Use eltype(x) everywhere, ignore typeof(η) (#151)

* always convert learning rate to eltype(momentum) before use

* don't parameterise rule structs, just use Float64

* fix tests like === 0.2f0

* fix a constructor

* fix AdamW

* fix Rprop

* use a macro to define structs with default values

* use T = eltype(x)

* a few more structs

* more structs

* fix tests

* doc fixes

* fix docstrings

* skip Yota on nightly

* docstrings

* breaking change, v0.3-dev

* print Adam(0.01f0) without 0.009999999776482582

* Revert "skip Yota on nightly"

This reverts commit abf0e13.

* don't accidentally write to stdout

Project.toml

@@ -1,7 +1,7 @@
 name = "Optimisers"
 uuid = "3bd65402-5787-11e9-1adc-39752487f4e2"
 authors = ["Mike J Innes <mike.j.innes@gmail.com>"]
-version = "0.2.20"
+version = "0.3.0-DEV"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

docs/src/index.md

@@ -7,14 +7,15 @@ These act on one array of parameters:
 
 ```julia
 # Define a container to hold any optimiser specific parameters (if any):
-struct DecayDescent{T} <: Optimisers.AbstractRule
-  eta::T
+struct DecayDescent <: Optimisers.AbstractRule
+  eta::Float64
 end
 
 # Define an `apply!` rule which encodes how the gradients will be used to
 # update the parameters:
 function Optimisers.apply!(o::DecayDescent, state, x, x̄)
-  newx̄ = (o.eta / √state) .* x̄
+  T = eltype(x)
+  newx̄ = T(o.eta / √state) .* x̄
   nextstate = state + 1
   return nextstate, newx̄
 end

src/Optimisers.jl

@@ -78,7 +78,7 @@ or [`update!`](@ref).
 julia> m = (x = rand(3), y = (true, false), z = tanh);
 
 julia> Optimisers.setup(Momentum(), m)  # same field names as m
-(x = Leaf(Momentum{Float32}(0.01, 0.9), [0.0, 0.0, 0.0]), y = ((), ()), z = ())
+(x = Leaf(Momentum(0.01, 0.9), [0.0, 0.0, 0.0]), y = ((), ()), z = ())
 ```
 
 The recursion into structures uses Functors.jl, and any new `struct`s containing parameters
@@ -91,15 +91,15 @@ julia> struct Layer; mat; fun; end
 julia> model = (lay = Layer([1 2; 3 4f0], sin), vec = [5, 6f0]);
 
 julia> Optimisers.setup(Momentum(), model)  # new struct is by default ignored
-(lay = (), vec = Leaf(Momentum{Float32}(0.01, 0.9), Float32[0.0, 0.0]))
+(lay = (), vec = Leaf(Momentum(0.01, 0.9), Float32[0.0, 0.0]))
 
 julia> destructure(model)
 (Float32[5.0, 6.0], Restructure(NamedTuple, ..., 2))
 
 julia> using Functors; @functor Layer  # annotate this type as containing parameters
 
 julia> Optimisers.setup(Momentum(), model)
-(lay = (mat = Leaf(Momentum{Float32}(0.01, 0.9), Float32[0.0 0.0; 0.0 0.0]), fun = ()), vec = Leaf(Momentum{Float32}(0.01, 0.9), Float32[0.0, 0.0]))
+(lay = (mat = Leaf(Momentum(0.01, 0.9), Float32[0.0 0.0; 0.0 0.0]), fun = ()), vec = Leaf(Momentum(0.01, 0.9), Float32[0.0, 0.0]))
 
 julia> destructure(model)
 (Float32[1.0, 3.0, 2.0, 4.0, 5.0, 6.0], Restructure(NamedTuple, ..., 6))
@@ -120,13 +120,13 @@ See also [`update!`](@ref), which will be faster for models of ordinary `Array`s
 ```jldoctest
 julia> m = (x = Float32[1,2,3], y = tanh);
 
-julia> t = Optimisers.setup(Descent(0.1f0), m)
-(x = Leaf(Descent{Float32}(0.1), nothing), y = ())
+julia> t = Optimisers.setup(Descent(0.1), m)
+(x = Leaf(Descent(0.1), nothing), y = ())
 
 julia> g = (x = [1,1,1], y = nothing);  # fake gradient
 
 julia> Optimisers.update(t, m, g)
-((x = Leaf(Descent{Float32}(0.1), nothing), y = ()), (x = Float32[0.9, 1.9, 2.9], y = tanh))
+((x = Leaf(Descent(0.1), nothing), y = ()), (x = Float32[0.9, 1.9, 2.9], y = tanh))
 ```
 """
 update
@@ -152,7 +152,7 @@ julia> using StaticArrays, Zygote, Optimisers
 julia> m = (x = [1f0, 2f0], y = SA[4f0, 5f0]);  # partly mutable model
 
 julia> t = Optimisers.setup(Momentum(1/30, 0.9), m)  # tree of states
-(x = Leaf(Momentum{Float64}(0.0333333, 0.9), Float32[0.0, 0.0]), y = Leaf(Momentum{Float64}(0.0333333, 0.9), Float32[0.0, 0.0]))
+(x = Leaf(Momentum(0.0333333, 0.9), Float32[0.0, 0.0]), y = Leaf(Momentum(0.0333333, 0.9), Float32[0.0, 0.0]))
 
 julia> g = gradient(m -> sum(abs2.(m.x .+ m.y)), m)[1]  # structural gradient
 (x = Float32[10.0, 14.0], y = Float32[10.0, 14.0])

src/adjust.jl

@@ -23,15 +23,15 @@ julia> Optimisers.freeze!(s.x)
 julia> Optimisers.update!(s, m, (x = ([pi], 10pi), y = [100pi]));  # with fake gradient
 
 julia> m
-(x = ([1.0], 2.0), y = [-0.14159258336972558])
+(x = ([1.0], 2.0), y = [-0.14159265358979312])
 
 julia> s
-(x = (Leaf(Momentum{Float32}(0.01, 0.9), [0.0], frozen = true), ()), y = Leaf(Momentum{Float32}(0.01, 0.9), [3.14159]))
+(x = (Leaf(Momentum(0.01, 0.9), [0.0], frozen = true), ()), y = Leaf(Momentum(0.01, 0.9), [3.14159]))
 
 julia> Optimisers.thaw!(s)
 
 julia> s.x
-(Leaf(Momentum{Float32}(0.01, 0.9), [0.0]), ())
+(Leaf(Momentum(0.01, 0.9), [0.0]), ())
 ```
 """
 freeze!(tree) = foreach(freeze!, tree)
@@ -72,17 +72,17 @@ To change just the learning rate, provide a number `η::Real`.
 julia> m = (vec = rand(Float32, 2), fun = sin);
 
 julia> st = Optimisers.setup(Nesterov(), m)  # stored momentum is initialised to zero
-(vec = Leaf(Nesterov{Float32}(0.001, 0.9), Float32[0.0, 0.0]), fun = ())
+(vec = Leaf(Nesterov(0.001, 0.9), Float32[0.0, 0.0]), fun = ())
 
 julia> st, m = Optimisers.update(st, m, (vec = [16, 88], fun = nothing));  # with fake gradient
 
 julia> st
-(vec = Leaf(Nesterov{Float32}(0.001, 0.9), Float32[-0.016, -0.088]), fun = ())
+(vec = Leaf(Nesterov(0.001, 0.9), Float32[-0.016, -0.088]), fun = ())
 
 julia> Optimisers.adjust!(st, 0.123)  # change learning rate, stored momentum untouched
 
 julia> st
-(vec = Leaf(Nesterov{Float32}(0.123, 0.9), Float32[-0.016, -0.088]), fun = ())
+(vec = Leaf(Nesterov(0.123, 0.9), Float32[-0.016, -0.088]), fun = ())
 ```
 
 To change other parameters, `adjust!` also accepts keyword arguments matching the field
@@ -93,13 +93,13 @@ julia> fieldnames(Adam)
 (:eta, :beta, :epsilon)
 
 julia> st2 = Optimisers.setup(OptimiserChain(ClipGrad(), Adam()), m)
-(vec = Leaf(OptimiserChain(ClipGrad{Float32}(10.0), Adam{Float32}(0.001, (0.9, 0.999), 1.19209f-7)), (nothing, (Float32[0.0, 0.0], Float32[0.0, 0.0], (0.9, 0.999)))), fun = ())
+(vec = Leaf(OptimiserChain(ClipGrad(10.0), Adam(0.001, (0.9, 0.999), 1.0e-8)), (nothing, (Float32[0.0, 0.0], Float32[0.0, 0.0], (0.9, 0.999)))), fun = ())
 
 julia> Optimisers.adjust(st2; beta = (0.777, 0.909), delta = 11.1)  # delta acts on ClipGrad
-(vec = Leaf(OptimiserChain(ClipGrad{Float32}(11.1), Adam{Float32}(0.001, (0.777, 0.909), 1.19209f-7)), (nothing, (Float32[0.0, 0.0], Float32[0.0, 0.0], (0.9, 0.999)))), fun = ())
+(vec = Leaf(OptimiserChain(ClipGrad(11.1), Adam(0.001, (0.777, 0.909), 1.0e-8)), (nothing, (Float32[0.0, 0.0], Float32[0.0, 0.0], (0.9, 0.999)))), fun = ())
 
 julia> Optimisers.adjust(st; beta = "no such field")  # silently ignored!
-(vec = Leaf(Nesterov{Float32}(0.123, 0.9), Float32[-0.016, -0.088]), fun = ())
+(vec = Leaf(Nesterov(0.123, 0.9), Float32[-0.016, -0.088]), fun = ())
 ```
 """
 adjust!(tree, eta::Real) = foreach(st -> adjust!(st, eta), tree)

src/interface.jl

@@ -7,6 +7,10 @@ const Zero = Union{Nothing, AbstractZero}  # Union{Zygote, Diffractor}
 
 abstract type AbstractRule end
 
+function Base.show(io::IO, rule::AbstractRule)  # makes Adam(0.01f0) prettier
+  invoke(show, Tuple{IO,Any}, IOContext(io, :compact => true), rule)
+end
+
 ###
 ### setup
 ###
@@ -225,3 +229,42 @@ Broadcast.materialize(x::Lazy) = Broadcast.instantiate(x.bc)
 onevalue(λ::T, x::AbstractArray{T}) where T = map(_ -> λ, x)
 onevalue(λ, x::AbstractArray{T}) where T = onevalue(convert(float(T), λ), x)
 
+nonneg(η::Real) = η < 0 ? throw(DomainError(η, "the learning rate cannot be negative")) : η
+
+"""
+  @def struct Rule; eta = 0.1; beta = (0.7, 0.8); end
+
+Helper macro for defining rules with default values.
+The types of the literal values are used in the `struct`,
+like this:
+```
+struct Rule
+  eta::Float64
+  beta::Tuple{Float64, Float64}
+  Rule(eta = 0.1, beta = (0.7, 0.8)) = eta < 0 ? error() : new(eta, beta)
+end
+```
+Any field called `eta` is assumed to be a learning rate, and cannot be negative.
+"""
+macro def(expr)
+  Meta.isexpr(expr, :struct) || throw("@def must act on a struct definition")
+  lines = expr.args[3].args
+  names, vals = [], []
+  for i in eachindex(lines)
+    lines[i] isa Symbol && throw("@def requires a default for every field")
+    Meta.isexpr(lines[i], :(=)) || continue
+    name, val = lines[i].args
+    push!(names, name)
+    push!(vals, val)
+    lines[i] = :($name::$typeof($val))
+  end
+  rule = Meta.isexpr(expr.args[2], :<:) ? expr.args[2].args[1] : expr.args[2]
+  check = :eta in names ? :(eta < 0 && throw(DomainError(eta, "the learning rate cannot be negative"))) : nothing
+  inner = :(function $rule($([Expr(:kw, nv...) for nv in zip(names,vals)]...))
+    $check
+    new($(names...))
+  end)
+  push!(lines, inner)
+  esc(expr)
+end
+