Fix lambda precedence

[xsebek]

• give lambdas lower precedence (9) then application (10)
• closes Parameters to case are not formatted with parens #1468

Before (with #1459):

❯ cabal run swarm -O0 -- format <(echo '\\m. case m (\\x. x + 1) (\\y. y * 2)')
\m. case m \x. x + 1 \y. y * 2

After:

❯ cabal run swarm -O0 -- format <(echo '\\m. case m (\\x. x + 1) (\\y. y * 2)')
\m. case m (\x. x + 1) (\y. y * 2)

[xsebek]

@byorgey I assume this is overly pessimistic - in the example case, only the inner lambda requires parentheses.

However, the least amount of parentheses might be harder to read. 😄

[byorgey]

Hah, yes, in theory, a lambda at the very tail end of an expression does not need parentheses, but that would be annoying to read. I think this is fine.

[byorgey]

Hah, yes, in theory, a lambda at the very tail end of an expression does not need parentheses, but that would be annoying to read. I think this is fine.