E01095: '<=?' and '>=?' were removed - on equal values '<?' and '>?' now give the LEFT operand, so write '<?' for '<=?' and '>?' for '>=?'

What went wrong

'<=?' and '>=?' no longer exist. They were the comparison coalescing operators that kept the LEFT operand when two values compare equal, while '<?' and '>?' kept the RIGHT one. That difference is gone: on a tie ('<=>' gives 0) '<?' and '>?' now give the LEFT operand too, so each removed operator has a plain replacement. This no longer compiles:

rtn: first <=? second //removed: write '<?', which gives the left operand on a tie

The grammar keeps the two tokens only to give this error, as it keeps 'break' and 'return'.

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 963 (How does the <? coalescing minimum operator work in EK9?)
• ek9 -q 243 (How do coalescing operators handle unset values in EK9?)

How to fix it

Write '<?' in place of the removed '<=?', and '>?' in place of the removed '>=?'. The result is the same: on equal values the left operand is returned.

rtn: first <? second

If you want the RIGHT operand on a tie (what '<?' and '>?' used to give), swap the operands: 'second <? first' returns 'first' when they compare equal.

Common causes

• Code written before the tie rule was made the same for all four operators
• Java habit: '<=' and '>=' have an inclusive form, so an inclusive coalescing form was expected
• AI-written code that remembers the old operator family

See also

• E01095: '<=?' and '>=?' were removed (this error)
• E07187: '<?' and '>?' on a type whose values can be of different run-time types
• E07620: '<?' or '>?' on a type that has no '<=>' (or none that survives)
• E08269: a coalescing operator mixed with a different binary operator without parentheses
• https://ek9.io/operators.html#coalescing

Examples

Every example is compiled by the EK9 compiler: the first fails exactly as captioned, the others fix it.

Fails with E01095: '<=?' and '>=?' were removed - on equal values '<?' and '>?' now give the LEFT operand, so write '<?' for '<=?' and '>?' for '>=?'

#!ek9
defines module error.e01095.bad

  defines function

    earlierStart()
      ->
        first as Time
        second as Time
      <- rtn as Time?

      rtn: first <=? second //removed: write '<?', which gives the left operand on a tie

    laterStart()
      ->
        first as Time
        second as Time
      <- rtn as Time?

      rtn: first >=? second //removed: write '>?', which gives the left operand on a tie

Fixed: Write '<?' or '>?' - on a tie they give the left operand

#!ek9
defines module error.e01095.good

  defines function

    earlierStart()
      ->
        first as Time
        second as Time
      <- rtn as Time?

      rtn: first <? second

    laterStart()
      ->
        first as Time
        second as Time
      <- rtn as Time?

      rtn: first >? second

Questions and answers

These Q&A entries show E01095 and its fix:

• Q963: How does the <? coalescing minimum operator work in EK9?