Optional "ㅇ" at syllable initial position causes undesirable syllable segmentation

[AlienKevin]

Observations

• Typing the key sequence "hangyl" produces "항을" instead of the expected "한글".
  A "ㅇ" is auto-inserted before "yl" to produce "을". The sequence "hangyl" is undesirably segmented into "hang" and "yl".

• Typing the key sequence "haseixio" or "haseiio" produces "핫에요" instead of the expected "하세요".
  A "ㅇ" is auto-inserted before "ei". The sequence "hasei" is undesirably segmented into "has" and "ei".

Reason

Syllable initial "ㅇ" is required in some cases to disambiguate syllable boundary in Hangul. Hence, input methods like HNC Romaja on macOS require the input of "ㅇ" to eliminate ambiguity.

Fix

Comment out the following line in hangyl.schema.yaml:

speller:
  ...
  algebra:
    # - derive/(^|[ '])x?([aeiouy])/$1$2/

Implications of the fix

"ㅇ" is always required at the syllabe initial position:

• The key sequence "an" produces "ㅏㄴ". To produce the syllable "안", type "xan" or "qan" instead.
• The key sequence "haseiio" produces "하세ㅛ". To produce the word "하세요", type "haseixio" or "haseiqio" instead.