Better error message for anonymous functions (#263)

* Better error message for anonymous functions

* Bump version

* Fix format

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: devmotion

Project.toml

@@ -1,6 +1,6 @@
 name = "DynamicPPL"
 uuid = "366bfd00-2699-11ea-058f-f148b4cae6d8"
-version = "0.11.3"
+version = "0.11.4"
 
 [deps]
 AbstractMCMC = "80f14c24-f653-4e6a-9b94-39d6b0f70001"

src/compiler.jl

@@ -109,6 +109,11 @@ function build_model_info(input_expr)
     # Break up the model definition and extract its name, arguments, and function body
     modeldef = MacroTools.splitdef(input_expr)
 
+    # Check that the function has a name
+    # https://github.com/TuringLang/DynamicPPL.jl/issues/260
+    haskey(modeldef, :name) ||
+        throw(ArgumentError("anonymous functions without name are not supported"))
+
     # Print a warning if function body of the model is empty
     warn_empty(modeldef[:body])
 

test/compiler.jl

@@ -441,12 +441,25 @@ end
             return [10.0, 10.0] ~ MvNormal(m, 0.5 * ones(2))
         end) isa Function
 
-        @model function array_literal_model()
+        @model function array_literal_model2()
             # `assume` and literal `observe`
             m ~ MvNormal(2, 1.0)
             return [10.0, 10.0] ~ MvNormal(m, 0.5 * ones(2))
         end
 
-        @test array_literal_model()() == [10.0, 10.0]
+        @test array_literal_model2()() == [10.0, 10.0]
+    end
+
+    # https://github.com/TuringLang/DynamicPPL.jl/issues/260
+    @testset "anonymous function" begin
+        error = ArgumentError("anonymous functions without name are not supported")
+        @test_throws LoadError(@__FILE__, (@__LINE__) + 1, error) @macroexpand begin
+            @model function (x)
+                return x ~ Normal()
+            end
+        end
+        @test_throws LoadError(@__FILE__, (@__LINE__) + 1, error) @macroexpand begin
+            model = @model(x -> (x ~ Normal()))
+        end
     end
 end