add evaluable functor: asin

[ichiban]

#144

[codecov-commenter]

Codecov Report

Merging #168 (868ac51) into main (5c26462) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #168   +/-   ##
=======================================
  Coverage   95.43%   95.44%           
=======================================
  Files          19       19           
  Lines        5979     5992   +13     
=======================================
+ Hits         5706     5719   +13     
  Misses        228      228           
  Partials       45       45           

Impacted Files	Coverage Δ
engine/number.go	100.00% <100.00%> (ø)

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