. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 30.8 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 401 30.9 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1912 106.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1913 106.14 Package Images firstlast(Val(true)) "First"CHAPTER 12. TYPES 157 julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401 30.8 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 402 30.9 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1909 106.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1910 106.14 Package Images with 2 methods) julia> firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 30.8 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 401 30.9 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1909 106.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1910 106.14 Package Images with 2 methods) julia> firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 30.8 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 401 30.9 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1909 106.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1910 106.14 Package Images with 2 methods) julia> firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 30.8 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 401 30.9 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1900 105.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1901 105.14 Package Images with 2 methods) julia> firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 30.7 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 397 30.8 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1859 105.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1860 105.14 Package Images with 2 methods) julia> firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 30.7 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 397 30.8 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1859 105.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1860 105.14 Package Images with 2 methods) julia> firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 30.7 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 397 30.8 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1859 105.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1860 105.14 Package Images with 2 methods) julia> firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last" For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 373CONTENTS vi 29.7 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 374 29.8 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1576 101.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1577 101.14 Package Images firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last"CHAPTER 11. TYPES 148 For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 373CONTENTS vi 29.7 System and Package Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . 374 29.8 Debugging and profiling . Union Optimizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1576 101.13 System Image Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1577 101.14 Package Images firstlast(Val(true)) "First" julia> firstlast(Val(false)) "Last"CHAPTER 11. TYPES 148 For consistency across Julia, the call site should always pass a Val instance rather than using a type, i.e.,