Trains

Unlike in many other APLs, trains in TinyAPL are written using special syntax: ⦅, ⋄and ⦆. They are a sequence of arrays, functions, adverbs and conjunctions that combine to create functions or modifiers.

1-trains

The simplest train is the 1-train:

⦅x⦆is x⍨;
⦅F⦆is F;
u _⦅_A⦆is u _A;
u _⦅_C_⦆_ vis u _C_ v;

2-trains

⦅x⋄y⦆is x⍨
⦅x⋄G⦆is x∘G
⦅F⋄y⦆is F∘y
⦅F⋄G⦆is F⍤G
⦅x⋄_A⦆is x _A
⦅F⋄_A⦆is F _A
u _⦅_A⋄G⦆is (u _A)⍤G
u _⦅_A⋄_B⦆is (u _A) _B
u _⦅_A⋄_C_⦆is (u _A) _C_ u*should this be changed to Over-like (u _A) _C_ (v _A)?
u _⦅x⋄_C_⦆is x _C_ u
u _⦅F⋄_C_⦆is F _C_ u
u _⦅_C_⋄y⦆is u _C_ y
u _⦅_C_⋄G⦆is u _C_ G
u _⦅_C_⋄_A⦆_ vis (u _C_ v) _A
u _⦅_C_⋄_D_⦆_ vis (u _C_ v)⍤(u _D_ v)

3-trains

⦅x⋄y⋄z⦆is y⍨
⦅x⋄y⋄H⦆is y⍨
⦅F⋄y⋄x⦆is y⍨
⦅F⋄y⋄H⦆is y⍨
⦅F⋄G⋄H⦆is F«G»H
⦅x⋄G⋄H⦆is (x∘G)⍤H
⦅F⋄G⋄z⦆is (G∘z)⍤F
⦅x⋄G⋄z⦆is (x G z)⍨
⦅x⋄_C_⋄z⦆is x _C_ z
⦅x⋄_C_⋄H⦆is x _C_ H
⦅F⋄_C_⋄z⦆is F _C_ z
⦅F⋄_C_⋄H⦆is F _C_ H
u _⦅_A⋄G⋄H⦆is (u _A)«G»H
u _⦅_A⋄_B⋄_C⦆is ((u _A) _B) _C
u _⦅x⋄_C_⋄_A⦆is x _C_ (u _A)
u _⦅F⋄_C_⋄_A⦆is F _C_ (u _A)
u _⦅_A⋄_C_⋄z⦆is (u _A) _C_ z
u _⦅_A⋄_C_⋄H⦆is (u _A) _C_ H
u _⦅F⋄G⋄_C_⦆_ vis F«G»(u _C_ v)
u _⦅x⋄G⋄_C_⦆_ vis (x∘G)⍤(u _C_ v)
u _⦅_C_⋄G⋄H⦆_ vis (u _C_ v)«G»H
u _⦅_C_⋄G⋄_D_⦆_ vis (u _C_ v)«G»(u _D_ v)
u _⦅_A⋄_B⋄H⦆_ vis (u _A)«(v _B)»H
u _⦅_C_⋄_A⋄_B⦆_ vis ((u _C_ v) _A) _B
u _⦅x⋄_C_⋄_D_⦆_ vis x _C_ (u _D_ v)
u _⦅F⋄_C_⋄_D_⦆_ vis F _C_ (u _D_ v)
u _⦅_A⋄_C_⋄_B⦆_ vis (u _A) _C_ (v _B)
u _⦅_A⋄_C_⋄_D_⦆ vis (u _A) _C_ (u _D_ v)
u _⦅_C_⋄_D_⋄z⦆_ vis (u _C_ v) _D_ z
u _⦅_C_⋄_D_⋄H⦆_ vis (u _C_ v) _D_ H
u _⦅_C_⋄_D_⋄_A⦆_ vis (u _C_ v) _D_ (v _A)
u _⦅_C_⋄_D_⋄_E_⦆_ vis (u _C_ v) _D_ (u _E_ v)

Longer trains

Longer trains are parsed right-to-left, two tines at a time, creating 3-trains; the result of an evaluation becomes the rightmost tine of the next group. If only a tine is left it is used to create a 2-train. If the left tine of a 3-train is empty, it becomes a 2-train. This can be useful to force a chain of functions to be an Atop instead of a Fork.

Docs

Trains

1-trains

2-trains

3-trains

Longer trains