Block Structure

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Block Structure

As in many C tradition languages (C, C++, Java, Perl, Python, Tcl, and csh), E statements and expressions appear only inside function and object definitions. Actually, E has no statements -- only expressions. The control-flow constructs, like the if expression, that one might expect to be statements are instead expressions in E.

The next chapter, Control Flow Expressions , covers the ones most like traditional control-flow. The following chapter, The for Loops, covers E's main iteration construct. Then, in The define Expressions , we see how to define new variables, functions, normal objects, and message plumbing objects. Finally, Inheritance by Delegation , introduces the class expression, which supports a pattern of delegating messages that mirrors the conventional notion of inheritance.

Quick Links to Sequential E Control Structures

Control Flow Expressions

if (cond) { then-expr } else { else-expr }
left && right
left || right
{ nested-expr }
escape hatch { body }
while (cond) { body }
try { attempt } catch ex { handler } finally { exit }
switch (specimen) { match pattern { body } ... }

The for Loops

for value-patt in collection { body }
for key-patt => value-patt in collection { body }

Defining...

variables: def pattern := expr

functions: def name(patterns) guard { body }

objects: def name { methods matchers }

... by delegation: def name extends expr { methods }

plumbing: def name match pattern { body }

Inheritance by Delegation

def self extends abstrastFoo(self, ...) { ... }

Unless stated otherwise, all text on this page which is either unattributed or by Mark S. Miller is hereby placed in the public domain.

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