perl -Mutf8 -MMath::Trig -E 'use constant π => pi; say π'
3.14159265358979 
perl -Mutf8 -MMath::Trig=:pi -C -E 'use constant π² => pi2; say π²'
Unrecognized character \x{b2}; marked by <-- HERE after constant π<-- HERE near column 15 at -e line 1. 
perl -Mutf8 -MMath::Trig=:pi -C -E 'use constant q(π²) => pi2; say π²'
Constant name 'π²' has invalid characters at -e line 1. BEGIN failed--compilation aborted at -e line 1.

In reply to Unicode constant by Anonymous Monk

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