From @zoffixznet

When an undetached method is called on a range of an Int, you get a nice message about precedence​:

BrokenRobot m​: my $x = ^5.grep​: *.is-prime # LTA
camelia rakudo-moar d075c8​: OUTPUT«Potential difficulties​:␤ Precedence of ^ is looser than method call; please parenthesize␤ at <tmp>​:1␤ ------> 3my $x = ^57⏏5.grep​: *.is-prime # LTA␤»

The message, however, isn't shown if we use infinity (a Num) for the range​:

BrokenRobot m​: my $x = ^∞.grep​: *.is-prime # LTA
camelia rakudo-moar d075c8​: OUTPUT«Method 'is-prime' not found for invocant of class 'Num'␤ in block <unit> at <tmp> line 1␤␤»

Or, it seems, any non-Int​:

BrokenRobot m​: my $x = ^5.5.grep​: *.is-prime # LTA
camelia rakudo-moar d075c8​: OUTPUT«Method 'is-prime' not found for invocant of class 'Rat'␤ in block <unit> at <tmp> line 1␤␤»

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ZZ | https://twitter.com/zoffix