lean/rust style if let #34

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opened 2026-07-01 11:28:41 +02:00 by st · 0 comments

st commented

2026-07-01 11:28:41 +02:00

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a function that recognizes string elements and extracts their contents can be written:
def Inline.string? (inline : Inline) : Option String :=
  match inline with
  | Inline.string s => some s
  | _ => none
An alternative way of writing this function's body uses if together with let:
def Inline.string? (inline : Inline) : Option String :=
  if let Inline.string s := inline then
    some s
  else none

> a function that recognizes string elements and extracts their contents can be written: > > ``` > def Inline.string? (inline : Inline) : Option String := > match inline with > | Inline.string s => some s > | _ => none > ``` > > An alternative way of writing this function's body uses if together with let: > > ``` > def Inline.string? (inline : Inline) : Option String := > if let Inline.string s := inline then > some s > else none > ```