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Improve some List docs

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Richard Feldman 2023-07-23 13:56:16 -04:00
parent dca55263e3
commit 64c49ddbc9
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1 changed files with 11 additions and 2 deletions
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13
crates/compiler/builtins/roc/List.roc
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@ -1182,8 +1182,17 @@ mapTry = \list, toResult ->
Result.map (toResult elem) \ok ->
List.append state ok
## This is the same as `iterate` but with [Result] instead of `[Continue, Break]`.
## Using `Result` saves a conditional in `mapTry`.
## Same as [List.walk], except you can stop walking early by returning `Err`.
##
## ## Performance Details
##
## Compared to [List.walk], this can potentially visit fewer elements (which can
## improve performance) at the cost of making each step take longer.
## However, the added cost to each step is extremely small, and can easily
## be outweighed if it results in skipping even a small number of elements.
##
## As such, it is typically better for performance to use this over [List.walk]
## if returning `Break` earlier than the last element is expected to be common.
walkTry : List elem, state, (state, elem -> Result state err) -> Result state err
walkTry = \list, init, func ->
walkTryHelp list init func 0 (List.len list)