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6687 :: How to codegenerate with Nim?

• c0ffee (orginal) [2020-08-16T22:05:40+02:00] view original

  Hello.

  In C# reflection can be used to get all types from assembly, filter them by type info such as attributes, interfaces, etc. Then on every filtered type run some arbitrary code, in this case generate code according to reflection type info data. Generating code for C# this way doesn't happen during compilation, and I'd like to know if Nim could generate Nim code during compilation phase.

  1. Is there a way to get all types, filter all types?
  2. Are there ways to add meta data(similar to C# attributes) to various Nim AST nodes?
  3. Can this meta data be used by compiler to generate new code during compilation phase?
  4. If above example is not possible what are other options to do something similar for code generation with Nim?

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• Araq (orginal) [2020-08-17T08:57:53+02:00] view original

  The introspection capabilities of Nim's macro system do not allow for "get all types" etc.

  One good option is to use the Nim compiler as a library, see https://github.com/nim-lang/Nim/blob/devel/tests/compilerapi/tcompilerapi.nim for an example.

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• mratsim (orginal) [2020-08-19T10:08:19+02:00] view original

  I usually store all the information in a declarative DSL and run a macro for codegen on it, examples:

  • opcodes for a JIT assembler: https://github.com/mratsim/photon-jit/blob/ef195440/photon_jit/x86_64/x86_64_ops.nim#L24-L57
  • opcodes for an emulator: https://github.com/mratsim/glyph/blob/8b278c5e/glyph/snes/opcodes.nim#L16-L32
  • state machine: https://github.com/mratsim/Synthesis
  • Emulating classes with ADTs/variants: https://github.com/mratsim/trace-of-radiance/blob/99f7d85d/trace_of_radiance/support/emulate_classes_with_ADTs.nim
  • neural network DSL: https://github.com/mratsim/Arraymancer#a-simple-two-layers-neural-network

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