The usual disambiguators: 
{; ... }   # Block
+{ ... }   # Hash constructor

[download]

For example, 

>perl -ce"{ 1, 2; }"
syntax error at -e line 1, near "; }"
-e had compilation errors.

>perl -ce"{; 1, 2; }"
-e syntax OK

>perl -ce"map { f() }, @a"
syntax error at -e line 1, near "},"
-e had compilation errors.

>perl -ce"map +{ f() }, @a"
-e syntax OK

[download]

In reply to Re: failure to compile list eval in block by ikegami
in thread failure to compile list eval in block by ed_hoch

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