sourcewalk introduces blocks

[oxinabox]

MWE:

using MacroTools
using MacroTools: textwalk

code = """
Rule(x -> -sin(x))
Rule(x -> 1 + tan(x)^2)
""";

after = textwalk(code) do expr
    @capture(expr, Rule(v_)) && return v
    return expr
end

println(after)

Output:

(x->begin
        -(sin(x))
    end)
(x->begin
        1 + tan(x) ^ 2
    end)

[oxinabox]

Workaround:

 textwalk(code) do expr
    @capture(expr, Rule(v_)) && return MacroTools.postwalk(MacroTools.unblock, v)
    return expr
end

Though that still changes spacing,
and adds extra backets arround sin(x) and arraound the whole expression

Output

(x->-(sin(x)))
(x->1 + tan(x) ^ 2)

[MikeInnes]

This is unfortunately due to Base's default parsing/printing of lambdas:

julia> :(x->1)
:(x->begin
          #= REPL[1]:1 =#
          1
      end)

Would be great to fix, but unfortunately might require a fork of the Expr printing code (though there are likely several reasons to do this).

[MikeInnes]

Alternatively, since Expr(:->, :x, 1) seems to do the right thing, maybe we can just tweak CSTParser to not insert the block / line number.