nearest can deal with units

Author: emmt

NEWS.md

@@ -11,6 +11,8 @@ This page describes the most important changes in `TypeUtils`. The format is bas
 - With multiple arguments, `get_precision(x, y...)` yields the best precision of all the
   given arguments.
 
+- `nearest(T, x)` can deal with dimensionful numbers and types.
+
 
 ## Version 1.9.0 (2025-06-20)
 

ext/TypeUtilsUnitfulExt.jl

@@ -33,4 +33,10 @@ TypeUtils.adapt_precision(::Type{T}, x::Quantity{S,D,U}) where {T<:Precision,D,U
 TypeUtils.adapt_precision(::Type{T}, ::Type{Quantity{S,D,U}}) where {T<:Precision,S,D,U} =
     Quantity{adapt_precision(T, S), D, U}
 
+TypeUtils.nearest(::Type{Q}, x::Q) where {T,D,U,Q<:AbstractQuantity{T,D,U}} = x
+TypeUtils.nearest(::Type{Q}, x::AbstractQuantity{<:Any,D,U}) where {T,D,U,Q<:AbstractQuantity{T,D,U}} =
+    nearest(T, ustrip(x))*unit(x)
+TypeUtils.nearest(::Type{Q}, x::Number) where {T,D,U,Q<:AbstractQuantity{T,D,U}} =
+    nearest(Q, uconvert(unit(Q), x))
+
 end # module

test/runtests.jl

@@ -266,6 +266,12 @@ same_value_and_type(x::T, y::T) where {T} = (x === y) || (x == y)
         let vals = (1.3, -2.7, pi, 42)
             @test map(nearest(Int), vals) === map(x -> nearest(Int, x), vals)
         end
+        # `nearest` with dimensionful numbers.
+        @test @inferred(nearest(typeof(1.0u"m"), -2.3u"m")) === -2.3u"m"
+        @test @inferred(nearest(typeof(1u"cm"), -2.3u"m")) === -230u"cm"
+        @test @inferred(nearest(typeof(1u"mm"), -2.3u"m")) === -2300u"mm"
+        @test_throws Unitful.DimensionError @inferred(nearest(typeof(1u"mm"), 81.0u"m/s"))
+        @test @inferred(nearest(typeof(1u"mm/s"), 871.0u"m/hr")) === 242u"mm/s"
     end
 
     @testset "Array axes and size" begin