APL (Dyalog), 2 bytes

⍣=

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⍣ Is an operator that can be used like (function⍣condition) ⍵

It applies the function to ⍵ until (f ⍵) condition ⍵ returns true. Therefore ⍣= takes a function as its left argument and applies it to its right argument until f ⍵ = ⍵

APL (Dyalog), 2 bytes

⍣=

Try it online!

NB: I define O←⍣= in the the input section due to a bug in that derived monadic operators can't be defined in the way that TIO likes to define things.

⍣ Is an operator that can be used like (function⍣condition) ⍵

It applies the function, f, to ⍵ until (f ⍵) condition ⍵ returns true. 

⍣= is a derived monadic operator that takes a monadic function, f, as its left argument and applies it to its right argument, ⍵, until f ⍵ = ⍵

APL (Dyalog), 2 bytes

⍣=

Try it online!

⍣ Is an operator that can be used like (function⍣condition) ⍵

It applies the function to ⍵ until (f ⍵) condition ⍵ returns true. Therefore ⍣= takes a function as it's left argument and applies it to it's right argument until f ⍵ = ⍵

APL (Dyalog), 2 bytes

⍣=

Try it online!

⍣ Is an operator that can be used like (function⍣condition) ⍵

It applies the function to ⍵ until (f ⍵) condition ⍵ returns true. Therefore ⍣= takes a function as its left argument and applies it to its right argument until f ⍵ = ⍵

APL (Dyalog), 2 bytes

⍣=

Try it online!

APL (Dyalog), 2 bytes

⍣=

Try it online!

⍣ Is an operator that can be used like (function⍣condition) ⍵

It applies the function to ⍵ until (f ⍵) condition ⍵ returns true. Therefore ⍣= takes a function as it's left argument and applies it to it's right argument until f ⍵ = ⍵