I do:

dub init simple_type_theory
cd simple_type_theory
dub generate visuald

Errors:

C:\Users\FruitfulApproach\Desktop\_SIMPLE_TYPE_THEORY\simple_type_theory>dub generate visuald simple_type_theory
Building package simple_type_theory in C:\Users\FruitfulApproach\Desktop\_SIMPLE_TYPE_THEORY\simple_type_theory\
Cannot open file `.dub\simple_type_theory.visualdproj' in mode `wb' (No such file or directory)