List comprehension

[raviqqe]

Problems

• Map and filter functions for lists are ones of operations most commonly used in functional programming.
• The language doesn't provide any primitive for those.
  • However, it also provides code consistency around iterative logic.

Why not reduce?

• Reduce operation is quite dependent on domain logic.
• New syntax for reduction might not actually give any benefit in terms of simplicity or conciseness.

Solution

• Provide a list comprehension syntax.
• The syntax currently proposed are borrowed from the ones of Python.
  • It needs more research around other languages.

Map

[foo(x) for x in xs]

Nested (flat) map

• Why does Python have a kind of inverted for order?

[foo(x) for x in xs for xs in xss]

Filter

[x for x in xs if x < 42]

[raviqqe]

Implemented in #640.