Use unicode math glyphs instead of square brackets

[ohir]

Square brackets cause too much of cognitive overload. Angle brackets are used everywhere but
are ugly. Though math angle brackets are both readable and lean (IMO).

Go from the inset uses unicode sources. Why not to use other characters for the "generic type" block?
Mac/Linux and vim users have no problem with adding anything under bracket keys (with alt or meta mod). On windows keys can be mapped within IDEs.

Examples with a few runes from the math unicode range follows:

// Eg. unicode     unicode name

// ⟨T⟩ 27e8 27e9   math angle brackets
// ∘T∘ 2218        ring op
// ∫T∫ 222b        integral
// ⟅T⟆ 27c5 27c6   bag left/right

/////////////////////////////////////
// with : ⟨T⟩
type Box⟨T⟩ struct {
  v T
}

func (b Box⟨T⟩) Val() T {
  return b.v
}

func (b Box⟨T⟩) Map⟨U⟩ (f func(T) U) Box⟨U⟩ {
  return Box⟨U⟩{
    v: f(b.v),
  }
}

x := Box⟨string⟩{ v: "foo" }
x.Val()

y := Box⟨int⟩ { v: 42 }
z := y.Map⟨string⟩(strconv.Itoa)

/////////////////////////////////////
// with : ∘T∘
type Box∘T∘ struct {
  v T
}

func (b Box∘T∘) Val() T {
  return b.v
}

func (b Box∘T∘) Map∘U∘ (f func(T) U) Box∘U∘ {
  return Box∘U∘{
    v: f(b.v),
  }
}

x := Box∘string∘{ v: "foo" }
x.Val()

y := Box∘int∘ { v: 42 }
z := y.Map∘string∘(strconv.Itoa)


/////////////////////////////////////
// with : ∫T∫
type Box∫T∫ struct {
  v T
}

func (b Box∫T∫) Val() T {
  return b.v
}

func (b Box∫T∫) Map∫U∫ (f func(T) U) Box∫U∫ {
  return Box∫U∫{
    v: f(b.v),
  }
}

x := Box∫string∫{ v: "foo" }
x.Val()

y := Box∫int∫ { v: 42 }
z := y.Map∫string∫(strconv.Itoa)

/////////////////////////////////////
// with : ⟅T⟆
type Box⟅T⟆ struct {
  v T
}

func (b Box⟅T⟆) Val() T {
  return b.v
}

func (b Box⟅T⟆) Map⟅U⟆ (f func(T) U) Box⟅U⟆ {
  return Box⟅U⟆{
    v: f(b.v),
  }
}

x := Box⟅string⟆{ v: "foo" }
x.Val()

y := Box⟅int⟆ { v: 42 }
z := y.Map⟅string⟆(strconv.Itoa)

[NullVoxPopuli]

the math angle brackets look almost like parenthesis.

(T) vs ⟨T⟩ vs <T>

A picture, in case you have a weird font:

[albrow]

Let's move all discussion about type parameter and type argument syntax to #10. Closing this as a duplicate.