assignments.md

Assignment

Assignment expression assigns the right-side value to the left-side variable.

a := 2 * 3
a.p # 6

# right-side assignment
"hello" + "world" => b
b.p # helloworld

Why := (not =)?

Although = is shorter, it would conflict with strict chain.

# REJECTED SYNTAX
a = 1
# assignment of anonymous chain (a = (.b)) or strict chain property call (a=.b)?
a = .b

Why := is not an operator (method)?

If := were an operator, it would be a mutable method that updates environment. It can be abused to use environment as mutable object, which is not desirable for Pangaea concept. Instead, the idea "environment as mutable object" is encapsulated as iterators (Iterator).

Reassignment

You can also reassign values to variables already defined.

a := 2
a.p # 2
a := 3
a.p # 3

You can also use compound assignments. Note that this is reassignment, not mutable change.

a := 1
a.p # 1
a += 1
a.p # 2

Why is reassignment permitted?

Reassignment is permitted for compound assignment and shadowing. Also, reassignment is suitable for REPL.