RFC: regularize Dict syntax

NEWS.md

@@ -20,6 +20,15 @@ Language changes
 
   * `Nothing` (the type of `nothing`) is renamed to `Void` ([#8423]).
 
+  * `Dict` literal syntax `[a=>b,c=>d]` is replaced with `Dict(a=>b,c=>d)`.
+    `{a=>b}` is replaced with `Dict{Any,Any}(a=>b)`.
+    `(K=>V)[...]` is replaced with `Dict{K,V}(...)`.
+    The new syntax has many advantages: all of its components are first-class,
+    it generalizes to other types of containers, it is easier to guess how to
+    specify key and value types, and the syntaxes for empty and pre-populated
+    dicts are synchronized. As part of this change, `=>` is parsed as a normal
+    operator, and `Base` defines it to construct `Pair` objects ([#6739]).
+
 Library improvements
 --------------------
 
@@ -74,7 +83,7 @@ New language features
     generated. Constructors that look like `MyType(a, b) = new(a, b)` do not
     need to be added manually ([#4026], [#7071]).
 
-  * Expanded array type hierarchy to include an abstract ``DenseArray`` for
+  * Expanded array type hierarchy to include an abstract `DenseArray` for
     in-memory arrays with standard strided storage ([#987], [#2345],
     [#6212]).
 
@@ -199,8 +208,8 @@ Library improvements
 
     * `writedlm` and `writecsv` now accept any iterable collection of
       iterable rows, in addition to `AbstractArray` arguments, and the
-      ``writedlm`` delimiter can be any printable object (e.g. a
-      ``String``) instead of just a ``Char``.
+      `writedlm` delimiter can be any printable object (e.g. a
+      `String`) instead of just a `Char`.
 
     * `isempty` now works for any iterable collection ([#5827]).
 
@@ -991,3 +1000,4 @@ Too numerous to mention.
 [#7311]: https://github.com/JuliaLang/julia/issues/7311
 [#8423]: https://github.com/JuliaLang/julia/issues/8423
 [#8152]: https://github.com/JuliaLang/julia/pull/8152
+[#6739]: https://github.com/JuliaLang/julia/issues/6739

base/LineEdit.jl

@@ -5,7 +5,7 @@ using ..Terminals
 import ..Terminals: raw!, width, height, cmove, getX,
                        getY, clear_line, beep
 
-import Base: ensureroom, peek, show
+import Base: ensureroom, peek, show, AnyDict
 
 abstract TextInterface
 
@@ -835,7 +835,7 @@ end
 
 const escape_defaults = merge!(
     {char(i) => nothing for i=[1:26, 28:31]}, # Ignore control characters by default
-    { # And ignore other escape sequences by default
+    AnyDict( # And ignore other escape sequences by default
     "\e*" => nothing,
     "\e[*" => nothing,
     # Also ignore extended escape sequences
@@ -856,7 +856,7 @@ const escape_defaults = merge!(
     "\eOD"  => "\e[D",
     "\eOH"  => "\e[H",
     "\eOF"  => "\e[F",
-})
+))
 
 function write_response_buffer(s::PromptState, data)
     offset = s.input_buffer.ptr
@@ -997,7 +997,7 @@ end
 
 function setup_search_keymap(hp)
     p = HistoryPrompt(hp)
-    pkeymap = {
+    pkeymap = AnyDict(
         "^R"      => (s,data,c)->(history_set_backward(data, true); history_next_result(s, data)),
         "^S"      => (s,data,c)->(history_set_backward(data, false); history_next_result(s, data)),
         '\r'      => (s,o...)->accept_result(s, p),
@@ -1066,12 +1066,12 @@ function setup_search_keymap(hp)
             edit_insert(data.query_buffer, input); update_display_buffer(s, data)
         end,
         "*"       => (s,data,c)->(edit_insert(data.query_buffer, c); update_display_buffer(s, data))
-    }
+    )
     p.keymap_func = keymap([pkeymap, escape_defaults])
-    skeymap = {
+    skeymap = AnyDict(
         "^R"    => (s,o...)->(enter_search(s, p, true)),
         "^S"    => (s,o...)->(enter_search(s, p, false)),
-    }
+    )
     (p, skeymap)
 end
 
@@ -1118,7 +1118,7 @@ function commit_line(s)
 end
 
 const default_keymap =
-{
+AnyDict(
     # Tab
     '\t' => (s,o...)->begin
         buf = buffer(s)
@@ -1226,9 +1226,9 @@ const default_keymap =
         edit_insert(s, input)
     end,
     "^T" => (s,o...)->edit_transpose(s),
-}
+)
 
-const history_keymap = {
+const history_keymap = AnyDict(
     "^P" => (s,o...)->(history_prev(s, mode(s).hist)),
     "^N" => (s,o...)->(history_next(s, mode(s).hist)),
     # Up Arrow
@@ -1239,7 +1239,7 @@ const history_keymap = {
     "\e[5~" => (s,o...)->(history_prev(s, mode(s).hist)),
     # Page Down
     "\e[6~" => (s,o...)->(history_next(s, mode(s).hist))
-}
+)
 
 function deactivate(p::Union(Prompt,HistoryPrompt), s::Union(SearchState,PromptState), termbuf)
     clear_input_area(termbuf, s)

base/REPL.jl

@@ -14,7 +14,8 @@ import Base:
     AsyncStream,
     Display,
     display,
-    writemime
+    writemime,
+    AnyDict
 
 import ..LineEdit:
     CompletionProvider,
@@ -675,9 +676,9 @@ function setup_interface(repl::LineEditREPL; hascolor = repl.hascolor, extra_rep
 
     # Setup history
     # We will have a unified history for all REPL modes
-    hp = REPLHistoryProvider((Symbol=>Any)[:julia => julia_prompt,
-                                           :shell => shell_mode,
-                                           :help  => help_mode])
+    hp = REPLHistoryProvider(Dict{Symbol,Any}(:julia => julia_prompt,
+                                              :shell => shell_mode,
+                                              :help  => help_mode))
     if !repl.no_history_file
         try
             f = open(find_hist_file(), true, true, true, false, false)
@@ -704,7 +705,7 @@ function setup_interface(repl::LineEditREPL; hascolor = repl.hascolor, extra_rep
         extra_repl_keymap = [extra_repl_keymap]
     end
 
-    const repl_keymap = {
+    const repl_keymap = AnyDict(
         ';' => function (s,o...)
             if isempty(s) || position(LineEdit.buffer(s)) == 0
                 buf = copy(LineEdit.buffer(s))
@@ -775,14 +776,14 @@ function setup_interface(repl::LineEditREPL; hascolor = repl.hascolor, extra_rep
                 end
             end
         end,
-    }
+    )
 
     a = Dict{Any,Any}[hkeymap, repl_keymap, LineEdit.history_keymap, LineEdit.default_keymap, LineEdit.escape_defaults]
     prepend!(a, extra_repl_keymap)
 
     julia_prompt.keymap_func = LineEdit.keymap(a)
 
-    const mode_keymap = {
+    const mode_keymap = AnyDict(
         '\b' => function (s,o...)
             if isempty(s) || position(LineEdit.buffer(s)) == 0
                 buf = copy(LineEdit.buffer(s))
@@ -801,7 +802,7 @@ function setup_interface(repl::LineEditREPL; hascolor = repl.hascolor, extra_rep
             transition(s, :reset)
             LineEdit.refresh_line(s)
         end
-    }
+    )
 
     b = Dict{Any,Any}[hkeymap, mode_keymap, LineEdit.history_keymap, LineEdit.default_keymap, LineEdit.escape_defaults]
     prepend!(b, extra_repl_keymap)

base/cartesian.jl

@@ -451,10 +451,10 @@ end
 
 ## Resolve expressions at parsing time ##
 
-const exprresolve_arith_dict = (Symbol=>Function)[:+ => +,
-    :- => -, :* => *, :/ => /, :^ => ^, :div => div]
-const exprresolve_cond_dict = (Symbol=>Function)[:(==) => ==,
-    :(<) => <, :(>) => >, :(<=) => <=, :(>=) => >=]
+const exprresolve_arith_dict = Dict{Symbol,Function}(:+ => +,
+    :- => -, :* => *, :/ => /, :^ => ^, :div => div)
+const exprresolve_cond_dict = Dict{Symbol,Function}(:(==) => ==,
+    :(<) => <, :(>) => >, :(<=) => <=, :(>=) => >=)
 
 function exprresolve_arith(ex::Expr)
     if ex.head == :call && haskey(exprresolve_arith_dict, ex.args[1]) && all([isa(ex.args[i], Number) for i = 2:length(ex.args)])

base/client.jl

@@ -3,7 +3,7 @@
 
 const ARGS = UTF8String[]
 
-const text_colors = {
+const text_colors = AnyDict(
     :black   => "\033[1m\033[30m",
     :red     => "\033[1m\033[31m",
     :green   => "\033[1m\033[32m",
@@ -14,7 +14,7 @@ const text_colors = {
     :white   => "\033[1m\033[37m",
     :normal  => "\033[0m",
     :bold    => "\033[1m",
-}
+)
 
 have_color = false
 @unix_only default_color_answer = text_colors[:bold]

base/collections.jl

@@ -1,11 +1,9 @@
-
 module Collections
 
 import Base: setindex!, done, get, hash, haskey, isempty, length, next, getindex, start
 import ..Order: Forward, Ordering, lt
 
 export
-    Pair,
     PriorityQueue,
     dequeue!,
     enqueue!,
@@ -107,17 +105,6 @@ end
 # PriorityQueue
 # -------------
 
-immutable Pair{A,B}
-    a::A
-    b::B
-end
-
-function hash(p::Pair, h::Uint)
-    h = hash(p.a, h)
-    hash(p.b, h)
-end
-hash(p::Pair) = hash(p, zero(Uint))
-
 # A PriorityQueue that acts like a Dict, mapping values to their priorities,
 # with the addition of a dequeue! function to remove the lowest priority
 # element.
@@ -179,23 +166,23 @@ PriorityQueue{K,V}(a::AbstractArray{(K,V)}, o::Ordering=Forward) = PriorityQueue
 length(pq::PriorityQueue) = length(pq.xs)
 isempty(pq::PriorityQueue) = isempty(pq.xs)
 haskey(pq::PriorityQueue, key) = haskey(pq.index, key)
-peek(pq::PriorityQueue) = (kv = pq.xs[1]; (kv.a, kv.b))
+peek(pq::PriorityQueue) = (kv = pq.xs[1]; (kv.first, kv.second))
 
 
 function percolate_down!(pq::PriorityQueue, i::Integer)
     x = pq.xs[i]
     @inbounds while (l = heapleft(i)) <= length(pq)
         r = heapright(i)
-        j = r > length(pq) || lt(pq.o, pq.xs[l].b, pq.xs[r].b) ? l : r
-        if lt(pq.o, pq.xs[j].b, x.b)
-            pq.index[pq.xs[j].a] = i
+        j = r > length(pq) || lt(pq.o, pq.xs[l].second, pq.xs[r].second) ? l : r
+        if lt(pq.o, pq.xs[j].second, x.second)
+            pq.index[pq.xs[j].first] = i
             pq.xs[i] = pq.xs[j]
             i = j
         else
             break
         end
     end
-    pq.index[x.a] = i
+    pq.index[x.first] = i
     pq.xs[i] = x
 end
 
@@ -204,15 +191,15 @@ function percolate_up!(pq::PriorityQueue, i::Integer)
     x = pq.xs[i]
     @inbounds while i > 1
         j = heapparent(i)
-        if lt(pq.o, x.b, pq.xs[j].b)
-            pq.index[pq.xs[j].a] = i
+        if lt(pq.o, x.second, pq.xs[j].second)
+            pq.index[pq.xs[j].first] = i
             pq.xs[i] = pq.xs[j]
             i = j
         else
             break
         end
     end
-    pq.index[x.a] = i
+    pq.index[x.first] = i
     pq.xs[i] = x
 end
 
@@ -221,30 +208,30 @@ function force_up!(pq::PriorityQueue, i::Integer)
     x = pq.xs[i]
     @inbounds while i > 1
         j = heapparent(i)
-        pq.index[pq.xs[j].a] = i
+        pq.index[pq.xs[j].first] = i
         pq.xs[i] = pq.xs[j]
         i = j
     end
-    pq.index[x.a] = i
+    pq.index[x.first] = i
     pq.xs[i] = x
 end
 
 function getindex{K,V}(pq::PriorityQueue{K,V}, key)
-    pq.xs[pq.index[key]].b
+    pq.xs[pq.index[key]].second
 end
 
 
 function get{K,V}(pq::PriorityQueue{K,V}, key, deflt)
     i = get(pq.index, key, 0)
-    i == 0 ? deflt : pq.xs[i].b
+    i == 0 ? deflt : pq.xs[i].second
 end
 
 
 # Change the priority of an existing element, or equeue it if it isn't present.
 function setindex!{K,V}(pq::PriorityQueue{K, V}, value, key)
     if haskey(pq, key)
         i = pq.index[key]
-        oldvalue = pq.xs[i].b
+        oldvalue = pq.xs[i].second
         pq.xs[i] = Pair{K,V}(key, value)
         if lt(pq.o, oldvalue, value)
             percolate_down!(pq, i)
@@ -275,11 +262,11 @@ function dequeue!(pq::PriorityQueue)
     y = pop!(pq.xs)
     if !isempty(pq)
         pq.xs[1] = y
-        pq.index[y.a] = 1
+        pq.index[y.first] = 1
         percolate_down!(pq, 1)
     end
-    delete!(pq.index, x.a)
-    x.a
+    delete!(pq.index, x.first)
+    x.first
 end
 
 function dequeue!(pq::PriorityQueue, key)
@@ -297,7 +284,7 @@ done(pq::PriorityQueue, i) = done(pq.index, i)
 
 function next(pq::PriorityQueue, i)
     (k, idx), i = next(pq.index, i)
-    return ((k, pq.xs[idx].b), i)
+    return ((k, pq.xs[idx].second), i)
 end
 
 

base/combinatorics.jl

@@ -354,7 +354,7 @@ function nextpartition(n, as)
     xs
 end
 
-let _npartitions = (Int=>Int)[]
+let _npartitions = Dict{Int,Int}()
     global npartitions
     function npartitions(n::Int)
         if n < 0
@@ -424,7 +424,7 @@ function nextfixedpartition(n, m, bs)
     return as
 end
 
-let _nipartitions = ((Int,Int)=>Int)[]
+let _nipartitions = Dict{(Int,Int),Int}()
     global npartitions
     function npartitions(n::Int,m::Int)
         if n < m || m == 0
@@ -489,7 +489,7 @@ function nextsetpartition(s::AbstractVector, a, b, n, m)
 
 end
 
-let _nsetpartitions = (Int=>Int)[]
+let _nsetpartitions = Dict{Int,Int}()
     global nsetpartitions
     function nsetpartitions(n::Int)
         if n < 0

base/datafmt.jl

@@ -285,7 +285,7 @@ end
 
 const valid_opts = [:header, :has_header, :ignore_invalid_chars, :use_mmap, :quotes, :comments, :dims, :comment_char, :skipstart, :skipblanks]
 const valid_opt_types = [Bool, Bool, Bool, Bool, Bool, Bool, NTuple{2,Integer}, Char, Integer, Bool]
-const deprecated_opts = [ :has_header => :header ]
+const deprecated_opts = Dict(:has_header => :header)
 function val_opts(opts)
     d = Dict{Symbol,Union(Bool,NTuple{2,Integer},Char,Integer)}()
     for (opt_name, opt_val) in opts