feat: Use gg to generate code for pairs

[Xuanwo]

This is a demo PR for evaluations.

Related to #607.

• Is go-codegen more friendly than go template?
• Is go-codegen easier to learn/use/understanding?

[codecov]

Codecov Report

Merging #728 (42a3ab9) into master (ff8dbd1) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #728   +/-   ##
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  Coverage   12.47%   12.47%           
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  Files          22       22           
  Lines        1483     1483           
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  Hits          185      185           
  Misses       1291     1291           
  Partials        7        7           

Flag	Coverage Δ
unittests	12.47% <ø> (ø)

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[Xuanwo]

ping @JinnyYi to take another look.

[Xuanwo]

I will extend it to more complex functions like operations tomorrow.

[Xuanwo]

I re-design the API of codegen that inspired by jen, please take a look.

The code can't be compiled so fat, I will implement it if it looks good.

[JinnyYi]

I re-design the API of codegen that inspired by jen, please take a look.

I think it‘s easy to read and translate into the final generated code.

[Xuanwo]

ping @JinnyYi for review.

[JinnyYi]

LGTM. Only a small doubt, is it possible or necessary to keep only Description for Pair?

[Xuanwo]

LGTM. Only a small doubt, is it possible or necessary to keep only Description for Pair?

Yes, we have to. We use originalDescription here because we need to make sure the remaining templates works. We will remove originalDescription finally!

[Xuanwo]

I will bump a version about gg, please merge this PR after update, thanks!

[JinnyYi]

LGTM.