Add and improve type restrictions of block arguments

spec/std/indexable_spec.cr

@@ -8,9 +8,9 @@ private class SafeIndexable
   def initialize(@size : Int32, @offset = 0_i32)
   end
 
-  def unsafe_fetch(i)
+  def unsafe_fetch(i) : Int32
     raise IndexError.new unless 0 <= i < size
-    i + @offset
+    (i + @offset).to_i
   end
 end
 
@@ -22,7 +22,7 @@ private class SafeStringIndexable
   def initialize(@size : Int32)
   end
 
-  def unsafe_fetch(i)
+  def unsafe_fetch(i) : String
     raise IndexError.new unless 0 <= i < size
     i.to_s
   end
@@ -36,7 +36,7 @@ private class SafeMixedIndexable
   def initialize(@size : Int32)
   end
 
-  def unsafe_fetch(i)
+  def unsafe_fetch(i) : String | Int32
     raise IndexError.new unless 0 <= i < size
     i.to_s
   end
@@ -50,7 +50,7 @@ private class SafeRecursiveIndexable
   def initialize(@size : Int32)
   end
 
-  def unsafe_fetch(i)
+  def unsafe_fetch(i) : SafeRecursiveIndexable | Int32
     raise IndexError.new unless 0 <= i < size
     if (i % 2) == 0
       SafeRecursiveIndexable.new(i)

src/array.cr

@@ -153,7 +153,7 @@ class Array(T)
   # ary[0][0] = 2
   # ary # => [[2], [1], [1]]
   # ```
-  def self.new(size : Int, &block : Int32 -> T)
+  def self.new(size : Int, & : Int32 -> T)
     Array(T).build(size) do |buffer|
       size.to_i.times do |i|
         buffer[i] = yield i
@@ -173,7 +173,7 @@ class Array(T)
   #   LibSome.fill_buffer_and_return_number_of_elements_filled(buffer)
   # end
   # ```
-  def self.build(capacity : Int) : self
+  def self.build(capacity : Int, & : Pointer(T) ->) : self
     ary = Array(T).new(capacity)
     ary.size = (yield ary.to_unsafe).to_i
     ary
@@ -1048,7 +1048,7 @@ class Array(T)
   end
 
   # Optimized version of `Enumerable#map`.
-  def map(&block : T -> U) forall U
+  def map(& : T -> U) forall U
     Array(U).new(size) { |i| yield @buffer[i] }
   end
 
@@ -1062,7 +1062,7 @@ class Array(T)
   # ```
   #
   # See also: `Array#select`.
-  def select!
+  def select!(& : T ->) : self
     reject! { |elem| !yield(elem) }
   end
 
@@ -1090,7 +1090,7 @@ class Array(T)
   # ```
   #
   # See also: `Array#reject`.
-  def reject!
+  def reject!(& : T ->) : self
     internal_delete { |e| yield e }
     self
   end
@@ -1151,7 +1151,7 @@ class Array(T)
   # results = gems.map_with_index { |gem, i| "#{i}: #{gem}" }
   # results # => ["0: crystal", "1: pearl", "2: diamond"]
   # ```
-  def map_with_index(offset = 0, &block : T, Int32 -> U) forall U
+  def map_with_index(offset = 0, & : T, Int32 -> U) forall U
     Array(U).new(size) { |i| yield @buffer[i], offset + i }
   end
 
@@ -1350,7 +1350,7 @@ class Array(T)
     result
   end
 
-  def product(enumerable : Enumerable, &block)
+  def product(enumerable : Enumerable(U), & : T, U ->) forall U
     self.each { |a| enumerable.each { |b| yield a, b } }
   end
 
@@ -1874,7 +1874,7 @@ class Array(T)
   # a.uniq { |s| s[0] } # => [{"student", "sam"}, {"teacher", "matz"}]
   # a                   # => [{"student", "sam"}, {"student", "george"}, {"teacher", "matz"}]
   # ```
-  def uniq(&block : T -> _)
+  def uniq(& : T ->)
     if size <= 1
       dup
     else
@@ -1915,7 +1915,7 @@ class Array(T)
   # a.uniq! { |s| s[0] } # => [{"student", "sam"}, {"teacher", "matz"}]
   # a                    # => [{"student", "sam"}, {"teacher", "matz"}]
   # ```
-  def uniq!
+  def uniq!(& : T ->) : self
     if size <= 1
       return self
     end
@@ -2150,7 +2150,7 @@ class Array(T)
     to_lookup_hash { |elem| elem }
   end
 
-  protected def to_lookup_hash(&block : T -> U) forall U
+  protected def to_lookup_hash(& : T -> U) forall U
     each_with_object(Hash(U, T).new) do |o, h|
       key = yield o
       unless h.has_key?(key)

src/deque.cr

@@ -77,7 +77,7 @@ class Deque(T)
   # ```
   # Deque.new(3) { |i| (i + 1) ** 2 } # => Deque{1, 4, 9}
   # ```
-  def self.new(size : Int, &block : Int32 -> T)
+  def self.new(size : Int, & : Int32 -> T)
     if size < 0
       raise ArgumentError.new("Negative deque size: #{size}")
     end
@@ -207,7 +207,7 @@ class Deque(T)
   # ```
   #
   # See also: `Deque#select`.
-  def select!
+  def select!(& : T ->) : self
     reject! { |elem| !yield(elem) }
   end
 
@@ -235,7 +235,7 @@ class Deque(T)
   # ```
   #
   # See also: `Deque#reject`.
-  def reject!
+  def reject!(& : T ->) : self
     internal_delete { |e| yield e }
     self
   end
@@ -338,7 +338,7 @@ class Deque(T)
   # Yields each item in this deque, from first to last.
   #
   # Do not modify the deque while using this variant of `each`!
-  def each : Nil
+  def each(& : T ->) : Nil
     halfs do |r|
       r.each do |i|
         yield @buffer[i]

src/enum.cr

@@ -303,7 +303,7 @@ struct Enum
   #   # yield IOMode::Async, 3
   # end
   # ```
-  def each
+  def each(& : self ->)
     {% if @type.annotation(Flags) %}
       return if value == 0
       {% for member in @type.constants %}
@@ -468,7 +468,7 @@ struct Enum
   #   # yield IOMode::Async, 3
   # end
   # ```
-  def self.each
+  def self.each(& : self ->)
     {% for member in @type.constants %}
       {% unless @type.annotation(Flags) && %w(none all).includes?(member.stringify.downcase) %}
         yield new({{@type.constant(member)}}), {{@type.constant(member)}}