Improve explicit imports hygiene

- Remove unused runtime dependencies (ModelingToolkit, NonlinearSolve,
  QuasiMonteCarlo, SparseArrays, Symbolics)
- Make LinearAlgebra imports explicit (norm, I)
- Remove broken/incomplete code from utils.jl
- Clean up test dependencies, remove unused packages
- Make test imports more explicit where possible
- Add ExplicitImports.jl tests to verify import hygiene

Files modified:
- Project.toml: Reduced to only LinearAlgebra dependency
- src/FastSolvers.jl: Explicit imports from LinearAlgebra
- src/utils.jl: Removed broken sample_collocation_points function
- test/Project.toml: Added ExplicitImports, removed unused deps
- test/runtests.jl: Made imports more explicit
- test/explicit_imports.jl: New file for CI import checks

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ChrisRackauckas

Project.toml

@@ -1,21 +1,11 @@
 name = "FastSolvers"
 uuid = "afc03370-3a10-4444-b401-158123c3c69f"
-authors = ["Anant Thazhemadam <anant.thazhemadam@gmail.com>"]
 version = "0.1.0"
+authors = ["Anant Thazhemadam <anant.thazhemadam@gmail.com>"]
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
-ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78"
-NonlinearSolve = "8913a72c-1f9b-4ce2-8d82-65094dcecaec"
-QuasiMonteCarlo = "8a4e6c94-4038-4cdc-81c3-7e6ffdb2a71b"
-SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
-Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 
 [compat]
 LinearAlgebra = "1.10"
-ModelingToolkit = "9.20.0"
-NonlinearSolve = "3.13.1"
-QuasiMonteCarlo = "0.3.3"
-SparseArrays = "1.10"
-Symbolics = "5.32.0"
 julia = "1.10"

src/FastSolvers.jl

@@ -1,14 +1,5 @@
 module FastSolvers
-using SparseArrays
-using NonlinearSolve
-using LinearAlgebra
-using QuasiMonteCarlo
-
-import QuasiMonteCarlo.SamplingAlgorithm
-import QuasiMonteCarlo.sample
-
-import ModelingToolkit.PDESystem
-import ModelingToolkit.Equation
+using LinearAlgebra: norm, I
 
 include("utils.jl")
 

src/utils.jl

@@ -1,37 +1 @@
-function sample_collocation_points(
-        domain::T, num_points::Tuple{Int, Int}, sampler::SamplingAlgorithm) where {T}
-    d = length(domain)
-    ni, nb = num_points
-
-    # Sample interior points
-    lb = []
-    ub = []
-    for i in 1:d
-        push!(lb, domain[i].left)
-        push!(ub, domain[i].right)
-    end
-    interior_points = sample(ni, lb, ub, sampler)
-
-    # Sample boundary points
-    nbcs = length(bcs)
-    nb_local = floor(Int, nb / nbcs)
-    boundary_points = []
-    for j in 1:nbcs
-        mask = []
-        bcs_local = bcs[j]
-        for i in 1:d
-            if typeof(bcs_local.lhs.arguments[i]) != SymbolicUtils.BasicSymbolic
-                push!(mask, i)
-            end
-        end
-        lb_local = lb[mask]
-        ub_local = ub[mask]
-        push!(
-            boundary_points, QuasiMonteCarlo.sample(nb_local, lb_local, ub_local, sampler))
-    end
-    return interior_points, reduce(vcat, boundary_points)
-end
-
-function LinearAlgebra.UpperTriangular(a::Float64)
-    return a
-end
+# Utility functions for FastSolvers

test/Project.toml

@@ -1,17 +1,10 @@
 [deps]
-BenchmarkTools = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
-DomainSets = "5b8099bc-c8ec-5219-889f-1d9e522a28bf"
+ExplicitImports = "7d51a73a-1435-4ff3-83d9-f097790105c7"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
-LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
-ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78"
 NonlinearSolve = "8913a72c-1f9b-4ce2-8d82-65094dcecaec"
-OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
 QuasiMonteCarlo = "8a4e6c94-4038-4cdc-81c3-7e6ffdb2a71b"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-DomainSets = "0.7.14"
-ModelingToolkit = "9.20.0"
-OrdinaryDiffEq = "6.84.0"
 julia = "1.10"

test/explicit_imports.jl

@@ -0,0 +1,8 @@
+using ExplicitImports
+using FastSolvers
+using Test
+
+@testset "ExplicitImports" begin
+    @test check_no_implicit_imports(FastSolvers) === nothing
+    @test check_no_stale_explicit_imports(FastSolvers) === nothing
+end

test/runtests.jl

@@ -2,10 +2,8 @@ using FastSolvers
 using Test
 using ForwardDiff
 using QuasiMonteCarlo
-using SparseArrays
-using LinearAlgebra
-using NonlinearSolve
-using BenchmarkTools
+using SparseArrays: spzeros
+using NonlinearSolve: NonlinearLeastSquaresProblem, solve
 
 @testset "RKHS kernels" begin
     include("kernels/interface.jl")
@@ -24,3 +22,7 @@ end
     include("rfnn/derivatives.jl")
     include("rfnn/function_approx.jl")
 end
+
+@testset "Explicit Imports" begin
+    include("explicit_imports.jl")
+end