The elseif and else blocks are optional, and as many elseif blocks as desired can be used. Here it is in action: julia> function test(x, y) If the condition expression x y is evaluated, and if it is true, the corresponding block is evaluated if neither expression is true, the else block is evaluated. Here is the anatomy of the if- elseif- else conditional syntax: if x y Although it is typical, there is no requirement that begin blocks be multiline or that chains be single-line: julia> begin x = 1 y = 2 x + y endĬonditional evaluation allows portions of code to be evaluated or not evaluated depending on the value of a boolean expression. This syntax is particularly useful with the terse single-line function definition form introduced in Functions. Since these are fairly small, simple expressions, they could easily be placed onto a single line, which is where the chain syntax comes in handy: julia> z = (x = 1 y = 2 x + y) Here's an example of a begin block: julia> z = begin The value of both compound expression constructs is that of the last subexpression. There are two Julia constructs that accomplish this: begin blocks and chains. Sometimes it is convenient to have a single expression which evaluates several subexpressions in order, returning the value of the last subexpression as its value. Everyday programming requires no direct usage of tasks, but certain problems can be solved much more easily by using tasks. This is a powerful construct: both exception handling and cooperative multitasking are implemented in Julia using tasks. Tasks are not so standard: they provide non-local control flow, making it possible to switch between temporarily-suspended computations. The first five control flow mechanisms are standard to high-level programming languages. Exception Handling: try- catch, error and throw.Repeated Evaluation: Loops: while and for.Short-Circuit Evaluation: logical operators & (“and”) and || (“or”), and also chained comparisons.Conditional Evaluation: if- elseif- else and ?: (ternary operator).Julia provides a variety of control flow constructs: Instrumenting Julia with DTrace, and bpftrace.Reporting and analyzing crashes (segfaults).
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