blob: 43e21001b9e782979165dbcb939442377912707b (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
# Mixfix
Mixfix functions allow arbitrary infix operations based on "substitution
holes" by using the `…` symbol in definitions. The symbols and terms
always need to be delimited by a space character, otherwise they get
interpreted as a [prefix](prefix.md).
Example:
``` bruijn
…+… add
# the "holes" get applied in normal order
:test ((+4) + (+3)) (add (+4) (+3))
```
You can define as many holes as you like. Make sure to place parenthesis
for applications inside substitution holes.
``` bruijn
{…<$>…|… [[[2 - 1 + 0]]]
# evaluated as (5 - 2) + 1 = 4
:test ({ (+5) <$> (+2) | (+1)) ((+4))
:test ({ ((+3) + (+2)) <$> (+2) | (+1)) ((+4))
```
You can use them as normal functions by writing the identifier
literally:
``` bruijn
:test (…+… (+4) (+3)) (add (+4) (+3))
```
## Associativity
If you write several mixfix operations without parenthesis, they will be
reduced in left-associative order. Just make sure that the longer mixfix
chain is not actually overwritten by *another* mixfix chain.
``` bruijn
:test ((+8) + (-4) ⋅ (-2)) ((-8))
…+…⋅… [[[2 + (1 ⋅ 0)]]]
:test ((+8) + (-4) ⋅ (-2)) ((+16))
```
## Allowed characters
Mixfix functions can use any characters of `!?*@:;+-_#$%^&<>/\|{}~=` as
well as mathematical unicode operators and arrows. Each part must be at
least 1 character long.
|
