compile.txt

$ ponyc -d .
Building builtin -> /Users/nlalevee/dev/pony/git/packages/builtin
Building . -> /Users/nlalevee/dev/pony/pony-mysandbox/git/src/trn_param
Building debug -> /Users/nlalevee/dev/pony/git/packages/debug
Error:
/Users/nlalevee/dev/pony/pony-mysandbox/git/src/trn_param/trn_param.pony:9:16: receiver type is not a subtype of target type
    str1.append(str2)
               ^
    Info:
    /Users/nlalevee/dev/pony/pony-mysandbox/git/src/trn_param/trn_param.pony:9:5: receiver type: String trn!
        str1.append(str2)
        ^
    /Users/nlalevee/dev/pony/git/packages/builtin/string.pony:623:3: target type: String ref
      fun ref append(seq: ReadSeq[U8], offset: USize = 0, len: USize = -1)
      ^
    /Users/nlalevee/dev/pony/pony-mysandbox/git/src/trn_param/trn_param.pony:9:16: this would be possible if the arguments and return value were all sendable
        str1.append(str2)
                   ^
    /Users/nlalevee/dev/pony/pony-mysandbox/git/src/trn_param/trn_param.pony:5:15: String trn! is not a subtype of String ref: trn! is not a subtype of ref
        var str1: String trn = recover String.create().append("hum...") end
                  ^
[

trn_param.pony

use "debug"

actor Main
  new create(env: Env) =>
    var str1: String trn = recover String.create().append("hum...") end
    var str2: String trn = recover String.create().append("arg!") end
    Debug.out(str1)
    Debug.out(str2)
    str1.append(str2)
    Debug.out(str1)