There are two floating point types, Float32 and Float64, which correspond to the binary32 and binary64 types defined by IEEE.

A floating point literal is an optional + or - sign, followed by a sequence of numbers or underscores, followed by a dot, followed by numbers or underscores, followed by an optional exponent suffix, followed by an optional type suffix. If no suffix is present, the literal's type is Float64.

1.0      # Float64
1.0_f32  # Float32
1_f32    # Float32

1e10     # Float64
1.5e10   # Float64
1.5e-7   # Float64

+1.3     # Float64
-0.5     # Float64

The underscore _ before the suffix is optional.

Underscores can be used to make some numbers more readable:

1_000_000.111_111 # a lot more readable than 1000000.111111, yet functionally the same

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