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Oil Keywords

Related:

• Procs and Blocks
• Variables

Two Styles of Variable Declaration and Assignment

Legacy Style: readonly, local, name=val

They don't allow expressions on the right.

Oil's Style: const, var, setvar, setglobal, and setref

See the doc on variables for details.

Expressions Go on the Right

Just like with assignments.

= Pretty Prints an Expression

Useful interactively.

$ = 'foo'
(Str)   'foo'

$ = :| one two |
(StrArray)   ['one', 'two']

_ Ignores an Expression

Think of this:

_ f(x)

as a shortcut for:

_ = f(x)  # assign to "meh" variable

Other Kinds of Assignment

auto for Autovivification (future, not implemented)

auto count += 1

auto hist['key'] += 1

auto total += 3.5
auto hist['key'] += 4.6

Notes and Examples

Mutating Arrays

Use setvar:

Shell:

a=(one two three)
a[0]=zz

Oil:

var a = :| one two three |
setvar a[0] = 'zz'  # also acceptable

Mutating Associative Arrays

Shell:

declare -A A=(['name']=foo ['type']='dir')
A['type']=file

Oil:

var A = {name: 'foo', type: 'dir'}
setvar A['type'] = 'file'  # also acceptable

proc Disables Dynamic Scope

Recall that procs are the way to declare shell-like functions in Oil.

proc p {
  echo one
  echo two
}

p > file.txt

They mostly look like and work like shell functions, but they change scoping rules.