From bd482b12dc94463288f0cd7655cb9ce3e82c14e7 Mon Sep 17 00:00:00 2001
From: Harrison Grodin <harrison.grodin@gmail.com>
Date: Wed, 13 Feb 2019 21:13:06 -0500
Subject: [PATCH 1/5] Use `isequal` instead of `==`

---
 src/differentials.jl                         |  2 +-
 src/equations.jl                             |  4 +-
 src/function_registration.jl                 |  8 ++-
 src/operations.jl                            | 14 ++---
 src/simplify.jl                              |  2 +-
 src/systems/diffeqs/diffeqsystem.jl          |  4 +-
 src/systems/diffeqs/first_order_transform.jl |  2 +-
 src/utils.jl                                 |  2 +-
 src/variables.jl                             | 16 +++---
 test/derivatives.jl                          | 54 ++++++++++----------
 test/simplify.jl                             |  8 +--
 test/system_construction.jl                  | 20 ++++----
 test/variable_parsing.jl                     | 12 +++--
 13 files changed, 78 insertions(+), 70 deletions(-)

diff --git a/src/differentials.jl b/src/differentials.jl
index 08bd80de3d..ed87dcdfde 100644
--- a/src/differentials.jl
+++ b/src/differentials.jl
@@ -12,7 +12,7 @@ function (D::Differential)(x::Variable)
     return Operation(D, Expression[x])
 end
 (::Differential)(::Any) = Constant(0)
-Base.:(==)(D1::Differential, D2::Differential) = D1.x == D2.x
+Base.:(==)(D1::Differential, D2::Differential) = isequal(D1.x, D2.x)
 
 function expand_derivatives(O::Operation)
     @. O.args = expand_derivatives(O.args)
diff --git a/src/equations.jl b/src/equations.jl
index e721eb70f9..a914b81142 100644
--- a/src/equations.jl
+++ b/src/equations.jl
@@ -5,7 +5,7 @@ struct Equation
     lhs::Expression
     rhs::Expression
 end
-Base.:(==)(a::Equation, b::Equation) = (a.lhs, a.rhs) == (b.lhs, b.rhs)
+Base.:(==)(a::Equation, b::Equation) = isequal((a.lhs, a.rhs), (b.lhs, b.rhs))
 
 Base.:~(lhs::Expression, rhs::Expression) = Equation(lhs, rhs)
 Base.:~(lhs::Expression, rhs::Number    ) = Equation(lhs, rhs)
@@ -13,7 +13,7 @@ Base.:~(lhs::Number    , rhs::Expression) = Equation(lhs, rhs)
 
 
 _is_dependent(x::Variable) = !x.known && !isempty(x.dependents)
-_is_parameter(iv) = x -> x.known && x ≠ iv
+_is_parameter(iv) = x -> x.known && !isequal(x, iv)
 _is_known(x::Variable) = x.known
 _is_unknown(x::Variable) = !x.known
 
diff --git a/src/function_registration.jl b/src/function_registration.jl
index cc72ba685f..61a2e8a15a 100644
--- a/src/function_registration.jl
+++ b/src/function_registration.jl
@@ -32,7 +32,13 @@ for (M, f, arity) in DiffRules.diffrules()
     @eval @register $sig
 end
 
-for fun = (:<, :>, :(==), :!, :&, :|, :div)
+for fun ∈ [:!]
+    basefun = Expr(:., Base, QuoteNode(fun))
+    sig = :($basefun(x))
+    @eval @register $sig
+end
+
+for fun ∈ [:<, :>, :(==), :&, :|, :div]
     basefun = Expr(:., Base, QuoteNode(fun))
     sig = :($basefun(x,y))
     @eval @register $sig
diff --git a/src/operations.jl b/src/operations.jl
index f024b848e3..03c794f16e 100644
--- a/src/operations.jl
+++ b/src/operations.jl
@@ -4,15 +4,15 @@ struct Operation <: Expression
 end
 
 # Recursive ==
-function Base.:(==)(x::Operation,y::Operation)
+function Base.isequal(x::Operation,y::Operation)
     x.op == y.op && length(x.args) == length(y.args) && all(isequal.(x.args,y.args))
 end
-Base.:(==)(::Operation, ::Number   ) = false
-Base.:(==)(::Number   , ::Operation) = false
-Base.:(==)(::Operation, ::Variable ) = false
-Base.:(==)(::Variable , ::Operation) = false
-Base.:(==)(::Operation, ::Constant ) = false
-Base.:(==)(::Constant , ::Operation) = false
+Base.isequal(::Operation, ::Number   ) = false
+Base.isequal(::Number   , ::Operation) = false
+Base.isequal(::Operation, ::Variable ) = false
+Base.isequal(::Variable , ::Operation) = false
+Base.isequal(::Operation, ::Constant ) = false
+Base.isequal(::Constant , ::Operation) = false
 
 Base.convert(::Type{Expr}, O::Operation) =
     build_expr(:call, Any[Symbol(O.op); convert.(Expr, O.args)])
diff --git a/src/simplify.jl b/src/simplify.jl
index 0c897face3..d5a57529c4 100644
--- a/src/simplify.jl
+++ b/src/simplify.jl
@@ -4,7 +4,7 @@ function simplify_constants(O::Operation, shorten_tree)
         if is_operation(O′)
             O′ = Operation(O′.op, simplify_constants.(O′.args, shorten_tree))
         end
-        O == O′ && return O
+        isequal(O, O′) && return O
         O = O′
     end
 end
diff --git a/src/systems/diffeqs/diffeqsystem.jl b/src/systems/diffeqs/diffeqsystem.jl
index ad1e35393c..ad5ea1537b 100644
--- a/src/systems/diffeqs/diffeqsystem.jl
+++ b/src/systems/diffeqs/diffeqsystem.jl
@@ -10,7 +10,7 @@ function flatten_differential(O::Operation)
     @assert is_derivative(O) "invalid differential: $O"
     is_derivative(O.args[1]) || return (O.args[1], O.op.x, 1)
     (x, t, order) = flatten_differential(O.args[1])
-    t == O.op.x || throw(ArgumentError("non-matching differentials on lhs: $t, $(O.op.x)"))
+    isequal(t, O.op.x) || throw(ArgumentError("non-matching differentials on lhs: $t, $(O.op.x)"))
     return (x, t, order + 1)
 end
 
@@ -26,7 +26,7 @@ function Base.convert(::Type{DiffEq}, eq::Equation)
     (x, t, n) = flatten_differential(eq.lhs)
     return DiffEq(x, t, n, eq.rhs)
 end
-Base.:(==)(a::DiffEq, b::DiffEq) = (a.x, a.t, a.n, a.rhs) == (b.x, b.t, b.n, b.rhs)
+Base.:(==)(a::DiffEq, b::DiffEq) = isequal((a.x, a.t, a.n, a.rhs), (b.x, b.t, b.n, b.rhs))
 get_args(eq::DiffEq) = Expression[eq.x, eq.t, eq.rhs]
 
 struct DiffEqSystem <: AbstractSystem
diff --git a/src/systems/diffeqs/first_order_transform.jl b/src/systems/diffeqs/first_order_transform.jl
index 706de49f9a..7fecf3c318 100644
--- a/src/systems/diffeqs/first_order_transform.jl
+++ b/src/systems/diffeqs/first_order_transform.jl
@@ -17,7 +17,7 @@ function ode_order_lowering(eqs, iv)
         var, maxorder = eq.x, eq.n
         if maxorder > get(var_order, var, 0)
             var_order[var] = maxorder
-            var ∈ vars || push!(vars, var)
+            any(isequal(var), vars) || push!(vars, var)
         end
         var′ = lower_varname(eq.x, eq.t, eq.n - 1)
         rhs′ = rename(eq.rhs)
diff --git a/src/utils.jl b/src/utils.jl
index f5e83aeae3..e8753f7500 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -65,4 +65,4 @@ is_derivative(::Any) = false
 
 has_dependent(t::Variable) = Base.Fix2(has_dependent, t)
 has_dependent(x::Variable, t::Variable) =
-    t ∈ x.dependents || any(has_dependent(t), x.dependents)
+    any(isequal(t), x.dependents) || any(has_dependent(t), x.dependents)
diff --git a/src/variables.jl b/src/variables.jl
index 32f4a9ff79..b5c5faf3a7 100644
--- a/src/variables.jl
+++ b/src/variables.jl
@@ -22,14 +22,14 @@ Base.isone(ex::Expression)  = isa(ex, Constant) && isone(ex.value)
 
 
 # Variables use isequal for equality since == is an Operation
-Base.:(==)(x::Variable, y::Variable) = (x.name, x.known) == (y.name, y.known)
-Base.:(==)(::Variable, ::Number) = false
-Base.:(==)(::Number, ::Variable) = false
-Base.:(==)(::Variable, ::Constant) = false
-Base.:(==)(::Constant, ::Variable) = false
-Base.:(==)(c::Constant, n::Number) = c.value == n
-Base.:(==)(n::Number, c::Constant) = c.value == n
-Base.:(==)(a::Constant, b::Constant) = a.value == b.value
+Base.isequal(x::Variable, y::Variable) = (x.name, x.known) == (y.name, y.known)
+Base.isequal(::Variable, ::Number) = false
+Base.isequal(::Number, ::Variable) = false
+Base.isequal(::Variable, ::Constant) = false
+Base.isequal(::Constant, ::Variable) = false
+Base.isequal(c::Constant, n::Number) = c.value == n
+Base.isequal(n::Number, c::Constant) = c.value == n
+Base.isequal(a::Constant, b::Constant) = a.value == b.value
 
 function Base.convert(::Type{Expr}, x::Variable)
     x.known               || return x.name
diff --git a/test/derivatives.jl b/test/derivatives.jl
index 768fd80b14..cee1fdc0aa 100644
--- a/test/derivatives.jl
+++ b/test/derivatives.jl
@@ -6,52 +6,52 @@ using Test
 @Unknown x(t) y(t) z(t)
 @Deriv D'~t D2''~t
 
-@test expand_derivatives(D(t)) == 1
-@test expand_derivatives(D(D(t))) == 0
+@test isequal(expand_derivatives(D(t)), 1)
+@test isequal(expand_derivatives(D(D(t))), 0)
 
 dsin = D(sin(t))
-@test expand_derivatives(dsin) == cos(t)
+@test isequal(expand_derivatives(dsin), cos(t))
 
 dcsch = D(csch(t))
-@test expand_derivatives(dcsch) == simplify_constants(coth(t) * csch(t) * -1)
+@test isequal(expand_derivatives(dcsch), simplify_constants(coth(t) * csch(t) * -1))
 
-@test expand_derivatives(D(-7)) == 0
-@test expand_derivatives(D(sin(2t))) == simplify_constants(cos(2t) * 2)
-@test expand_derivatives(D2(sin(t))) == simplify_constants(-sin(t))
-@test expand_derivatives(D2(sin(2t))) == simplify_constants(sin(2t) * -4)
-@test expand_derivatives(D2(t)) == 0
-@test expand_derivatives(D2(5)) == 0
+@test isequal(expand_derivatives(D(-7)), 0)
+@test isequal(expand_derivatives(D(sin(2t))), simplify_constants(cos(2t) * 2))
+@test isequal(expand_derivatives(D2(sin(t))), simplify_constants(-sin(t)))
+@test isequal(expand_derivatives(D2(sin(2t))), simplify_constants(sin(2t) * -4))
+@test isequal(expand_derivatives(D2(t)), 0)
+@test isequal(expand_derivatives(D2(5)), 0)
 
 # Chain rule
 dsinsin = D(sin(sin(t)))
-@test expand_derivatives(dsinsin) == cos(sin(t))*cos(t)
+@test isequal(expand_derivatives(dsinsin), cos(sin(t))*cos(t))
 
 d1 = D(sin(t)*t)
 d2 = D(sin(t)*cos(t))
-@test expand_derivatives(d1) == t*cos(t)+sin(t)
-@test expand_derivatives(d2) == simplify_constants(cos(t)*cos(t)+sin(t)*(-1*sin(t)))
+@test isequal(expand_derivatives(d1), t*cos(t)+sin(t))
+@test isequal(expand_derivatives(d2), simplify_constants(cos(t)*cos(t)+sin(t)*(-1*sin(t))))
 
 eqs = [0 ~ σ*(y-x),
        0 ~ x*(ρ-z)-y,
        0 ~ x*y - β*z]
 sys = NonlinearSystem(eqs,[x,y,z],[σ,ρ,β])
 jac = calculate_jacobian(sys)
-@test jac[1,1] == σ*-1
-@test jac[1,2] == σ
-@test jac[1,3] == 0
-@test jac[2,1] == ρ-z
-@test jac[2,2] == -1
-@test jac[2,3] == x*-1
-@test jac[3,1] == y
-@test jac[3,2] == x
-@test jac[3,3] == -1*β
+@test isequal(jac[1,1], σ*-1)
+@test isequal(jac[1,2], σ)
+@test isequal(jac[1,3], 0)
+@test isequal(jac[2,1], ρ-z)
+@test isequal(jac[2,2], -1)
+@test isequal(jac[2,3], x*-1)
+@test isequal(jac[3,1], y)
+@test isequal(jac[3,2], x)
+@test isequal(jac[3,3], -1*β)
 
 # Variable dependence checking in differentiation
 @Unknown a(t) b(a)
-@test D(b) ≠ 0
+@test !isequal(D(b), 0)
 
-@test expand_derivatives(D(x * y)) == simplify_constants(y*D(x) + x*D(y))
-@test_broken expand_derivatives(D(x * y)) == simplify_constants(D(x)*y + x*D(y))
+@test isequal(expand_derivatives(D(x * y)), simplify_constants(y*D(x) + x*D(y)))
+@test_broken isequal(expand_derivatives(D(x * y)), simplify_constants(D(x)*y + x*D(y)))
 
-@test expand_derivatives(D(2t)) == 2
-@test expand_derivatives(D(2x)) == 2D(x)
+@test isequal(expand_derivatives(D(2t)), 2)
+@test isequal(expand_derivatives(D(2x)), 2D(x))
diff --git a/test/simplify.jl b/test/simplify.jl
index 0e2f876bc5..7daae19fed 100644
--- a/test/simplify.jl
+++ b/test/simplify.jl
@@ -5,14 +5,14 @@ using Test
 @Unknown x(t) y(t) z(t)
 
 null_op = 0*t
-@test simplify_constants(null_op) == 0
+@test isequal(simplify_constants(null_op), 0)
 
 one_op = 1*t
-@test simplify_constants(one_op) == t
+@test isequal(simplify_constants(one_op), t)
 
 identity_op = Operation(identity,[x])
-@test simplify_constants(identity_op) == x
+@test isequal(simplify_constants(identity_op), x)
 
 minus_op = -x
-@test simplify_constants(minus_op) == -1*x
+@test isequal(simplify_constants(minus_op), -1*x)
 simplify_constants(minus_op)
diff --git a/test/system_construction.jl b/test/system_construction.jl
index 7fa89c2a08..7211164b6c 100644
--- a/test/system_construction.jl
+++ b/test/system_construction.jl
@@ -22,7 +22,7 @@ ModelingToolkit.generate_ode_iW(de)
 de2 = DiffEqSystem(eqs, t)
 
 function test_vars_extraction(de, de2)
-    @test de.iv == de2.iv
+    @test isequal(de.iv, de2.iv)
     for el in (:dvs, :ps)
         names2 = sort(collect(var.name for var in getfield(de2,el)))
         names = sort(collect(var.name for var in getfield(de,el)))
@@ -110,15 +110,15 @@ eqs = [0 ~ σ*(y-x),
 ns = NonlinearSystem(eqs, [x,y,z], [σ,ρ,β])
 jac = calculate_jacobian(ns)
 @testset "nlsys jacobian" begin
-    @test jac[1,1] == σ * -1
-    @test jac[1,2] == σ
-    @test jac[1,3] == 0
-    @test jac[2,1] == ρ - z
-    @test jac[2,2] == -1
-    @test jac[2,3] == x * -1
-    @test jac[3,1] == y
-    @test jac[3,2] == x
-    @test jac[3,3] == -1 * β
+    @test isequal(jac[1,1], σ * -1)
+    @test isequal(jac[1,2], σ)
+    @test isequal(jac[1,3], 0)
+    @test isequal(jac[2,1], ρ - z)
+    @test isequal(jac[2,2], -1)
+    @test isequal(jac[2,3], x * -1)
+    @test isequal(jac[3,1], y)
+    @test isequal(jac[3,2], x)
+    @test isequal(jac[3,3], -1 * β)
 end
 nlsys_func = generate_function(ns)
 jac_func = generate_jacobian(ns)
diff --git a/test/variable_parsing.jl b/test/variable_parsing.jl
index 96ba18aecd..df27994b7d 100644
--- a/test/variable_parsing.jl
+++ b/test/variable_parsing.jl
@@ -8,9 +8,9 @@ using Test
 x1 = Unknown(:x, [t])
 y1 = Unknown(:y, [t])
 z1 = Unknown(:z, [t])
-@test x1 == x
-@test y1 == y
-@test z1 == z
+@test isequal(x1, x)
+@test isequal(y1, y)
+@test isequal(z1, z)
 @test convert(Expr, x) == :x
 @test convert(Expr, y) == :y
 @test convert(Expr, z) == :z
@@ -21,8 +21,8 @@ z1 = Unknown(:z, [t])
 end
 t1 = Parameter(:t)
 s1 = Parameter(:s)
-@test t1 == t
-@test s1 == s
+@test isequal(t1, t)
+@test isequal(s1, s)
 @test convert(Expr, t) == :t
 @test convert(Expr, s) == :s
 @test convert(Expr, cos(t + sin(s))) == :(cos(t + sin(s)))
@@ -31,3 +31,5 @@ s1 = Parameter(:s)
 D1 = Differential(t)
 @test D1 == D
 @test convert(Expr, D) == D
+
+@test isequal(x ≤ y + 1, (x < y + 1) | (x == y + 1))

From e42a074bd32630e63f6983614195965b9f7a5d91 Mon Sep 17 00:00:00 2001
From: Harrison Grodin <harrison.grodin@gmail.com>
Date: Wed, 13 Feb 2019 21:51:42 -0500
Subject: [PATCH 2/5] Replace @Unknown with @Variable, remove Parameter

---
 README.md                           | 28 ++++++++++++++--------------
 src/systems/diffeqs/diffeqsystem.jl |  2 +-
 src/variables.jl                    | 19 +++++++++----------
 test/derivatives.jl                 |  4 ++--
 test/simplify.jl                    |  2 +-
 test/system_construction.jl         |  6 +++---
 test/variable_parsing.jl            | 16 ++++++++--------
 7 files changed, 38 insertions(+), 39 deletions(-)

diff --git a/README.md b/README.md
index 2073663147..0b6cdc8c31 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ to manipulate.
 ### Example: ODE
 
 Let's build an ODE. First we define some variables. In a differential equation
-system, we need to differentiate between our unknown (dependent) variables
+system, we need to differentiate between our (dependent) variables
 and parameters. Therefore we label them as follows:
 
 ```julia
@@ -29,7 +29,7 @@ using ModelingToolkit
 
 # Define some variables
 @Param t σ ρ β
-@Unknown x(t) y(t) z(t)
+@Variable x(t) y(t) z(t)
 @Deriv D'~t
 ```
 
@@ -78,10 +78,10 @@ f = ODEFunction(de)
 
 We can also build nonlinear systems. Let's say we wanted to solve for the steady
 state of the previous ODE. This is the nonlinear system defined by where the
-derivatives are zero. We use unknown variables for our nonlinear system.
+derivatives are zero. We use (unknown) variables for our nonlinear system.
 
 ```julia
-@Unknown x y z
+@Variable x y z
 @Param σ ρ β
 
 # Define a nonlinear system
@@ -173,7 +173,7 @@ structure is as follows:
   the system of equations.
 - Name to subtype mappings: these describe how variable `subtype`s are mapped
   to the contexts of the system. For example, for a differential equation,
-  the unknown variable corresponds to given subtypes and then the `eqs` can
+  the variable corresponds to given subtypes and then the `eqs` can
   be analyzed knowing what the state variables are.
 - Variable names which do not fall into one of the system's core subtypes are
   treated as intermediates which can be used for holding subcalculations and
@@ -244,21 +244,21 @@ syntactic sugar in some form. For example, the variable construction:
 
 ```julia
 @Param t σ ρ β
-@Unknown x(t) y(t) z(t)
+@Variable x(t) y(t) z(t)
 @Deriv D'~t
 ```
 
 is syntactic sugar for:
 
 ```julia
-t = Parameter(:t)
-x = Unknown(:x, [t])
-y = Unknown(:y, [t])
-z = Unknown(:z, [t])
+t = Variable(:t; known = true)
+x = Variable(:x, [t])
+y = Variable(:y, [t])
+z = Variable(:z, [t])
 D = Differential(t)
-σ = Parameter(:σ)
-ρ = Parameter(:ρ)
-β = Parameter(:β)
+σ = Variable(:σ; known = true)
+ρ = Variable(:ρ; known = true)
+β = Variable(:β; known = true)
 ```
 
 ### Intermediate Calculations
@@ -266,7 +266,7 @@ D = Differential(t)
 The system building functions can handle intermediate calculations. For example,
 
 ```julia
-@Unknown x y z
+@Variable x y z
 @Param σ ρ β
 a = y - x
 eqs = [0 ~ σ*a,
diff --git a/src/systems/diffeqs/diffeqsystem.jl b/src/systems/diffeqs/diffeqsystem.jl
index ad5ea1537b..24204c4832 100644
--- a/src/systems/diffeqs/diffeqsystem.jl
+++ b/src/systems/diffeqs/diffeqsystem.jl
@@ -79,7 +79,7 @@ end
 function generate_ode_iW(sys::DiffEqSystem, simplify=true; version::FunctionVersion = ArrayFunction)
     jac = calculate_jacobian(sys)
 
-    gam = Parameter(:gam)
+    gam = Variable(:gam; known = true)
 
     W = LinearAlgebra.I - gam*jac
     W = SMatrix{size(W,1),size(W,2)}(W)
diff --git a/src/variables.jl b/src/variables.jl
index b5c5faf3a7..60cb708cd5 100644
--- a/src/variables.jl
+++ b/src/variables.jl
@@ -1,15 +1,14 @@
-export Variable, Unknown, Parameter, @Unknown, @Param
+export Variable, @Variable, @Param
 
 
 struct Variable <: Expression
     name::Symbol
-    known::Bool
     dependents::Vector{Variable}
+    known::Bool
+    Variable(name, dependents = Variable[]; known = false) =
+        new(name, dependents, known)
 end
 
-Parameter(name, dependents = Variable[]) = Variable(name, true, dependents)
-Unknown(name, dependents = Variable[]) = Variable(name, false, dependents)
-
 
 struct Constant <: Expression
     value::Number
@@ -41,7 +40,7 @@ Base.convert(::Type{Expr}, c::Constant) = c.value
 Base.show(io::IO, x::Variable) = print(io, x.name)
 
 # Build variables more easily
-function _parse_vars(macroname, fun, x)
+function _parse_vars(macroname, known, x)
     ex = Expr(:block)
     var_names = Symbol[]
     # if parsing things in the form of
@@ -65,15 +64,15 @@ function _parse_vars(macroname, fun, x)
         end
 
         push!(var_names, var_name)
-        expr = :($var_name = $fun($(Meta.quot(var_name)), $dependents))
+        expr = :($var_name = $Variable($(Meta.quot(var_name)), $dependents; known = $known))
         push!(ex.args, expr)
     end
     push!(ex.args, build_expr(:tuple, var_names))
     return ex
 end
-macro Unknown(xs...)
-    esc(_parse_vars(:Unknown, Unknown, xs))
+macro Variable(xs...)
+    esc(_parse_vars(:Variable, false, xs))
 end
 macro Param(xs...)
-    esc(_parse_vars(:Param, Parameter, xs))
+    esc(_parse_vars(:Param, true, xs))
 end
diff --git a/test/derivatives.jl b/test/derivatives.jl
index cee1fdc0aa..8337efaa53 100644
--- a/test/derivatives.jl
+++ b/test/derivatives.jl
@@ -3,7 +3,7 @@ using Test
 
 # Derivatives
 @Param t σ ρ β
-@Unknown x(t) y(t) z(t)
+@Variable x(t) y(t) z(t)
 @Deriv D'~t D2''~t
 
 @test isequal(expand_derivatives(D(t)), 1)
@@ -47,7 +47,7 @@ jac = calculate_jacobian(sys)
 @test isequal(jac[3,3], -1*β)
 
 # Variable dependence checking in differentiation
-@Unknown a(t) b(a)
+@Variable a(t) b(a)
 @test !isequal(D(b), 0)
 
 @test isequal(expand_derivatives(D(x * y)), simplify_constants(y*D(x) + x*D(y)))
diff --git a/test/simplify.jl b/test/simplify.jl
index 7daae19fed..6bd97ea1b0 100644
--- a/test/simplify.jl
+++ b/test/simplify.jl
@@ -2,7 +2,7 @@ using ModelingToolkit
 using Test
 
 @Param t
-@Unknown x(t) y(t) z(t)
+@Variable x(t) y(t) z(t)
 
 null_op = 0*t
 @test isequal(simplify_constants(null_op), 0)
diff --git a/test/system_construction.jl b/test/system_construction.jl
index 7211164b6c..19e13a73c0 100644
--- a/test/system_construction.jl
+++ b/test/system_construction.jl
@@ -3,7 +3,7 @@ using Test
 
 # Define some variables
 @Param t σ ρ β
-@Unknown x(t) y(t) z(t)
+@Variable x(t) y(t) z(t)
 @Deriv D'~t
 
 # Define a differential equation
@@ -48,7 +48,7 @@ end
 # Conversion to first-order ODEs #17
 @Deriv D3'''~t
 @Deriv D2''~t
-@Unknown u(t) u_tt(t) u_t(t) x_t(t)
+@Variable u(t) u_tt(t) u_t(t) x_t(t)
 eqs = [D3(u) ~ 2(D2(u)) + D(u) + D(x) + 1
        D2(x) ~ D(x) + 2]
 de = DiffEqSystem(eqs, t)
@@ -100,7 +100,7 @@ test_vars_extraction(de, DiffEqSystem(eqs))
 end
 
 # Now nonlinear system with only variables
-@Unknown x y z
+@Variable x y z
 @Param σ ρ β
 
 # Define a nonlinear system
diff --git a/test/variable_parsing.jl b/test/variable_parsing.jl
index df27994b7d..a5c4488cb5 100644
--- a/test/variable_parsing.jl
+++ b/test/variable_parsing.jl
@@ -2,12 +2,12 @@ using ModelingToolkit
 using Test
 
 @Param t
-@Unknown x(t)
-@Unknown y(t)
-@Unknown z(t)
-x1 = Unknown(:x, [t])
-y1 = Unknown(:y, [t])
-z1 = Unknown(:z, [t])
+@Variable x(t)
+@Variable y(t)
+@Variable z(t)
+x1 = Variable(:x, [t])
+y1 = Variable(:y, [t])
+z1 = Variable(:z, [t])
 @test isequal(x1, x)
 @test isequal(y1, y)
 @test isequal(z1, z)
@@ -19,8 +19,8 @@ z1 = Unknown(:z, [t])
     t
     s
 end
-t1 = Parameter(:t)
-s1 = Parameter(:s)
+t1 = Variable(:t; known = true)
+s1 = Variable(:s; known = true)
 @test isequal(t1, t)
 @test isequal(s1, s)
 @test convert(Expr, t) == :t

From 1d92c523dc2267c8c45b80724f6a105f613ea06b Mon Sep 17 00:00:00 2001
From: Harrison Grodin <harrison.grodin@gmail.com>
Date: Wed, 13 Feb 2019 21:59:49 -0500
Subject: [PATCH 3/5] Remove unnecessary capitalization

Fixes #100.
---
 README.md                                    | 24 ++++++++++----------
 src/differentials.jl                         | 12 +++++-----
 src/systems/diffeqs/first_order_transform.jl |  2 +-
 src/variables.jl                             |  6 ++---
 test/derivatives.jl                          |  8 +++----
 test/simplify.jl                             |  4 ++--
 test/system_construction.jl                  | 22 +++++++++---------
 test/variable_parsing.jl                     | 12 +++++-----
 8 files changed, 45 insertions(+), 45 deletions(-)

diff --git a/README.md b/README.md
index 0b6cdc8c31..ba50af4f20 100644
--- a/README.md
+++ b/README.md
@@ -28,9 +28,9 @@ and parameters. Therefore we label them as follows:
 using ModelingToolkit
 
 # Define some variables
-@Param t σ ρ β
-@Variable x(t) y(t) z(t)
-@Deriv D'~t
+@param t σ ρ β
+@variable x(t) y(t) z(t)
+@deriv D'~t
 ```
 
 Then we build the system:
@@ -81,8 +81,8 @@ state of the previous ODE. This is the nonlinear system defined by where the
 derivatives are zero. We use (unknown) variables for our nonlinear system.
 
 ```julia
-@Variable x y z
-@Param σ ρ β
+@variable x y z
+@param σ ρ β
 
 # Define a nonlinear system
 eqs = [0 ~ σ*(y-x),
@@ -223,7 +223,7 @@ function via the dispatch:
 
 ```julia
 # `N` arguments are accepted by the relevant method of `my_function`
-ModelingToolkit.Derivative(::typeof(my_function), args::NTuple{N,Any}, ::Val{i})
+ModelingToolkit.derivative(::typeof(my_function), args::NTuple{N,Any}, ::Val{i})
 ```
 
 where `i` means that it's the derivative of the `i`th argument. `args` is the
@@ -233,7 +233,7 @@ You should return an `Operation` for the derivative of your function.
 For example, `sin(t)`'s derivative (by `t`) is given by the following:
 
 ```julia
-ModelingToolkit.Derivative(::typeof(sin), args::NTuple{1,Any}, ::Val{1}) = cos(args[1])
+ModelingToolkit.derivative(::typeof(sin), args::NTuple{1,Any}, ::Val{1}) = cos(args[1])
 ```
 
 ### Macro-free Usage
@@ -243,9 +243,9 @@ is accessible via a function-based interface. This means that all macros are
 syntactic sugar in some form. For example, the variable construction:
 
 ```julia
-@Param t σ ρ β
-@Variable x(t) y(t) z(t)
-@Deriv D'~t
+@param t σ ρ β
+@variable x(t) y(t) z(t)
+@deriv D'~t
 ```
 
 is syntactic sugar for:
@@ -266,8 +266,8 @@ D = Differential(t)
 The system building functions can handle intermediate calculations. For example,
 
 ```julia
-@Variable x y z
-@Param σ ρ β
+@variable x y z
+@param σ ρ β
 a = y - x
 eqs = [0 ~ σ*a,
        0 ~ x*(ρ-z)-y,
diff --git a/src/differentials.jl b/src/differentials.jl
index ed87dcdfde..2466ff8891 100644
--- a/src/differentials.jl
+++ b/src/differentials.jl
@@ -21,7 +21,7 @@ function expand_derivatives(O::Operation)
         D = O.op
         o = O.args[1]
         isa(o, Operation) || return O
-        return simplify_constants(sum(i->Derivative(o,i)*expand_derivatives(D(o.args[i])),1:length(o.args)))
+        return simplify_constants(sum(i->derivative(o,i)*expand_derivatives(D(o.args[i])),1:length(o.args)))
     end
 
     return O
@@ -29,13 +29,13 @@ end
 expand_derivatives(x) = x
 
 # Don't specialize on the function here
-Derivative(O::Operation, idx) = Derivative(O.op, (O.args...,), Val(idx))
+derivative(O::Operation, idx) = derivative(O.op, (O.args...,), Val(idx))
 
 # Pre-defined derivatives
 import DiffRules, SpecialFunctions, NaNMath
 for (modu, fun, arity) ∈ DiffRules.diffrules()
     for i ∈ 1:arity
-        @eval function Derivative(::typeof($modu.$fun), args::NTuple{$arity,Any}, ::Val{$i})
+        @eval function derivative(::typeof($modu.$fun), args::NTuple{$arity,Any}, ::Val{$i})
             M, f = $(modu, fun)
             partials = DiffRules.diffrule(M, f, args...)
             dx = @static $arity == 1 ? partials : partials[$i]
@@ -60,7 +60,7 @@ function _differential_macro(x)
     lhss = Symbol[]
     x = flatten_expr!(x)
     for di in x
-        @assert di isa Expr && di.args[1] == :~ "@Deriv expects a form that looks like `@Deriv D''~t E'~t`"
+        @assert di isa Expr && di.args[1] == :~ "@deriv expects a form that looks like `@deriv D''~t E'~t`"
         lhs = di.args[2]
         rhs = di.args[3]
         order, lhs = count_order(lhs)
@@ -72,7 +72,7 @@ function _differential_macro(x)
     ex
 end
 
-macro Deriv(x...)
+macro deriv(x...)
     esc(_differential_macro(x))
 end
 
@@ -80,4 +80,4 @@ function calculate_jacobian(eqs,vars)
     Expression[Differential(vars[j])(eqs[i]) for i in 1:length(eqs), j in 1:length(vars)]
 end
 
-export Differential, expand_derivatives, @Deriv, calculate_jacobian
+export Differential, expand_derivatives, @deriv, calculate_jacobian
diff --git a/src/systems/diffeqs/first_order_transform.jl b/src/systems/diffeqs/first_order_transform.jl
index 7fecf3c318..40dbda0f7d 100644
--- a/src/systems/diffeqs/first_order_transform.jl
+++ b/src/systems/diffeqs/first_order_transform.jl
@@ -1,7 +1,7 @@
 function lower_varname(var::Variable, idv, order)
     order == 0 && return var
     name = Symbol(var.name, :_, string(idv.name)^order)
-    return Variable(name, var.known, var.dependents)
+    return Variable(name, var.dependents; known = var.known)
 end
 
 function ode_order_lowering(sys::DiffEqSystem)
diff --git a/src/variables.jl b/src/variables.jl
index 60cb708cd5..88a3fb22ca 100644
--- a/src/variables.jl
+++ b/src/variables.jl
@@ -1,4 +1,4 @@
-export Variable, @Variable, @Param
+export Variable, @variable, @param
 
 
 struct Variable <: Expression
@@ -70,9 +70,9 @@ function _parse_vars(macroname, known, x)
     push!(ex.args, build_expr(:tuple, var_names))
     return ex
 end
-macro Variable(xs...)
+macro variable(xs...)
     esc(_parse_vars(:Variable, false, xs))
 end
-macro Param(xs...)
+macro param(xs...)
     esc(_parse_vars(:Param, true, xs))
 end
diff --git a/test/derivatives.jl b/test/derivatives.jl
index 8337efaa53..e6bf9e0065 100644
--- a/test/derivatives.jl
+++ b/test/derivatives.jl
@@ -2,9 +2,9 @@ using ModelingToolkit
 using Test
 
 # Derivatives
-@Param t σ ρ β
-@Variable x(t) y(t) z(t)
-@Deriv D'~t D2''~t
+@param t σ ρ β
+@variable x(t) y(t) z(t)
+@deriv D'~t D2''~t
 
 @test isequal(expand_derivatives(D(t)), 1)
 @test isequal(expand_derivatives(D(D(t))), 0)
@@ -47,7 +47,7 @@ jac = calculate_jacobian(sys)
 @test isequal(jac[3,3], -1*β)
 
 # Variable dependence checking in differentiation
-@Variable a(t) b(a)
+@variable a(t) b(a)
 @test !isequal(D(b), 0)
 
 @test isequal(expand_derivatives(D(x * y)), simplify_constants(y*D(x) + x*D(y)))
diff --git a/test/simplify.jl b/test/simplify.jl
index 6bd97ea1b0..6853ec6e8e 100644
--- a/test/simplify.jl
+++ b/test/simplify.jl
@@ -1,8 +1,8 @@
 using ModelingToolkit
 using Test
 
-@Param t
-@Variable x(t) y(t) z(t)
+@param t
+@variable x(t) y(t) z(t)
 
 null_op = 0*t
 @test isequal(simplify_constants(null_op), 0)
diff --git a/test/system_construction.jl b/test/system_construction.jl
index 19e13a73c0..876b265ffc 100644
--- a/test/system_construction.jl
+++ b/test/system_construction.jl
@@ -2,9 +2,9 @@ using ModelingToolkit
 using Test
 
 # Define some variables
-@Param t σ ρ β
-@Variable x(t) y(t) z(t)
-@Deriv D'~t
+@param t σ ρ β
+@variable x(t) y(t) z(t)
+@deriv D'~t
 
 # Define a differential equation
 eqs = [D(x) ~ σ*(y-x),
@@ -32,7 +32,7 @@ end
 test_vars_extraction(de, de2)
 
 @testset "time-varying parameters" begin
-    @Param σ′(t)
+    @param σ′(t)
     eqs = [D(x) ~ σ′*(y-x),
            D(y) ~ x*(ρ-z)-y,
            D(z) ~ x*y - β*z]
@@ -46,9 +46,9 @@ test_vars_extraction(de, de2)
 end
 
 # Conversion to first-order ODEs #17
-@Deriv D3'''~t
-@Deriv D2''~t
-@Variable u(t) u_tt(t) u_t(t) x_t(t)
+@deriv D3'''~t
+@deriv D2''~t
+@variable u(t) u_tt(t) u_t(t) x_t(t)
 eqs = [D3(u) ~ 2(D2(u)) + D(u) + D(x) + 1
        D2(x) ~ D(x) + 2]
 de = DiffEqSystem(eqs, t)
@@ -84,8 +84,8 @@ end
 
 generate_function(ns)
 
-@Deriv D'~t
-@Param A B C
+@deriv D'~t
+@param A B C
 _x = y / C
 eqs = [D(x) ~ -A*x,
        D(y) ~ A*x - B*_x]
@@ -100,8 +100,8 @@ test_vars_extraction(de, DiffEqSystem(eqs))
 end
 
 # Now nonlinear system with only variables
-@Variable x y z
-@Param σ ρ β
+@variable x y z
+@param σ ρ β
 
 # Define a nonlinear system
 eqs = [0 ~ σ*(y-x),
diff --git a/test/variable_parsing.jl b/test/variable_parsing.jl
index a5c4488cb5..9a97f4da19 100644
--- a/test/variable_parsing.jl
+++ b/test/variable_parsing.jl
@@ -1,10 +1,10 @@
 using ModelingToolkit
 using Test
 
-@Param t
-@Variable x(t)
-@Variable y(t)
-@Variable z(t)
+@param t
+@variable x(t)
+@variable y(t)
+@variable z(t)
 x1 = Variable(:x, [t])
 y1 = Variable(:y, [t])
 z1 = Variable(:z, [t])
@@ -15,7 +15,7 @@ z1 = Variable(:z, [t])
 @test convert(Expr, y) == :y
 @test convert(Expr, z) == :z
 
-@Param begin
+@param begin
     t
     s
 end
@@ -27,7 +27,7 @@ s1 = Variable(:s; known = true)
 @test convert(Expr, s) == :s
 @test convert(Expr, cos(t + sin(s))) == :(cos(t + sin(s)))
 
-@Deriv D'~t
+@deriv D'~t
 D1 = Differential(t)
 @test D1 == D
 @test convert(Expr, D) == D

From 47b5b00b6b9e6836c6815f259686118ccda39222 Mon Sep 17 00:00:00 2001
From: Harrison Grodin <harrison.grodin@gmail.com>
Date: Wed, 13 Feb 2019 22:21:46 -0500
Subject: [PATCH 4/5] Clean up exports

---
 src/ModelingToolkit.jl                       | 10 +++++-----
 src/differentials.jl                         |  5 +++--
 src/simplify.jl                              |  5 +++--
 src/systems/diffeqs/first_order_transform.jl |  5 +++--
 4 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/ModelingToolkit.jl b/src/ModelingToolkit.jl
index 56693a3441..5ad35ad2ce 100644
--- a/src/ModelingToolkit.jl
+++ b/src/ModelingToolkit.jl
@@ -1,5 +1,10 @@
 module ModelingToolkit
 
+export Operation, Expression
+export calculate_jacobian, generate_jacobian, generate_function
+export @register
+
+
 using DiffEqBase
 using StaticArrays, LinearAlgebra
 
@@ -30,9 +35,4 @@ include("function_registration.jl")
 include("simplify.jl")
 include("utils.jl")
 
-export Operation, Expression, AbstractComponent
-export calculate_jacobian, generate_jacobian, generate_function
-export ArrayFunction, SArrayFunction
-export @register
-
 end # module
diff --git a/src/differentials.jl b/src/differentials.jl
index 2466ff8891..ae5c6b75d2 100644
--- a/src/differentials.jl
+++ b/src/differentials.jl
@@ -1,3 +1,6 @@
+export Differential, expand_derivatives, @deriv
+
+
 struct Differential <: Function
     x::Expression
 end
@@ -79,5 +82,3 @@ end
 function calculate_jacobian(eqs,vars)
     Expression[Differential(vars[j])(eqs[i]) for i in 1:length(eqs), j in 1:length(vars)]
 end
-
-export Differential, expand_derivatives, @deriv, calculate_jacobian
diff --git a/src/simplify.jl b/src/simplify.jl
index d5a57529c4..53206f0688 100644
--- a/src/simplify.jl
+++ b/src/simplify.jl
@@ -1,3 +1,6 @@
+export simplify_constants
+
+
 function simplify_constants(O::Operation, shorten_tree)
     while true
         O′ = _simplify_constants(O, shorten_tree)
@@ -72,5 +75,3 @@ function _simplify_constants(O::Operation, shorten_tree)
 end
 _simplify_constants(x, shorten_tree) = x
 _simplify_constants(x) = _simplify_constants(x, true)
-
-export simplify_constants
diff --git a/src/systems/diffeqs/first_order_transform.jl b/src/systems/diffeqs/first_order_transform.jl
index 40dbda0f7d..c0db1574cf 100644
--- a/src/systems/diffeqs/first_order_transform.jl
+++ b/src/systems/diffeqs/first_order_transform.jl
@@ -1,3 +1,6 @@
+export ode_order_lowering
+
+
 function lower_varname(var::Variable, idv, order)
     order == 0 && return var
     name = Symbol(var.name, :_, string(idv.name)^order)
@@ -45,5 +48,3 @@ function rename(O::Expression)
     end
     return Operation(O.op, rename.(O.args))
 end
-
-export ode_order_lowering

From 63794852be7ab9dd7ca5398b399c22a42f7311e7 Mon Sep 17 00:00:00 2001
From: Harrison Grodin <harrison.grodin@gmail.com>
Date: Thu, 7 Mar 2019 17:35:52 -0500
Subject: [PATCH 5/5] Make macro naming consistent

---
 README.md                   | 20 ++++++++++----------
 src/differentials.jl        |  6 +++---
 src/variables.jl            |  6 +++---
 test/derivatives.jl         |  8 ++++----
 test/simplify.jl            |  4 ++--
 test/system_construction.jl | 22 +++++++++++-----------
 test/variable_parsing.jl    | 12 ++++++------
 7 files changed, 39 insertions(+), 39 deletions(-)

diff --git a/README.md b/README.md
index ba50af4f20..0fcd128f7a 100644
--- a/README.md
+++ b/README.md
@@ -28,9 +28,9 @@ and parameters. Therefore we label them as follows:
 using ModelingToolkit
 
 # Define some variables
-@param t σ ρ β
-@variable x(t) y(t) z(t)
-@deriv D'~t
+@parameters t σ ρ β
+@variables x(t) y(t) z(t)
+@derivatives D'~t
 ```
 
 Then we build the system:
@@ -81,8 +81,8 @@ state of the previous ODE. This is the nonlinear system defined by where the
 derivatives are zero. We use (unknown) variables for our nonlinear system.
 
 ```julia
-@variable x y z
-@param σ ρ β
+@variables x y z
+@parameters σ ρ β
 
 # Define a nonlinear system
 eqs = [0 ~ σ*(y-x),
@@ -243,9 +243,9 @@ is accessible via a function-based interface. This means that all macros are
 syntactic sugar in some form. For example, the variable construction:
 
 ```julia
-@param t σ ρ β
-@variable x(t) y(t) z(t)
-@deriv D'~t
+@parameters t σ ρ β
+@variables x(t) y(t) z(t)
+@derivatives D'~t
 ```
 
 is syntactic sugar for:
@@ -266,8 +266,8 @@ D = Differential(t)
 The system building functions can handle intermediate calculations. For example,
 
 ```julia
-@variable x y z
-@param σ ρ β
+@variables x y z
+@parameters σ ρ β
 a = y - x
 eqs = [0 ~ σ*a,
        0 ~ x*(ρ-z)-y,
diff --git a/src/differentials.jl b/src/differentials.jl
index ae5c6b75d2..25a0498e76 100644
--- a/src/differentials.jl
+++ b/src/differentials.jl
@@ -1,4 +1,4 @@
-export Differential, expand_derivatives, @deriv
+export Differential, expand_derivatives, @derivatives
 
 
 struct Differential <: Function
@@ -63,7 +63,7 @@ function _differential_macro(x)
     lhss = Symbol[]
     x = flatten_expr!(x)
     for di in x
-        @assert di isa Expr && di.args[1] == :~ "@deriv expects a form that looks like `@deriv D''~t E'~t`"
+        @assert di isa Expr && di.args[1] == :~ "@derivatives expects a form that looks like `@derivatives D''~t E'~t`"
         lhs = di.args[2]
         rhs = di.args[3]
         order, lhs = count_order(lhs)
@@ -75,7 +75,7 @@ function _differential_macro(x)
     ex
 end
 
-macro deriv(x...)
+macro derivatives(x...)
     esc(_differential_macro(x))
 end
 
diff --git a/src/variables.jl b/src/variables.jl
index 88a3fb22ca..4777eed673 100644
--- a/src/variables.jl
+++ b/src/variables.jl
@@ -1,4 +1,4 @@
-export Variable, @variable, @param
+export Variable, @variables, @parameters
 
 
 struct Variable <: Expression
@@ -70,9 +70,9 @@ function _parse_vars(macroname, known, x)
     push!(ex.args, build_expr(:tuple, var_names))
     return ex
 end
-macro variable(xs...)
+macro variables(xs...)
     esc(_parse_vars(:Variable, false, xs))
 end
-macro param(xs...)
+macro parameters(xs...)
     esc(_parse_vars(:Param, true, xs))
 end
diff --git a/test/derivatives.jl b/test/derivatives.jl
index e6bf9e0065..999cad9a70 100644
--- a/test/derivatives.jl
+++ b/test/derivatives.jl
@@ -2,9 +2,9 @@ using ModelingToolkit
 using Test
 
 # Derivatives
-@param t σ ρ β
-@variable x(t) y(t) z(t)
-@deriv D'~t D2''~t
+@parameters t σ ρ β
+@variables x(t) y(t) z(t)
+@derivatives D'~t D2''~t
 
 @test isequal(expand_derivatives(D(t)), 1)
 @test isequal(expand_derivatives(D(D(t))), 0)
@@ -47,7 +47,7 @@ jac = calculate_jacobian(sys)
 @test isequal(jac[3,3], -1*β)
 
 # Variable dependence checking in differentiation
-@variable a(t) b(a)
+@variables a(t) b(a)
 @test !isequal(D(b), 0)
 
 @test isequal(expand_derivatives(D(x * y)), simplify_constants(y*D(x) + x*D(y)))
diff --git a/test/simplify.jl b/test/simplify.jl
index 6853ec6e8e..be6c1554df 100644
--- a/test/simplify.jl
+++ b/test/simplify.jl
@@ -1,8 +1,8 @@
 using ModelingToolkit
 using Test
 
-@param t
-@variable x(t) y(t) z(t)
+@parameters t
+@variables x(t) y(t) z(t)
 
 null_op = 0*t
 @test isequal(simplify_constants(null_op), 0)
diff --git a/test/system_construction.jl b/test/system_construction.jl
index 876b265ffc..120607e6b6 100644
--- a/test/system_construction.jl
+++ b/test/system_construction.jl
@@ -2,9 +2,9 @@ using ModelingToolkit
 using Test
 
 # Define some variables
-@param t σ ρ β
-@variable x(t) y(t) z(t)
-@deriv D'~t
+@parameters t σ ρ β
+@variables x(t) y(t) z(t)
+@derivatives D'~t
 
 # Define a differential equation
 eqs = [D(x) ~ σ*(y-x),
@@ -32,7 +32,7 @@ end
 test_vars_extraction(de, de2)
 
 @testset "time-varying parameters" begin
-    @param σ′(t)
+    @parameters σ′(t)
     eqs = [D(x) ~ σ′*(y-x),
            D(y) ~ x*(ρ-z)-y,
            D(z) ~ x*y - β*z]
@@ -46,9 +46,9 @@ test_vars_extraction(de, de2)
 end
 
 # Conversion to first-order ODEs #17
-@deriv D3'''~t
-@deriv D2''~t
-@variable u(t) u_tt(t) u_t(t) x_t(t)
+@derivatives D3'''~t
+@derivatives D2''~t
+@variables u(t) u_tt(t) u_t(t) x_t(t)
 eqs = [D3(u) ~ 2(D2(u)) + D(u) + D(x) + 1
        D2(x) ~ D(x) + 2]
 de = DiffEqSystem(eqs, t)
@@ -84,8 +84,8 @@ end
 
 generate_function(ns)
 
-@deriv D'~t
-@param A B C
+@derivatives D'~t
+@parameters A B C
 _x = y / C
 eqs = [D(x) ~ -A*x,
        D(y) ~ A*x - B*_x]
@@ -100,8 +100,8 @@ test_vars_extraction(de, DiffEqSystem(eqs))
 end
 
 # Now nonlinear system with only variables
-@variable x y z
-@param σ ρ β
+@variables x y z
+@parameters σ ρ β
 
 # Define a nonlinear system
 eqs = [0 ~ σ*(y-x),
diff --git a/test/variable_parsing.jl b/test/variable_parsing.jl
index 9a97f4da19..759652f110 100644
--- a/test/variable_parsing.jl
+++ b/test/variable_parsing.jl
@@ -1,10 +1,10 @@
 using ModelingToolkit
 using Test
 
-@param t
-@variable x(t)
-@variable y(t)
-@variable z(t)
+@parameters t
+@variables x(t)
+@variables y(t)
+@variables z(t)
 x1 = Variable(:x, [t])
 y1 = Variable(:y, [t])
 z1 = Variable(:z, [t])
@@ -15,7 +15,7 @@ z1 = Variable(:z, [t])
 @test convert(Expr, y) == :y
 @test convert(Expr, z) == :z
 
-@param begin
+@parameters begin
     t
     s
 end
@@ -27,7 +27,7 @@ s1 = Variable(:s; known = true)
 @test convert(Expr, s) == :s
 @test convert(Expr, cos(t + sin(s))) == :(cos(t + sin(s)))
 
-@deriv D'~t
+@derivatives D'~t
 D1 = Differential(t)
 @test D1 == D
 @test convert(Expr, D) == D