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Mröw

Blocks

The Blocks type represents a Scratch script. It is a collection of Blocks, as the name suggests. Every script starts with a hat block, and then has a list of regular blocks.

Initiating a script

To initiate a script, you just call a function that returns one. These are most often of the pattern on_*.

src/my_project.gleam
sprite.sprite()
|> sprite.blocks(
  events.on_flag()
  |> ...,
)

Adding blocks to a script

Just having a standalone hat block isn’t particularly useful, so you an also add blocks onto a hat block. To do that, pipe the hat block into a block function. Block functions get in the current state of blocks and add their block to it:

src/my_project.gleam
sprite.sprite()
|> sprite.blocks(
  events.on_flag()
  |> looks.hide(),
)

Some blocks also take in operators as parameters.

Adding C-blocks to a script

When trying to use C blocks, you’ll notice that you can’t just put in the C blocks in as regular blocks, as that is ambiguous:

src/my_project.gleam
sprite.sprite()
|> sprite.blocks(
  events.on_flag()
  |> events.repeat(ops.int(5))
  |> motion.turn(ops.int(90)) // does the loop already end here?
  |> control.wait(ops.int(2)), // or does it end here?
)

Instead, a special function is used to group these blocks together. That function is blocks.c - which is used often enough that it warrants being imported standalone. blocks.c is treated as a normal block function - you can put other blocks before or after it.

src/my_project.gleam
import mroew/blocks.{c}


sprite.sprite()
|> sprite.blocks(
  events.on_flag()
  |> c(
    events.repeat(ops.int(5))
    |> motion.turn(ops.int(90))
    |> control.wait(ops.int(2)), // the loop ends here!
  ),
)

C blocks can take in operators as well.