Merge pull request #22 from TuringLang/mt/fix_turing_700

Fix Turing issue 700

src/Bijectors.jl

@@ -18,7 +18,8 @@ export  TransformDistribution,
 
 const DEBUG = Bool(parse(Int, get(ENV, "DEBUG_BIJECTORS", "0")))
 
-_eps(::Type{T}) where {T} = eps(T)
+# Workaround for eps(::ForwardDiff.Dual)
+_eps(::Type{T}) where {T} = T(eps(T))
 _eps(::Type{Real}) = eps(Float64)
 function __init__()
     @require ForwardDiff="f6369f11-7733-5829-9624-2563aa707210" @eval begin
@@ -62,8 +63,8 @@ end
 #############
 
 const TransformDistribution{T<:ContinuousUnivariateDistribution} = Union{T, Truncated{T}}
-@inline function _clamp(x::Real, dist::TransformDistribution)
-    ϵ = eps(x)
+@inline function _clamp(x::T, dist::TransformDistribution) where {T <: Real}
+    ϵ = _eps(T)
     bounds = (minimum(dist) + ϵ, maximum(dist) - ϵ)
     clamped_x = ifelse(x < bounds[1], bounds[1], ifelse(x > bounds[2], bounds[2], x))
     DEBUG && @debug "x = $x, bounds = $bounds, clamped_x = $clamped_x"