.inputs, output=f.output, body=block_wb);
+    auto fn_t = rec(effect=f.effect, inputs=f.inputs, output=f.output,
+                    body=block_wb);
     auto item = ast.item_fn(ident, fn_t, ty_params, id, fn_ann);
     ret @fold.respan[ast.item_](sp, item);
 }