JuliaLang/julia

replace: allow transform function as first argument?

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#24,598 opened on Nov 13, 2017

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Description

The replace function allows a string, an s"..." replacement specifier or a function as its third argument. For the sake of do syntax, it might make sense to support the function as the first argument, like so:

julia> replace("Hello, world.", r"\w+") do word
           n = 0
           for c in word
               n += lowercase(c) in "aeiou"
           end
           return n
       end
"2, 1."

If someone decides to do this, while they're at it, an explanation of replacement patterns – i.e. s"..." strings and some more examples in the replace docs wouldn't hurt. E.g.:

julia> replace("Hello, world.", r"(\w+)(\W+)(\w+)", s"\3\2\1")
"world, Hello."

Contributor guide

Research direction
Explore the current `replace` method signatures in base/reduce.jl, understand how do block syntax works, and add a new method that accepts a function as the first argument. Update documentation with examples of replacement patterns.
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None
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JuliaGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70