Hst hst

Dotted values in patterns

Dotted values can occur in a pattern, such as in the parameters to a named function:

f(a.b) = a + b

Based on some experimentation, it turns out that the left-hand side of a dotted pattern must match the first element of a dotted value. The right-hand side must match the “rest” of the dotted value. If the dotted value only contains two elements, then that means it must match the second element. If it contains more than two elements, then that means it must match a slightly smaller dotted value:

a.b matches 1.2 (a == 1, b == 2) a.b matches 1.2.3 (a == 1, b == 2.3) a.b.c matches 1.2.3 (a == 1, b == 2, c = 3) 1.b matches 1.2.3 (b == 2.3) a.3 DOES NOT MATCH 1.2.3 (a == 1, but 3 doesn't match 2.3)

Lighthouse: [#15 state:resolved] http://github.com/hst/hst/commit...