Fleshing out result methods

src/libcore/result.rs

@@ -107,6 +107,79 @@ fn chain_err<T: copy, U: copy, V: copy>(
     }
 }
 
+#[doc = "
+Call a function based on a previous result
+
+If `res` is `ok` then the value is extracted and passed to `op` whereupon
+`op`s result is returned. if `res` is `err` then it is immediately returned.
+This function can be used to compose the results of two functions.
+
+Example:
+
+    iter(read_file(file)) { |buf|
+        print_buf(buf)
+    }
+"]
+fn iter<T, E>(res: result<T, E>, f: fn(T)) {
+    alt res {
+      ok(t) { f(t) }
+      err(_) { }
+    }
+}
+
+#[doc = "
+Call a function based on a previous result
+
+If `res` is `err` then the value is extracted and passed to `op` whereupon
+`op`s result is returned. if `res` is `ok` then it is immediately returned.
+This function can be used to pass through a successful result while handling
+an error.
+"]
+fn iter_err<T, E>(res: result<T, E>, f: fn(E)) {
+    alt res {
+      ok(_) { }
+      err(e) { f(e) }
+    }
+}
+
+#[doc = "
+Call a function based on a previous result
+
+If `res` is `ok` then the value is extracted and passed to `op` whereupon
+`op`s result is wrapped in `ok` and returned. if `res` is `err` then it is
+immediately returned.  This function can be used to compose the results of two
+functions.
+
+Example:
+
+    let res = map(read_file(file)) { |buf|
+        parse_buf(buf)
+    }
+"]
+fn map<T, E: copy, U: copy>(res: result<T, E>, op: fn(T) -> U)
+  -> result<U, E> {
+    alt res {
+      ok(t) { ok(op(t)) }
+      err(e) { err(e) }
+    }
+}
+
+#[doc = "
+Call a function based on a previous result
+
+If `res` is `err` then the value is extracted and passed to `op` whereupon
+`op`s result is wrapped in an `err` and returned. if `res` is `ok` then it is
+immediately returned.  This function can be used to pass through a successful
+result while handling an error.
+"]
+fn map_err<T: copy, E, F: copy>(res: result<T, E>, op: fn(E) -> F)
+  -> result<T, F> {
+    alt res {
+      ok(t) { ok(t) }
+      err(e) { err(op(e)) }
+    }
+}
+
 impl extensions<T:copy, E:copy> for result<T,E> {
     fn get() -> T { get(self) }
 
@@ -123,6 +196,34 @@ impl extensions<T:copy, E:copy> for result<T,E> {
     fn chain_err<F:copy>(op: fn(E) -> result<T,F>) -> result<T,F> {
         chain_err(self, op)
     }
+
+    fn iter(f: fn(T)) {
+        alt self {
+          ok(t) { f(t) }
+          err(_) { }
+        }
+    }
+
+    fn iter_err(f: fn(E)) {
+        alt self {
+          ok(_) { }
+          err(e) { f(e) }
+        }
+    }
+
+    fn map<U:copy>(op: fn(T) -> U) -> result<U,E> {
+        alt self {
+          ok(t) { ok(op(t)) }
+          err(e) { err(e) }
+        }
+    }
+
+    fn map_err<F:copy>(op: fn(E) -> F) -> result<T,F> {
+        alt self {
+          ok(t) { ok(t) }
+          err(e) { err(op(e)) }
+        }
+    }
 }
 
 #[doc = "
@@ -142,7 +243,7 @@ checking for overflow:
         assert incd == [2u, 3u, 4u];
     }
 "]
-fn map<T,U:copy,V:copy>(
+fn map_vec<T,U:copy,V:copy>(
     ts: [T], op: fn(T) -> result<V,U>) -> result<[V],U> {
 
     let mut vs: [V] = [];
@@ -177,7 +278,7 @@ length.  While we do not often use preconditions in the standard
 library, a precondition is used here because result::t is generally
 used in 'careful' code contexts where it is both appropriate and easy
 to accommodate an error like the vectors being of different lengths."]
-fn map2<S,T,U:copy,V:copy>(ss: [S], ts: [T], op: fn(S,T) -> result<V,U>)
+fn map_vec2<S,T,U:copy,V:copy>(ss: [S], ts: [T], op: fn(S,T) -> result<V,U>)
     : vec::same_length(ss, ts) -> result<[V],U> {
 
     let n = vec::len(ts);
@@ -199,8 +300,8 @@ Applies op to the pairwise elements from `ss` and `ts`, aborting on
 error.  This could be implemented using `map2()` but it is more efficient
 on its own as no result vector is built.
 "]
-fn iter2<S,T,U:copy>(ss: [S], ts: [T],
-                     op: fn(S,T) -> result<(),U>)
+fn iter_vec2<S,T,U:copy>(ss: [S], ts: [T],
+                         op: fn(S,T) -> result<(),U>)
     : vec::same_length(ss, ts)
     -> result<(),U> {
 
@@ -248,4 +349,37 @@ mod tests {
     fn chain_failure() {
         assert get_err(chain(op3(), op2)) == "sadface";
     }
+
+    #[test]
+    fn test_impl_iter() {
+        let mut valid = false;
+        ok::<str, str>("a").iter { |_x| valid = true; };
+        assert valid;
+
+        err::<str, str>("b").iter { |_x| valid = false; };
+        assert valid;
+    }
+
+    #[test]
+    fn test_impl_iter_err() {
+        let mut valid = true;
+        ok::<str, str>("a").iter_err { |_x| valid = false; };
+        assert valid;
+
+        valid = false;
+        err::<str, str>("b").iter_err { |_x| valid = true; };
+        assert valid;
+    }
+
+    #[test]
+    fn test_impl_map() {
+        assert ok::<str, str>("a").map { |_x| "b" } == ok("b");
+        assert err::<str, str>("a").map { |_x| "b" } == err("a");
+    }
+
+    #[test]
+    fn test_impl_map_err() {
+        assert ok::<str, str>("a").map_err { |_x| "b" } == ok("a");
+        assert err::<str, str>("a").map_err { |_x| "b" } == err("b");
+    }
 }

src/libstd/json.rs

@@ -16,6 +16,7 @@ export to_str;
 export from_reader;
 export from_str;
 export eq;
+export to_json;
 
 export num;
 export string;
@@ -498,6 +499,110 @@ fn eq(value0: json, value1: json) -> bool {
     }
 }
 
+iface to_json { fn to_json() -> json; }
+
+impl of to_json for json {
+    fn to_json() -> json { self }
+}
+
+impl of to_json for i8 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for i16 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for i32 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for i64 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for u8 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for u16 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for u32 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for u64 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for float {
+    fn to_json() -> json { num(self) }
+}
+
+impl of to_json for f32 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for f64 {
+    fn to_json() -> json { num(self as float) }
+}
+
+impl of to_json for () {
+    fn to_json() -> json { null }
+}
+
+impl of to_json for bool {
+    fn to_json() -> json { boolean(self) }
+}
+
+impl of to_json for str {
+    fn to_json() -> json { string(self) }
+}
+
+impl <A: to_json copy, B: to_json copy> of to_json for (A, B) {
+    fn to_json() -> json {
+        let (a, b) = self;
+        list([a.to_json(), b.to_json()])
+    }
+}
+
+impl <A: to_json copy, B: to_json copy, C: to_json copy>
+  of to_json for (A, B, C) {
+    fn to_json() -> json {
+        let (a, b, c) = self;
+        list([a.to_json(), b.to_json(), c.to_json()])
+    }
+}
+
+impl <A: to_json> of to_json for [A] {
+    fn to_json() -> json { list(self.map { |elt| elt.to_json() }) }
+}
+
+impl <A: to_json copy> of to_json for hashmap<str, A> {
+    fn to_json() -> json {
+        let d = map::str_hash();
+        for self.each() { |key, value|
+            d.insert(key, value.to_json());
+        }
+        dict(d)
+    }
+}
+
+impl <A: to_json> of to_json for option<A> {
+    fn to_json() -> json {
+        alt self {
+          none { null }
+          some(value) { value.to_json() }
+        }
+    }
+}
+
+impl of to_str::to_str for json {
+    fn to_str() -> str { to_str(self) }
+}
+
 #[cfg(test)]
 mod tests {
     fn mk_dict(items: [(str, json)]) -> json {

src/rustc/middle/typeck/infer.rs

@@ -151,7 +151,7 @@ import middle::ty::{ty_vid, tys_in_fn_ty, region_vid, vid};
 import syntax::{ast, ast_util};
 import syntax::ast::{ret_style};
 import util::ppaux::{ty_to_str, mt_to_str};
-import result::{result, extensions, ok, err, map, map2, iter2};
+import result::{result, extensions, ok, err, map_vec, map_vec2, iter_vec2};
 import ty::{mk_fn, type_is_bot};
 import check::regionmanip::{collect_bound_regions_in_tys,
                             replace_bound_regions};
@@ -753,7 +753,7 @@ impl unify_methods for infer_ctxt {
         as: [@ty::type_constr], bs: [@ty::type_constr]) -> ures {
 
         if check vec::same_length(as, bs) {
-            iter2(as, bs) {|a,b|
+            iter_vec2(as, bs) {|a,b|
                 self.constrs(a, b)
             }
         } else {
@@ -1237,7 +1237,9 @@ fn super_tps<C:combine>(
     // variance.
 
     if check vec::same_length(as, bs) {
-        iter2(as, bs) {|a, b| self.infcx().eq_tys(a, b) }.then {||
+        iter_vec2(as, bs) {|a, b|
+            self.infcx().eq_tys(a, b)
+        }.then {||
             ok(as)
         }
     } else {
@@ -1331,7 +1333,7 @@ fn super_fns<C:combine>(
         self: C, a_args: [ty::arg], b_args: [ty::arg]) -> cres<[ty::arg]> {
 
         if check vec::same_length(a_args, b_args) {
-            map2(a_args, b_args) {|a, b| self.args(a, b) }
+            map_vec2(a_args, b_args) {|a, b| self.args(a, b) }
         } else {
             err(ty::terr_arg_count)
         }
@@ -1469,7 +1471,9 @@ fn super_tys<C:combine>(
 
       (ty::ty_rec(as), ty::ty_rec(bs)) {
         if check vec::same_length(as, bs) {
-            map2(as, bs) {|a,b| self.flds(a, b) }.chain {|flds|
+            map_vec2(as, bs) {|a,b|
+                self.flds(a, b)
+            }.chain {|flds|
                 ok(ty::mk_rec(tcx, flds))
             }
         } else {
@@ -1479,7 +1483,7 @@ fn super_tys<C:combine>(
 
       (ty::ty_tup(as), ty::ty_tup(bs)) {
         if check vec::same_length(as, bs) {
-            map2(as, bs) {|a, b| self.tys(a, b) }.chain {|ts|
+            map_vec2(as, bs) {|a, b| self.tys(a, b) }.chain {|ts|
                 ok(ty::mk_tup(tcx, ts))
             }
         } else {