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Pure Roc implementation of Result.alterErr

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Marten/Qqwy 2022-07-07 22:44:13 +02:00 • committed by Folkert
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17
crates/compiler/builtins/roc/Result.roc
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@ -92,3 +92,20 @@ after = \result, transform ->
transform v
Err e ->
Err e
## If the result is `Err`, transform the entire result by running a conversion
## function on the value the `Err` holds. Then return that new result.
##
## (If the result is `Ok`, this has no effect. Use `after` to transform an `Ok`.)
##
## >>> Result.afterErr (Ok 10) \errorNum -> Str.toNat errorNum
##
## >>> Result.afterErr (Err "42") \errorNum -> Str.toNat errorNum
after : Result a err, (err -> Result a otherErr) -> Result a otherErr
after = \result, transform ->
when result is
Ok v ->
v
Err e ->
transform e