< Main

Disciple vs Haskell

These are some syntactic differences that tend to trip up Haskell programmers when they first start with Disciple.

• Disciple uses strict / call-by-value as the default evaluation order. This implies that bindings in let and where expressions must be written in dependency order. For example, you can write:

fun :: Int -> Int
fun x = x + z
 where  y = g x
        z = 3 + y

but not:

fun :: Int -> Int
fun x = x + z
 where  z = 3 + y
        y = g x

This doesn't work because the bindings for y and z are in the "wrong" order.

For let and where expressions, all the bindings are evaluated in-order, before moving to the body.

• We use (.) for projection instead of function composition. If you want to compose two functions then use ($)